CA2018719C - Token passing type slotted loop network system with means for enabling high speed access control and simple frame slot stripping - Google Patents
Token passing type slotted loop network system with means for enabling high speed access control and simple frame slot strippingInfo
- Publication number
- CA2018719C CA2018719C CA002018719A CA2018719A CA2018719C CA 2018719 C CA2018719 C CA 2018719C CA 002018719 A CA002018719 A CA 002018719A CA 2018719 A CA2018719 A CA 2018719A CA 2018719 C CA2018719 C CA 2018719C
- Authority
- CA
- Canada
- Prior art keywords
- token
- signal
- priority
- code
- separated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/42—Loop networks
- H04L12/427—Loop networks with decentralised control
- H04L12/433—Loop networks with decentralised control with asynchronous transmission, e.g. token ring, register insertion
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
- H04Q11/0478—Provisions for broadband connections
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5614—User Network Interface
- H04L2012/5615—Network termination, e.g. NT1, NT2, PBX
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5614—User Network Interface
- H04L2012/5616—Terminal equipment, e.g. codecs, synch.
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5638—Services, e.g. multimedia, GOS, QOS
- H04L2012/5646—Cell characteristics, e.g. loss, delay, jitter, sequence integrity
Abstract
Abstract of the Disclosure:
In a token passing slotted loop network comprising a master station and a plurality of slave stations, a plurality of slots circulating through the loop and each of the slots having a fixed length and comprising a header portion and a data carrier portion, a particular one of the stations having the token transmitting its own data signal by use of one or more of the slots, the particular station transmits an end mark in the header of a particular one of the slots at an end of transmission of the own data signal and strips incoming slots from a start of the transmission of the own data signal until reception of the end mark circulated through the loop. The particular station frees the token by inserting the token in the header of the particular slot. The token can be inserted in the header of one of the slots after completion of the transmission. Each of the slave stations writes into a priority request section in the header of each slot a particular priority request representative of a priority level of the own data signal when the own data signal occurs thereat. The master station writes the highest one of the priority request into a priority section in the header of each-slot. Each slave station detects the priority in the priority section and starts to acquire the token when the detected priority is lower than the particular priority request.
In a token passing slotted loop network comprising a master station and a plurality of slave stations, a plurality of slots circulating through the loop and each of the slots having a fixed length and comprising a header portion and a data carrier portion, a particular one of the stations having the token transmitting its own data signal by use of one or more of the slots, the particular station transmits an end mark in the header of a particular one of the slots at an end of transmission of the own data signal and strips incoming slots from a start of the transmission of the own data signal until reception of the end mark circulated through the loop. The particular station frees the token by inserting the token in the header of the particular slot. The token can be inserted in the header of one of the slots after completion of the transmission. Each of the slave stations writes into a priority request section in the header of each slot a particular priority request representative of a priority level of the own data signal when the own data signal occurs thereat. The master station writes the highest one of the priority request into a priority section in the header of each-slot. Each slave station detects the priority in the priority section and starts to acquire the token when the detected priority is lower than the particular priority request.
Description
201%7~9 A TOKEN PASSING TYPE SLOTTED LOOP NETWORK SYSTEM
WITH MEANS FOR ENA~LING HIGH SPEED ACCLSS
CONTROL AND SIMPLE F~AME SLOT STRIPPING
ound of the Invention:
1. Field of the Invention The present invention relates to a token passing type slotted loop network system wherein a plurality of 5 node stations are connected by transmission lines to form a data transmission ring or loop, each station sending out its own data signal in a slot or slots on the loop after capturlng the token, and in particular, to frame stripping, access control and priority control 10 in such a token passing type slotted loop network system.
WITH MEANS FOR ENA~LING HIGH SPEED ACCLSS
CONTROL AND SIMPLE F~AME SLOT STRIPPING
ound of the Invention:
1. Field of the Invention The present invention relates to a token passing type slotted loop network system wherein a plurality of 5 node stations are connected by transmission lines to form a data transmission ring or loop, each station sending out its own data signal in a slot or slots on the loop after capturlng the token, and in particular, to frame stripping, access control and priority control 10 in such a token passing type slotted loop network system.
2. Description of the Prior Art In such a slotted loop network system, a particular one of the node stations transmits its own 15 data signal by use of one or more of the plurality of slots. However, the particular node station is responsible for stripping from the loop the slots which '~ . .
2018~19 it used for transmitting the own data signal. The stripping is performed by use of address data in the own data signal or by node address data attached into the used slot. However, it takes a long time to detect the 5 address data so that stripping is delayed.
As the data signal to be transmitted, there two types, one being a slmpl~ pa~ket signal having a 90urce address and a destination, the other being an ATM
(Asynchronous Transfer Mode) type having a different 10 address data signal which is called a VCI (Virtual Channel Identifier) which is different from those source and destination address type. In the loop network system handling those different type data signals, the stripping is further complex.
In a conventional token passing ring (IEEE802.5), a token frame is circulated through the loop. When a particular one of node stations acquires ~he token frame, the particular node station has a transmission right to transmit the own data signal 20 together with the token to the loop. However, when the transmission of the own data signal is ended, the token cannot be freed until the final data frame returns to the particular node station. Therefore, the process for acquiring the token frame by another node sation is 25 comparatively complex and takes a long time.
In order to enable a high speed access control, a method is known in the prior art wherein the particular node station frees the token just after 20~71~
comple~ion of the transmissiGn of the own data signal.
The FDDI (Fiber Distributed Data Interface) uses such a method. However, it is impossible in the method to perform the priority control of transmission requests 5 originated from several node stations.
Summary of the Invention~
Accordingly, it is an ob~ect of the present invention to provide a token passlng ~ype slotted loop network system which enables to readily perform the slot 10 stripping without any address data.
It is another object of the present invention to provide a token passing type slotted loop network system which enables to perform the access control with a reduced time.
It is another object of the present invention to provide the above described token passing type slotted loop network system which the priority control is also possil:~le .
According to the present invention, a token 20 passing type slotted loop network system is obtained which comprises a master node station and a plurality of slave node stations connected to each other to form a data transmission loop, a plurality of slots being circulated on the loop for transmitting a data signal 25 from a particular one of the node stations having the token. Each of the slots having a fixed length and comprises: a header portion comprising an end/non-end code section for carrying the end/non-end code, the end 20~8~19 code and the non-end code representing an end and a non-end of transmission of the data signal; and a data carrier portion for carrying the data signal. Each of the master and slave node stations comprises:
5 multiplexing means for multiplexing input signals applied thereto to produce a multiplexed signal, the multiplexed signal being delivered therefrom to the loop; transmission bu~fer mQans for hol~ing tho data signal to be transmitted to the loop as a buffered data 10 signal as one of the slots; demultiplexing means for demultiplexing each of the slots sequentially incoming thereto as an incoming slot signal to produce the end/non-end code section and a remaining portion as a separated end/non-end signal and a separated data lS signal; selecting means coupled to the demultiplexing means and the transmission buffer means for selecting the separated data signal at a repeating mode and the buffered data signal at a tran9mi9sion mode as.a selected signal, the sele~ted signal being delivered to 20 the multiplexing means as one of the input signal;
end-mark processing means coupled to the demultiplexing means for repeating the separated end/non-end signal to the multiplexing means as another one of the input means at a repeating condition, the end-mark processing means 25 producing the non-end code signal and the end code signal to deliver the non-end code signal and the end code signal to the multiplexing means as another input signal at a non-end condition and an end condition, 20187~9 s respectively; and control means coupled to the demultiplexing means, the transmission buffer means, the selecting means and the end-mark processing means for controlling the end-mark processing means and the S selecting means.
In the particular node station, the control means makes the end-mark processing means and the selecting means be in the non-end conditlon and in the transmission mode, respectively. The control means 10 monitors the transmission buffer means and makes the end-mark processing means be in the end condition to produce the end code signal at an end of transmission of the buffered data signal. The control means makes the end-mark processing means and the selecting means be in 15 the repeating condition and in the repeating mode, respectively, when the control means detects that the demultiplexed end/non-end signal is the end code signal.
In each of the node stations other than the partlcular node station, the control means màkes tha end-mark 20 processing means and the selecting means be in the repeating condition and in the repeating mode, respectively.
According to another aspect of the present invention, the header portion further comprises a 25 token/non-token code section for carrying one of a token code representing the token and a non-token code. The demultiplexing means separates the token/non-token code section from the incoming slot signal to produce a 20187i9 separated token/non-token signal. Each of the master and the slave node stations further comprises token processing means coupled to the demultiplexing means for repeating the separated token/non-token signal to the 5 multiplexing means as another one of the input signals at a repeating condition. The token processing means produces the non-token code signal and the token code signal to deliver the non-token code signal and the token code signal at a non-token condition and~a token 10 condition, respectively, to the multiplexing means as another input signal, the control means controlling the token/non-token processing means.
The control means makes the token processing means be in the non-token condition in order to acquire lS the token when detecting that the transmission buffer means holds the buffered data signal, and the control mean~ acquires the token when detecting that the separated token/non-token ~ignal is the token code signal. Thus, the control means, as the control means 20 in the particular node station, makes the end-mark processing means and the selecting means be in the non-end condition and the transmission mode.
In the particular node station, the control means makes the token processing means be in the token 25 condition so as to free the token at the end of transmission of the buffered data signal and then makes the token processing means into the repeating condition.
20~8719 When the data signal has a priority of one of different priority levels from a minimum level and a maximum level, the header portion further comprises a priority request section for carrying a priority request S representing a priority level requested at each of the slave node stations, and a priority section for carrying the highest priority level in the priorlty request ae an indication prlority level. The demultlplexing means separates the priority request section from the incoming 10 slot signal as a separated priority request. The master node station further comprises priority control means coupled to the demultiplexing means responsive to the separated priority request for detecting the highest priority level in the separated priority request as a 15 detected priority level to set the detected priority level in the priority section as the indication priority level. The priority control means sets a non-request code in the priority requ~st s~ction.
The control ~eans in each of the slave node 20 stations monitors the transmission buffer means to detect a particular one of the priority levels requested by the buffered data signal in the transmission buffer means as a particular priority request. Each of the slave node stations further comprises priority register 25 means coupled to the control means for holding the particular priority request; and priority request processing means coupled to the demultiplexing means and the priority register means for producing a specific . .
' 2~8~
priority request from the particular priority request and the separated priority request to deliver the specific priority request as another one of the input signals to the multiplexing means.
S In each of the slave node station, the demultiplexing means demultiplexes the priority section in the incoming slot signal as a separated priority signal. The separated priority signal is delivèred as another of the input signals to the multiplexing means.
10 The control means responsive to the separated priority signal compares the indication priority level of the separated priority signal with the particular priority request level and make~ the token processing means be in the non-token condition when the particular priority lS request level is equal to or higher than the indication priority level of the ~eparated priority signal.
When the priority is divided into N ~N being an integer) levels from the minimum lavel to tha maximum level, the priority request is represented by a binary 20 code of N digits with "1" in different digits representing different priority levels so that "1" of the highest and the lowest digits represents the maximum and the minimum levels. The priority request processing means comprises means for writing "1" into a particular 25 digit in the separated priority request signal corresponding to the particular priority request.
2~187~9 Brief Description of the drawings:
Fig. 1 is a diagram view of a token passing type slotted loop network system to which the present invention is applicable;
S Fig. 2 is a view illustrating a slot format used in an embodiment of the present invention;
Flg. 3 i~ a bloek dlag~m o~ a ma~ter node gtation in the loop network in Fig. 1 according to an embodiment of the present invention;
Fig. 4 is a block diagram of a slave node station in the loop network in Fig. 1 according to the embodiment of the present invention;
Fig. 5 is a flow chart illustrative of operation of priority control in the master node station in 15 Fig. 4;
Fig. 6 i9 a flow chart illustrative of operation of priority request processor in each node station in Fig. 4;
Fig. 7 is a flow chart illustrative of operation 20 for acquiring a token by each node station in Figs. 3 and 4;
Fig. 8 is a flow chart illustrative of operation for transmitting data in a node station in Figs. 3 and 4;
Fig. 9 is a diagram view illustrating a data frame in a node station and a slot sent out from the node station;
2 0~8~1~
Fig. 10 is a diagram view illustrating another data frame in a node station and slots sent out from the node station; and Fig. 11 is a diagram view illustrating slot 5 transmitting operation in adjacent node stations.
Description of Preferred Embodiments~
Referring to Fig. 1, a token passing type slotted loop network system oomprises a plurality of node sta~ions ~our stations 11 through 14 are 10 exemplarily shown) connected through transmission lines to form a ring or loop 15, as well known in the prior art. The first (#l) node station 11 is a master station and the other second through fourth (#2 - #4) node stationq 12-14 are slave node stations.
A plurality of slots circulates on the loop 15 under control by the master node station 11 and repetition at each of the slave node stations 12-14.
Referring to Fig. 2, each slot has a format of a fixed length which comprises a header por~ion 1~ o 20 eight ~8) bytes an,d a user's data carrier portion 17 of forty-eight (48) bytes. The header portion 16 comprises a logical network identification (ID) field 18 of one byte, an access control field (ACF) 19 of two (2) bytes, a VCI field 20 of four (4) bytes and a header error 25 correction field 21 of one byte.
The logical network ID portion 18 is for carrying an identifier representative of a logical network type used in the network system.
The ACF field 19 is for carrying access control data and comprises a slot type identifier (SL TYPE) section 22, a priority request section 23, a busy/idle (BUSY) section 24, an end mark (END) section 25, a 5 chaining code (CHAIN) section 26, a master/slave (MASTER) section 27, a token/non-token (TOKEN) section 28, and a priority section 29.
The slot type identi~ier sea~ion 22 is for carrying a code representative of a type of the user's 10 data signal which is ~ransmitted by the same slot.
There are two types for the user's data signal, that is, a simple packet type and an ATM type as described in the preamble. The slot type identifier is a one-bit code and ~0" and "1" of the code represent, for example, the 15 simple packet type and the ATM type, respectiveiy.
The priority request section 23 is for carrying a priority request signal (PRI-REQ) of a request code representing priority levels requested in node stations.
The request code has a four-bit length in the present 20 embodiment. The priority is divided into four levels, that is, the minimum level "I" through the maximum level "IV" which are corresponding to "1" of the lowest digit through the highest digit of the four-bit request code, respectively. Therefore, the four priority levels "I' 25 to "IV" are represented by "0001" to "1000" which are called first through fourth requested level code Rl to R4. The requested level codes Rl to R4 are collectively called the request code R.
2018~g The busy/idle section 24 is for carrying a one bit code signal representing whether the same slot is busy or idle. The code is "l" when the slot is busy but is "0" when the slot is idle.
The end mark section 25 is for carrying an end/non-end signal of one bit representing whether or not the same slot i9 the last one for transmitting the current user'~ data signal . When the end/non-~nd signal is UlU, the signal means that the same slot is the last lO one and is called an end mark signal El. When the end/non-end signal is "0", the signal means that the same slot is not the last one and is called a non-end mark signal E0.
The chaining code section 26 is for carrying a lS chaining code signal of two-bit length which identifies a section of the current user's data signal transmitting the same slot. When the current user's data signal is wholly transmitted in the same tlme slot, the chaining code is "00" and is called a single code signal C0. The 20 current user's data signal is the ATM type signal, the chaining code signal is the single code signal C0. When the current user's data signal is a comparatively large length so that it should be divided into a plurality of data sections which are transmitted by a plurality of 25 subsequent slots, a start code "lO" signal Cl and a last code "01" signal C3 are given in the individual chaining code sections of the first and the last slots for transmitting the first and the last data sections, 13 201871~
respectively, and an intermediate code "11" signal C2 is given in the chaining code section or sections of intermediate slot or slots for transmitting intermediate data section or sections.
The master/slave section 27 is for carrying a code of one bit representing which the same slot is used by, the master or the slave node station, When the same slot is used by the master node sta~ion, the code is "1"
and is called a master code Ml. While, the code i9 ~0~
10 and i9 called a slave code M0 when the same slot is used by any one of the slave node stations.
The token/non-token section 28 is for carrying a token/non-token signal of one bit. The token signal Tl has a token code ~1", while the non-token signal T0 has 15 a non-token code "0". In the known manner, the token signal Tl is in only one of the slots on the loop when no node station acquires the transmission right, while it is not in an~ one of the slots on the loop when one of the node stations has the transmission right.
20 However, it should be noted that the token signal Tl is inserted in the header portion 16 in one of the slots.
The priority section 29 is for carrying a priority signal (PRI) as an indication priority level representative of the highest priority level in the 25 priority request section 23 written during a previous complete circulation of the same slot through the loop.
Since the priority is divided into four levels "I"
through "IV" as described above, the priority levels "I"
2 0~871~
through "IV" are represented by binary codes "00"
through "11". Those binary codes are referred to as priority level codes PO through P3, respectively, and are collectively called a priority code P.
S Referring to Fig. 3, the master node station 11 comprises a demultiplexer 31 for demultiplexing each one of a sequence of 410ts incoming through the loop 15 to produce the priority signal (PRI), the priority request slgnal 'PRI-REQ), the token/non-token signal (TOKEN), 10 the end/non-end signal (END MARK), and the remaining portion of the slots as a data portion signal.
The master node station 11 further comprises a reception buffer 32, a transmission buffer 33, a buffer controller 34, an access controller 35, a priority 15 controller 36, a register 37, a token processor 38, an end-mark processor 39, a data selector 40, and a multiplexer 41.
The reception bufer 32 temporarily holds the incoming slot signal and sends out the user' 9 data 20 portion in the incoming slot signal to a terminal (not shown) accommodated in the master node station 11 when the user's data signal in the user's data carrier portion of the incoming slot is destined to the terminal under control of the buffer controller 34.
The transmission buffer 33 temporarily stores a data signal as a buffered data signal from the terminal accommodated in the master node station 11. The buffer controller 34 monitors the transmission buffer 33 to 2018~19 detect the buffered data signal therein to be transmitted to the loop and delivers information for access control to the access controller 35.
The access controller 35 controls the buffer 5 controller 34, the priority controller 36, the token processor 38, the end-mark processor 39, and the data selector 40 in the manner as will later be described.
The multiplexer 41 receives the priority signal ~PRI) from the register 37, the prlority request signal 10 (PRI-REQ) from the priority controller 36, the token signal from the token processor 38, the end/non-end signal (END MARK) from the end-mark processor 39, and the data signal from the data selector 40, and produces a new slot signal having the format shown in Fig. 2 lS which i9 delivered to the loop lS.
When the master node station does not have the token, the token processor 38, the end-mark processor 39 and the data 9elector 40 transfer the token/non-token signal ~, the end/non-end signal E and the other data 20 portion signal, respectively, from the demultiplexer 31 to the multiplexer 41.
The master node station 11 is provided with a delay controller 42 as a stage prior to the demultiplexer 31. The delay controller 42 is for 25 controlling a loop delay of each slot to be equal to an integer time of the slot length.
Referring to Fig. 4, each of the slave node stations 12-14 is similar to the master node station 11 16 :20~$7~
and the similar portions are represented by the same reference numerals in Fig. 3. That is, the slave node station comprises the demultiplexer 31, the reception buffer 32, the transmission buffer 33, the buffer 5 controller 34, an access controller 35', the token processor 38, the end-mark processor 39, the data selector 40, and the multiplexer 41. The slave node ~tation further comprlses a priority register 42 and a priority request processor 43 in place of the priority 10 controller 36 and the register 37 in the master node station 11.
The access controller 35' in the slave node station is similar to the access controller 35 in the master node station but different in that the former 15 controls the priority register 42 and the priority request processor 43 in place of the priority controller 36 and the register 37 in the master node station 11.
Thereafter, the acCess controller in each o the slave node station is represented by not 35 but 35'.
When each of the slave node station has no data signal to be transmitted, the priority request processor 43, the token processor 38, the end-mark processor 39 and the data selector 40 are at a repeating condition and transfer the priority request signal, the 25 token/non-token signal, the end/non-end signal and the other data signal from the demultiplexer 31 to the multiplexer 41. Further, the priority signal is directly transferred from the demultiplexer 31 to the 201871;9 multiplexer 41. Therefore, the each of the slave node station repeat the incoming slot signal.
Returning to Fig. 3 and additionally referring to Fig. 5, description is made as to operation of the 5 priority controller 36 and the register 37 in the master node ~tation 11. On start of the ~ystem, the priority controller 3~ produces a non-request code RO ~0000) as the priority request signal (PRI-REQ), as shown at a step 51 in Fig. 5. Then, the multiplexer 41 multiplexes 10 the priority request signal (PRI-REQ) with other signals to form a slot signal which is delivered to the ioop 15.
The slot circulates the loop 15 and i5 received at the demultiplexer 31 in the master node station 11 as a returned slot signal. During the circulation, each of 15 the slave node stations 12-14 writes into the priority request section of the slot the request code R generated ln each slave node station. ~he demultiplexar 31 ln the mastQr node station 11 separates the priority request section from the returned slot signal to produce the 20 priority request signal (PRI-REQ) which is received at the priority controller 36 as shown at a step 52. Then, the priority controller 36 generates a priority code P
as the indication priority corresponding to the highest level of the request code R in the priority request 25 signal (PRI-REQ) and writes the priority code P into the register 37. The register 37 delivers the priority code P as the priority signal (PRI) to the multiplexer 41, as shown at a step 53. The priority controller 36 again 18 2~1-8~
produces the non-request code R0 which is also delivered to the multiplexer 41. Then, a new slot is formed and delivered from the multiplexer 41 to the loop. The priority signal and the priority request signal are set 5 in the header of the new slot. Thereafter, similar operation is repeated.
Referring to Figs. 4 and 6, description ls now made as to operation of the priority request processor 43 under control of the priority register 42 and the 10 access controller 35' in each of the slave node stations 12-14.
When the transmission buffer 33 holds the user's data signal to be transmitted to the loop, the access controller 35' detects a priority level of the user's 15 data signal through the buffer controller 34. Then, the access controller 35' produces the request code R
corresponding to the priority level and delivers the request code R to the priority register 42. The priority register 42 supplies the request code R to the 20 priority request processor 43.
The slot delivered to the loop from the master node station 11 is received at the demultiplexer 31 in the slave node station. The demultiplexer 31 separates the priority request section in the slot and produces 25 the priority request signal (PRI-REQ) which is applied to the priority request processor 43 at a step 54 in Fig. 6.
2~71.~
The priority request processor 43 comprises four OR gates 431 through 434 which are corresponding to the highest bit through the lowest bit of the request code R. The priority request signal (PRI-REQ) of four bits 5 are applied to individual input terminals of OR gates 431-434 while four bits request code R are applied to lndivldual second input terminals o~ OR gates 431-434.
Therefore, the request code R is combined with the priority request signal (PRI-REQ) at a step SS to 10 produce a fresh one of the priority request signal IPRI-REQ).
In the node station, when the request code R is, for example, R1 (0001), the R1 is combined with the non-request code RO (0000) of the received priority lS re~ue~t signal (PRI-REQ), a code of the priority request signal is changed into a combined priority request code (RO~R1) or (0001).
~he combined or changed priority request -4ignal (PRI-REQ) is supplied to the multiplexer 41 at a step 56 20 and is multiplexed with the other repeated signals to rep.roduce the slot which is delivered to the loop.
At the downstream slave node station, when the request code R is, for example, R3 (0100), the code of the combined priority request (RO+Rl) received thereat 25 is combined with R3 and is changed into another modified priority request (R0+Rl+R3) or (0101) in the similar manner as described above.
~ ....
Thereafter, the node station monitors the priority signal (PRI) in the slot received thereat.
Referring to Fig. 7, the access controller 35' monitors the priority signal (PRI) in the incoming slot 5 signal stored in the reception buffer 32 through the buffer controller 34 at a step 57. The priority level ind~cated by the monitored prio~ity signal ~PRI) is compared with thè own priority level requested by the subscriber's data signal stored in the transmission 10 buffer 33 at a step 58. When the former is lower than the latter, the access controller 35' makes the token processor 38 acquire the token code Tl at a step 59.
The token processor 38 comprises an OR gate 381 and an AND gate 382. The token/non-token signal T
15 separated from the incoming slot at the demultiplexer 31 is applied to a Pirst input terminal of the OR gate 381.
An output of the OR gate 381 is coupled to a first input terminal of the AND gate 382. Second input terminals of the OR gate 381 and the AND gate 382 are coupled to the 20 access controller 35'. The token/non-token signal T is also applied to the access controller 35'. Normally, the access controller 35' supplies an OR gate control signal with a level "0" and an AND gate control signal with a level "1" to the second input terminals of the OR
25 gate 381 and the AND gate 382, respectively. Therefore, the token processor 38 is set in a repeating condition and repeats the token/non-token signal from said demultiplexer 31.
21 ~018~
At step 59, the access controller 35' changes the AND gate control signal from level "1" to level "0"
to set the token processor 38 in a non-token condition.
Accordingly, the AND gate 382 produces the non-token S code signal T0 of "0" level as the token/non-token slgnal T. The non-token code signal T0 is carried in the token/non-token section (~8 in Fig. 2) of tlle slot delivered from the multiplexer 41, whether the OR gate 381 produces "1" level signal or "0" level signal.
Thereafter, when the access controller 35' detects the token code Tl in the token/non-token signal T applied from the demultiplexer 31 at a step 60 in Fig.
8, the access controller 35' delivers a switch signal S
to the data selector 40 so as to connect the 15 transmission buffer 33 to the multiplexer 41 and a grant signal to the buffer controller 34 so as to start transmlssion of the subscriber's data signal stored in the transmission buffer 33 at step 61 in Fig. 8.
The user's data signal in the transmission 20 buffer 33 is transmitted by a single slot or a plurality of subsequent slots as described above.
The access controller 35' monitors the transmission buffer 33 through the buffer controller 34 to detect whether or not a plurality of slots are 25 required for transmission of the user's data signal at a step of 62.
When a plurality of slots are required, the transmission buffer 33 holds the user's data signal .
together with the start code Cl, the last code C3 and the intermittent code C2 which are carried in the chaining code section in individual slots delivered from the multiplexer 41.
Thereafter, the access controller 35' monitors through the buffer controller 34 at a step 63 whether or not the final slot iq started from transmission of the buffered data in the transmissi~n buer 33. When the flnal slot i9 started, the access controller 35' drives 10 the end mark processor 39 to produce the end mark El at a step 64.
The end mark processor 39 comprises an AND gate 391 and an OR gate 392. The AND gate 391 has a first input terminal connected to the demultiplexer 31 for 15 receiving the end/non-end signal E separated from the incoming slot signal by the demultiplexer 31. The AND
gate 391 has an output terminal which i9 connected to a first input terminal of the OR gate 392. Second input terminals of the AND gate 391 and the OR gate 392 are 20 connected to the access controller 35' for receiving control signals therefrom. Normally, the access controller 35' supplies an AND gate control signal with a level "1" and an OR gate control signal with a level "0" to the second input terminals of the AND gate 391 25 and the OR gate 392, respectively. Therefore, the end-mark processor 39 is maintained at a repeating condition and the end/non-end signal E from the demultiplexer 31 is repeated. The access controller 35' 2~,8~
is also supplied with the end/non-end signal E from the demultiplexer 31.
At step 64, the access controller 35' changes the OR gate control signal from "0" level to "1" level 5 to make the end-mark processor be in an end condition.
Therefore, the OR gate 392 produces the end mark signal El of "1" le~el whether the output of the AND gate 391 is level "0" or "1" signal.
When the user's data signal can be transmitted 10 by a single slot, or the user's data signal is the ATM
signal, the transmission buffer 33 holds the user's data signal together with the single code C0 which is carried in the chaining code section in the slot delivered from the multiplexer 41. Then, the end mark El is also 15 produced at step 64.
Thereafter, the access controller 35' çontrols the token processor 38 lnto a token condition by changing the AND gate aontrol signal from "0" level to "1" level and by supplying the OR gate control signal of 20 a level "1" signal to the OR gate 381. Accordingly, the token code signal Tl of ~1" is produced and delivered to the multiplexer 41 at step 65. Thereafter, the access controller 35' makes the token processor be in the repeating condition.
The end mark code signal El and the token code signal Tl are carried in the end/non-end signal section 25 and the token/non-token section 28 in the header 20~871~
portion 16 of the slot delivered from the multiplexer 41.
Then, the transmission of the user's data signal is completed.
Fig. 9 illustrates transmission of an ATM packet signal by use of a single slot. The ATM signal 70 has a frame which comprises a label section comprising VCI
tvirtual cirauit indiaat~r) and a data section comprising an information field INFO and a frame check 10 sequence FCS. The slot for transmitting the ATM packet signal has the header portion 16 including the end mark signal El, the single code signal CO, the token code signal T1 and the VCI, and the data portion carrying the INFO and the FCS. The header of the next subsequent 15 slot is shown in the figure and includes the non-end mark signal EO, the single code CO and the non-token signal TO.
Fig. 10 illustrates transmission o a simple packet signal 71 as the user's data signal by use of 20 three slots.
The signal 71 is divided into three blocks I, II
and III which are carried in individual data carrier portions 17 in the three slots. As shown in the figure, the non-end signal EO, the non-token signal TO and the 25 start code Cl are carried in the header 16 ln the first slot. The non-end signal EO, the non-token signal TO
and the intermediate signal C2 are carried in the header in the second slot. The header of the third or final 201871~
slot has the end mark signal El, the final code signal C3 and the token signal Tl.
The header of tha next subsequent slot has the non-end mark signal E0, the single code C0 and the 5 non-token signal T0 like the slot shown in Fig. 9.
After the final slot is sent out from the multiplexer 41, the access controller 35' of the ~ame node 8tation detects the end mark signal El through the demultiplexer 31 at a step 66 in Fig. 8. Then, the 10 access controller 35' delivers an idler signal to the data selector 40 so as to restore the data selector 40.
Accordingly, the data selector 40 again couples the demultiplexer 31 to the multiplexer 41 90 that the data portion is repeated from the demultiplexer 31 .tb the lS multiplexer 41.
During a time period from step 61 to step 67 when the data selector 40 is switched onto the transmission buffer 33, incoming slot~ to the ~ame node ~tation ara stripped.
Furthermore, since the token signal Tl is inserted in the final slot for transmission of the user's data signal at step 65, the next downstream node station can acquire the token signal Tl just after the next upstream node station aborts the transmission right 25 by sending out the token signal Tl.
In the example of Fig. 10, the transmission buffer 33 holds a data signal and transfers the data signal by use of three slots. However, when the ~ ~18~1~
transmission buffer 33 holds several data signals as the buffered data signal and continuously transfers those several data signals, the last code signal C3 is carried by an individual last one of slots for transferring each 5 of the several data signals. However, the end mark signal El and the token signal Tl are not carried in all of the individual last slot and are only carried in the final one of ~lots for transerring the entire of the several data signals.
In the described embodiment, the token signal Tl is set in the final slot for transmission of the buffered data signal. However, the non-token signal T0 can be maintained in the final slot and the token signal Tl is freed in the next subsequent slot after the final lS slot. The case is shown by representations of (T0) and (Tl) in Figs, 9 and 10.
Referring to Fig. 11, description is made as to an exemplary case where ~2 node station 12 sends out three slots 121-123 thereafter #3 node station 13 sends 20 out four slots 131-134. At (b) in Fig. 11, the node station 12 delivers the three slots 121-123 to the loop.
The slots 121-123 are received by the node station 13 at (c). Then, the node station 13 can capture the token signal Tl. Therefore, the node station 13 repeats the 25 slots 121-123 and transmits the slots 131-134 at td).
The slots 121-123 and 131-134 are received by the node station 12 at (a). The node station 12 is set in a slot stripping condition during a time duration Dl from the 20187~
transmission start of slots 121-123 at (b) to the reception completion of the slots 121-123 at (a).
Thereafter, the node station repeats the slots 131-134 to the node station 13 at (b). Then, the node 5 station 13 receives the slots 131-134. The node station 13 is set in a slot stripping condition during a time duration D2 from the transmission 8tart of slots 131-134 at ~d) to the reception complation o the slot~ 131-134 at (c).
Therefore, slot stripping can readily be performed by use of the end mark signal without use of any address information.
2018~19 it used for transmitting the own data signal. The stripping is performed by use of address data in the own data signal or by node address data attached into the used slot. However, it takes a long time to detect the 5 address data so that stripping is delayed.
As the data signal to be transmitted, there two types, one being a slmpl~ pa~ket signal having a 90urce address and a destination, the other being an ATM
(Asynchronous Transfer Mode) type having a different 10 address data signal which is called a VCI (Virtual Channel Identifier) which is different from those source and destination address type. In the loop network system handling those different type data signals, the stripping is further complex.
In a conventional token passing ring (IEEE802.5), a token frame is circulated through the loop. When a particular one of node stations acquires ~he token frame, the particular node station has a transmission right to transmit the own data signal 20 together with the token to the loop. However, when the transmission of the own data signal is ended, the token cannot be freed until the final data frame returns to the particular node station. Therefore, the process for acquiring the token frame by another node sation is 25 comparatively complex and takes a long time.
In order to enable a high speed access control, a method is known in the prior art wherein the particular node station frees the token just after 20~71~
comple~ion of the transmissiGn of the own data signal.
The FDDI (Fiber Distributed Data Interface) uses such a method. However, it is impossible in the method to perform the priority control of transmission requests 5 originated from several node stations.
Summary of the Invention~
Accordingly, it is an ob~ect of the present invention to provide a token passlng ~ype slotted loop network system which enables to readily perform the slot 10 stripping without any address data.
It is another object of the present invention to provide a token passing type slotted loop network system which enables to perform the access control with a reduced time.
It is another object of the present invention to provide the above described token passing type slotted loop network system which the priority control is also possil:~le .
According to the present invention, a token 20 passing type slotted loop network system is obtained which comprises a master node station and a plurality of slave node stations connected to each other to form a data transmission loop, a plurality of slots being circulated on the loop for transmitting a data signal 25 from a particular one of the node stations having the token. Each of the slots having a fixed length and comprises: a header portion comprising an end/non-end code section for carrying the end/non-end code, the end 20~8~19 code and the non-end code representing an end and a non-end of transmission of the data signal; and a data carrier portion for carrying the data signal. Each of the master and slave node stations comprises:
5 multiplexing means for multiplexing input signals applied thereto to produce a multiplexed signal, the multiplexed signal being delivered therefrom to the loop; transmission bu~fer mQans for hol~ing tho data signal to be transmitted to the loop as a buffered data 10 signal as one of the slots; demultiplexing means for demultiplexing each of the slots sequentially incoming thereto as an incoming slot signal to produce the end/non-end code section and a remaining portion as a separated end/non-end signal and a separated data lS signal; selecting means coupled to the demultiplexing means and the transmission buffer means for selecting the separated data signal at a repeating mode and the buffered data signal at a tran9mi9sion mode as.a selected signal, the sele~ted signal being delivered to 20 the multiplexing means as one of the input signal;
end-mark processing means coupled to the demultiplexing means for repeating the separated end/non-end signal to the multiplexing means as another one of the input means at a repeating condition, the end-mark processing means 25 producing the non-end code signal and the end code signal to deliver the non-end code signal and the end code signal to the multiplexing means as another input signal at a non-end condition and an end condition, 20187~9 s respectively; and control means coupled to the demultiplexing means, the transmission buffer means, the selecting means and the end-mark processing means for controlling the end-mark processing means and the S selecting means.
In the particular node station, the control means makes the end-mark processing means and the selecting means be in the non-end conditlon and in the transmission mode, respectively. The control means 10 monitors the transmission buffer means and makes the end-mark processing means be in the end condition to produce the end code signal at an end of transmission of the buffered data signal. The control means makes the end-mark processing means and the selecting means be in 15 the repeating condition and in the repeating mode, respectively, when the control means detects that the demultiplexed end/non-end signal is the end code signal.
In each of the node stations other than the partlcular node station, the control means màkes tha end-mark 20 processing means and the selecting means be in the repeating condition and in the repeating mode, respectively.
According to another aspect of the present invention, the header portion further comprises a 25 token/non-token code section for carrying one of a token code representing the token and a non-token code. The demultiplexing means separates the token/non-token code section from the incoming slot signal to produce a 20187i9 separated token/non-token signal. Each of the master and the slave node stations further comprises token processing means coupled to the demultiplexing means for repeating the separated token/non-token signal to the 5 multiplexing means as another one of the input signals at a repeating condition. The token processing means produces the non-token code signal and the token code signal to deliver the non-token code signal and the token code signal at a non-token condition and~a token 10 condition, respectively, to the multiplexing means as another input signal, the control means controlling the token/non-token processing means.
The control means makes the token processing means be in the non-token condition in order to acquire lS the token when detecting that the transmission buffer means holds the buffered data signal, and the control mean~ acquires the token when detecting that the separated token/non-token ~ignal is the token code signal. Thus, the control means, as the control means 20 in the particular node station, makes the end-mark processing means and the selecting means be in the non-end condition and the transmission mode.
In the particular node station, the control means makes the token processing means be in the token 25 condition so as to free the token at the end of transmission of the buffered data signal and then makes the token processing means into the repeating condition.
20~8719 When the data signal has a priority of one of different priority levels from a minimum level and a maximum level, the header portion further comprises a priority request section for carrying a priority request S representing a priority level requested at each of the slave node stations, and a priority section for carrying the highest priority level in the priorlty request ae an indication prlority level. The demultlplexing means separates the priority request section from the incoming 10 slot signal as a separated priority request. The master node station further comprises priority control means coupled to the demultiplexing means responsive to the separated priority request for detecting the highest priority level in the separated priority request as a 15 detected priority level to set the detected priority level in the priority section as the indication priority level. The priority control means sets a non-request code in the priority requ~st s~ction.
The control ~eans in each of the slave node 20 stations monitors the transmission buffer means to detect a particular one of the priority levels requested by the buffered data signal in the transmission buffer means as a particular priority request. Each of the slave node stations further comprises priority register 25 means coupled to the control means for holding the particular priority request; and priority request processing means coupled to the demultiplexing means and the priority register means for producing a specific . .
' 2~8~
priority request from the particular priority request and the separated priority request to deliver the specific priority request as another one of the input signals to the multiplexing means.
S In each of the slave node station, the demultiplexing means demultiplexes the priority section in the incoming slot signal as a separated priority signal. The separated priority signal is delivèred as another of the input signals to the multiplexing means.
10 The control means responsive to the separated priority signal compares the indication priority level of the separated priority signal with the particular priority request level and make~ the token processing means be in the non-token condition when the particular priority lS request level is equal to or higher than the indication priority level of the ~eparated priority signal.
When the priority is divided into N ~N being an integer) levels from the minimum lavel to tha maximum level, the priority request is represented by a binary 20 code of N digits with "1" in different digits representing different priority levels so that "1" of the highest and the lowest digits represents the maximum and the minimum levels. The priority request processing means comprises means for writing "1" into a particular 25 digit in the separated priority request signal corresponding to the particular priority request.
2~187~9 Brief Description of the drawings:
Fig. 1 is a diagram view of a token passing type slotted loop network system to which the present invention is applicable;
S Fig. 2 is a view illustrating a slot format used in an embodiment of the present invention;
Flg. 3 i~ a bloek dlag~m o~ a ma~ter node gtation in the loop network in Fig. 1 according to an embodiment of the present invention;
Fig. 4 is a block diagram of a slave node station in the loop network in Fig. 1 according to the embodiment of the present invention;
Fig. 5 is a flow chart illustrative of operation of priority control in the master node station in 15 Fig. 4;
Fig. 6 i9 a flow chart illustrative of operation of priority request processor in each node station in Fig. 4;
Fig. 7 is a flow chart illustrative of operation 20 for acquiring a token by each node station in Figs. 3 and 4;
Fig. 8 is a flow chart illustrative of operation for transmitting data in a node station in Figs. 3 and 4;
Fig. 9 is a diagram view illustrating a data frame in a node station and a slot sent out from the node station;
2 0~8~1~
Fig. 10 is a diagram view illustrating another data frame in a node station and slots sent out from the node station; and Fig. 11 is a diagram view illustrating slot 5 transmitting operation in adjacent node stations.
Description of Preferred Embodiments~
Referring to Fig. 1, a token passing type slotted loop network system oomprises a plurality of node sta~ions ~our stations 11 through 14 are 10 exemplarily shown) connected through transmission lines to form a ring or loop 15, as well known in the prior art. The first (#l) node station 11 is a master station and the other second through fourth (#2 - #4) node stationq 12-14 are slave node stations.
A plurality of slots circulates on the loop 15 under control by the master node station 11 and repetition at each of the slave node stations 12-14.
Referring to Fig. 2, each slot has a format of a fixed length which comprises a header por~ion 1~ o 20 eight ~8) bytes an,d a user's data carrier portion 17 of forty-eight (48) bytes. The header portion 16 comprises a logical network identification (ID) field 18 of one byte, an access control field (ACF) 19 of two (2) bytes, a VCI field 20 of four (4) bytes and a header error 25 correction field 21 of one byte.
The logical network ID portion 18 is for carrying an identifier representative of a logical network type used in the network system.
The ACF field 19 is for carrying access control data and comprises a slot type identifier (SL TYPE) section 22, a priority request section 23, a busy/idle (BUSY) section 24, an end mark (END) section 25, a 5 chaining code (CHAIN) section 26, a master/slave (MASTER) section 27, a token/non-token (TOKEN) section 28, and a priority section 29.
The slot type identi~ier sea~ion 22 is for carrying a code representative of a type of the user's 10 data signal which is ~ransmitted by the same slot.
There are two types for the user's data signal, that is, a simple packet type and an ATM type as described in the preamble. The slot type identifier is a one-bit code and ~0" and "1" of the code represent, for example, the 15 simple packet type and the ATM type, respectiveiy.
The priority request section 23 is for carrying a priority request signal (PRI-REQ) of a request code representing priority levels requested in node stations.
The request code has a four-bit length in the present 20 embodiment. The priority is divided into four levels, that is, the minimum level "I" through the maximum level "IV" which are corresponding to "1" of the lowest digit through the highest digit of the four-bit request code, respectively. Therefore, the four priority levels "I' 25 to "IV" are represented by "0001" to "1000" which are called first through fourth requested level code Rl to R4. The requested level codes Rl to R4 are collectively called the request code R.
2018~g The busy/idle section 24 is for carrying a one bit code signal representing whether the same slot is busy or idle. The code is "l" when the slot is busy but is "0" when the slot is idle.
The end mark section 25 is for carrying an end/non-end signal of one bit representing whether or not the same slot i9 the last one for transmitting the current user'~ data signal . When the end/non-~nd signal is UlU, the signal means that the same slot is the last lO one and is called an end mark signal El. When the end/non-end signal is "0", the signal means that the same slot is not the last one and is called a non-end mark signal E0.
The chaining code section 26 is for carrying a lS chaining code signal of two-bit length which identifies a section of the current user's data signal transmitting the same slot. When the current user's data signal is wholly transmitted in the same tlme slot, the chaining code is "00" and is called a single code signal C0. The 20 current user's data signal is the ATM type signal, the chaining code signal is the single code signal C0. When the current user's data signal is a comparatively large length so that it should be divided into a plurality of data sections which are transmitted by a plurality of 25 subsequent slots, a start code "lO" signal Cl and a last code "01" signal C3 are given in the individual chaining code sections of the first and the last slots for transmitting the first and the last data sections, 13 201871~
respectively, and an intermediate code "11" signal C2 is given in the chaining code section or sections of intermediate slot or slots for transmitting intermediate data section or sections.
The master/slave section 27 is for carrying a code of one bit representing which the same slot is used by, the master or the slave node station, When the same slot is used by the master node sta~ion, the code is "1"
and is called a master code Ml. While, the code i9 ~0~
10 and i9 called a slave code M0 when the same slot is used by any one of the slave node stations.
The token/non-token section 28 is for carrying a token/non-token signal of one bit. The token signal Tl has a token code ~1", while the non-token signal T0 has 15 a non-token code "0". In the known manner, the token signal Tl is in only one of the slots on the loop when no node station acquires the transmission right, while it is not in an~ one of the slots on the loop when one of the node stations has the transmission right.
20 However, it should be noted that the token signal Tl is inserted in the header portion 16 in one of the slots.
The priority section 29 is for carrying a priority signal (PRI) as an indication priority level representative of the highest priority level in the 25 priority request section 23 written during a previous complete circulation of the same slot through the loop.
Since the priority is divided into four levels "I"
through "IV" as described above, the priority levels "I"
2 0~871~
through "IV" are represented by binary codes "00"
through "11". Those binary codes are referred to as priority level codes PO through P3, respectively, and are collectively called a priority code P.
S Referring to Fig. 3, the master node station 11 comprises a demultiplexer 31 for demultiplexing each one of a sequence of 410ts incoming through the loop 15 to produce the priority signal (PRI), the priority request slgnal 'PRI-REQ), the token/non-token signal (TOKEN), 10 the end/non-end signal (END MARK), and the remaining portion of the slots as a data portion signal.
The master node station 11 further comprises a reception buffer 32, a transmission buffer 33, a buffer controller 34, an access controller 35, a priority 15 controller 36, a register 37, a token processor 38, an end-mark processor 39, a data selector 40, and a multiplexer 41.
The reception bufer 32 temporarily holds the incoming slot signal and sends out the user' 9 data 20 portion in the incoming slot signal to a terminal (not shown) accommodated in the master node station 11 when the user's data signal in the user's data carrier portion of the incoming slot is destined to the terminal under control of the buffer controller 34.
The transmission buffer 33 temporarily stores a data signal as a buffered data signal from the terminal accommodated in the master node station 11. The buffer controller 34 monitors the transmission buffer 33 to 2018~19 detect the buffered data signal therein to be transmitted to the loop and delivers information for access control to the access controller 35.
The access controller 35 controls the buffer 5 controller 34, the priority controller 36, the token processor 38, the end-mark processor 39, and the data selector 40 in the manner as will later be described.
The multiplexer 41 receives the priority signal ~PRI) from the register 37, the prlority request signal 10 (PRI-REQ) from the priority controller 36, the token signal from the token processor 38, the end/non-end signal (END MARK) from the end-mark processor 39, and the data signal from the data selector 40, and produces a new slot signal having the format shown in Fig. 2 lS which i9 delivered to the loop lS.
When the master node station does not have the token, the token processor 38, the end-mark processor 39 and the data 9elector 40 transfer the token/non-token signal ~, the end/non-end signal E and the other data 20 portion signal, respectively, from the demultiplexer 31 to the multiplexer 41.
The master node station 11 is provided with a delay controller 42 as a stage prior to the demultiplexer 31. The delay controller 42 is for 25 controlling a loop delay of each slot to be equal to an integer time of the slot length.
Referring to Fig. 4, each of the slave node stations 12-14 is similar to the master node station 11 16 :20~$7~
and the similar portions are represented by the same reference numerals in Fig. 3. That is, the slave node station comprises the demultiplexer 31, the reception buffer 32, the transmission buffer 33, the buffer 5 controller 34, an access controller 35', the token processor 38, the end-mark processor 39, the data selector 40, and the multiplexer 41. The slave node ~tation further comprlses a priority register 42 and a priority request processor 43 in place of the priority 10 controller 36 and the register 37 in the master node station 11.
The access controller 35' in the slave node station is similar to the access controller 35 in the master node station but different in that the former 15 controls the priority register 42 and the priority request processor 43 in place of the priority controller 36 and the register 37 in the master node station 11.
Thereafter, the acCess controller in each o the slave node station is represented by not 35 but 35'.
When each of the slave node station has no data signal to be transmitted, the priority request processor 43, the token processor 38, the end-mark processor 39 and the data selector 40 are at a repeating condition and transfer the priority request signal, the 25 token/non-token signal, the end/non-end signal and the other data signal from the demultiplexer 31 to the multiplexer 41. Further, the priority signal is directly transferred from the demultiplexer 31 to the 201871;9 multiplexer 41. Therefore, the each of the slave node station repeat the incoming slot signal.
Returning to Fig. 3 and additionally referring to Fig. 5, description is made as to operation of the 5 priority controller 36 and the register 37 in the master node ~tation 11. On start of the ~ystem, the priority controller 3~ produces a non-request code RO ~0000) as the priority request signal (PRI-REQ), as shown at a step 51 in Fig. 5. Then, the multiplexer 41 multiplexes 10 the priority request signal (PRI-REQ) with other signals to form a slot signal which is delivered to the ioop 15.
The slot circulates the loop 15 and i5 received at the demultiplexer 31 in the master node station 11 as a returned slot signal. During the circulation, each of 15 the slave node stations 12-14 writes into the priority request section of the slot the request code R generated ln each slave node station. ~he demultiplexar 31 ln the mastQr node station 11 separates the priority request section from the returned slot signal to produce the 20 priority request signal (PRI-REQ) which is received at the priority controller 36 as shown at a step 52. Then, the priority controller 36 generates a priority code P
as the indication priority corresponding to the highest level of the request code R in the priority request 25 signal (PRI-REQ) and writes the priority code P into the register 37. The register 37 delivers the priority code P as the priority signal (PRI) to the multiplexer 41, as shown at a step 53. The priority controller 36 again 18 2~1-8~
produces the non-request code R0 which is also delivered to the multiplexer 41. Then, a new slot is formed and delivered from the multiplexer 41 to the loop. The priority signal and the priority request signal are set 5 in the header of the new slot. Thereafter, similar operation is repeated.
Referring to Figs. 4 and 6, description ls now made as to operation of the priority request processor 43 under control of the priority register 42 and the 10 access controller 35' in each of the slave node stations 12-14.
When the transmission buffer 33 holds the user's data signal to be transmitted to the loop, the access controller 35' detects a priority level of the user's 15 data signal through the buffer controller 34. Then, the access controller 35' produces the request code R
corresponding to the priority level and delivers the request code R to the priority register 42. The priority register 42 supplies the request code R to the 20 priority request processor 43.
The slot delivered to the loop from the master node station 11 is received at the demultiplexer 31 in the slave node station. The demultiplexer 31 separates the priority request section in the slot and produces 25 the priority request signal (PRI-REQ) which is applied to the priority request processor 43 at a step 54 in Fig. 6.
2~71.~
The priority request processor 43 comprises four OR gates 431 through 434 which are corresponding to the highest bit through the lowest bit of the request code R. The priority request signal (PRI-REQ) of four bits 5 are applied to individual input terminals of OR gates 431-434 while four bits request code R are applied to lndivldual second input terminals o~ OR gates 431-434.
Therefore, the request code R is combined with the priority request signal (PRI-REQ) at a step SS to 10 produce a fresh one of the priority request signal IPRI-REQ).
In the node station, when the request code R is, for example, R1 (0001), the R1 is combined with the non-request code RO (0000) of the received priority lS re~ue~t signal (PRI-REQ), a code of the priority request signal is changed into a combined priority request code (RO~R1) or (0001).
~he combined or changed priority request -4ignal (PRI-REQ) is supplied to the multiplexer 41 at a step 56 20 and is multiplexed with the other repeated signals to rep.roduce the slot which is delivered to the loop.
At the downstream slave node station, when the request code R is, for example, R3 (0100), the code of the combined priority request (RO+Rl) received thereat 25 is combined with R3 and is changed into another modified priority request (R0+Rl+R3) or (0101) in the similar manner as described above.
~ ....
Thereafter, the node station monitors the priority signal (PRI) in the slot received thereat.
Referring to Fig. 7, the access controller 35' monitors the priority signal (PRI) in the incoming slot 5 signal stored in the reception buffer 32 through the buffer controller 34 at a step 57. The priority level ind~cated by the monitored prio~ity signal ~PRI) is compared with thè own priority level requested by the subscriber's data signal stored in the transmission 10 buffer 33 at a step 58. When the former is lower than the latter, the access controller 35' makes the token processor 38 acquire the token code Tl at a step 59.
The token processor 38 comprises an OR gate 381 and an AND gate 382. The token/non-token signal T
15 separated from the incoming slot at the demultiplexer 31 is applied to a Pirst input terminal of the OR gate 381.
An output of the OR gate 381 is coupled to a first input terminal of the AND gate 382. Second input terminals of the OR gate 381 and the AND gate 382 are coupled to the 20 access controller 35'. The token/non-token signal T is also applied to the access controller 35'. Normally, the access controller 35' supplies an OR gate control signal with a level "0" and an AND gate control signal with a level "1" to the second input terminals of the OR
25 gate 381 and the AND gate 382, respectively. Therefore, the token processor 38 is set in a repeating condition and repeats the token/non-token signal from said demultiplexer 31.
21 ~018~
At step 59, the access controller 35' changes the AND gate control signal from level "1" to level "0"
to set the token processor 38 in a non-token condition.
Accordingly, the AND gate 382 produces the non-token S code signal T0 of "0" level as the token/non-token slgnal T. The non-token code signal T0 is carried in the token/non-token section (~8 in Fig. 2) of tlle slot delivered from the multiplexer 41, whether the OR gate 381 produces "1" level signal or "0" level signal.
Thereafter, when the access controller 35' detects the token code Tl in the token/non-token signal T applied from the demultiplexer 31 at a step 60 in Fig.
8, the access controller 35' delivers a switch signal S
to the data selector 40 so as to connect the 15 transmission buffer 33 to the multiplexer 41 and a grant signal to the buffer controller 34 so as to start transmlssion of the subscriber's data signal stored in the transmission buffer 33 at step 61 in Fig. 8.
The user's data signal in the transmission 20 buffer 33 is transmitted by a single slot or a plurality of subsequent slots as described above.
The access controller 35' monitors the transmission buffer 33 through the buffer controller 34 to detect whether or not a plurality of slots are 25 required for transmission of the user's data signal at a step of 62.
When a plurality of slots are required, the transmission buffer 33 holds the user's data signal .
together with the start code Cl, the last code C3 and the intermittent code C2 which are carried in the chaining code section in individual slots delivered from the multiplexer 41.
Thereafter, the access controller 35' monitors through the buffer controller 34 at a step 63 whether or not the final slot iq started from transmission of the buffered data in the transmissi~n buer 33. When the flnal slot i9 started, the access controller 35' drives 10 the end mark processor 39 to produce the end mark El at a step 64.
The end mark processor 39 comprises an AND gate 391 and an OR gate 392. The AND gate 391 has a first input terminal connected to the demultiplexer 31 for 15 receiving the end/non-end signal E separated from the incoming slot signal by the demultiplexer 31. The AND
gate 391 has an output terminal which i9 connected to a first input terminal of the OR gate 392. Second input terminals of the AND gate 391 and the OR gate 392 are 20 connected to the access controller 35' for receiving control signals therefrom. Normally, the access controller 35' supplies an AND gate control signal with a level "1" and an OR gate control signal with a level "0" to the second input terminals of the AND gate 391 25 and the OR gate 392, respectively. Therefore, the end-mark processor 39 is maintained at a repeating condition and the end/non-end signal E from the demultiplexer 31 is repeated. The access controller 35' 2~,8~
is also supplied with the end/non-end signal E from the demultiplexer 31.
At step 64, the access controller 35' changes the OR gate control signal from "0" level to "1" level 5 to make the end-mark processor be in an end condition.
Therefore, the OR gate 392 produces the end mark signal El of "1" le~el whether the output of the AND gate 391 is level "0" or "1" signal.
When the user's data signal can be transmitted 10 by a single slot, or the user's data signal is the ATM
signal, the transmission buffer 33 holds the user's data signal together with the single code C0 which is carried in the chaining code section in the slot delivered from the multiplexer 41. Then, the end mark El is also 15 produced at step 64.
Thereafter, the access controller 35' çontrols the token processor 38 lnto a token condition by changing the AND gate aontrol signal from "0" level to "1" level and by supplying the OR gate control signal of 20 a level "1" signal to the OR gate 381. Accordingly, the token code signal Tl of ~1" is produced and delivered to the multiplexer 41 at step 65. Thereafter, the access controller 35' makes the token processor be in the repeating condition.
The end mark code signal El and the token code signal Tl are carried in the end/non-end signal section 25 and the token/non-token section 28 in the header 20~871~
portion 16 of the slot delivered from the multiplexer 41.
Then, the transmission of the user's data signal is completed.
Fig. 9 illustrates transmission of an ATM packet signal by use of a single slot. The ATM signal 70 has a frame which comprises a label section comprising VCI
tvirtual cirauit indiaat~r) and a data section comprising an information field INFO and a frame check 10 sequence FCS. The slot for transmitting the ATM packet signal has the header portion 16 including the end mark signal El, the single code signal CO, the token code signal T1 and the VCI, and the data portion carrying the INFO and the FCS. The header of the next subsequent 15 slot is shown in the figure and includes the non-end mark signal EO, the single code CO and the non-token signal TO.
Fig. 10 illustrates transmission o a simple packet signal 71 as the user's data signal by use of 20 three slots.
The signal 71 is divided into three blocks I, II
and III which are carried in individual data carrier portions 17 in the three slots. As shown in the figure, the non-end signal EO, the non-token signal TO and the 25 start code Cl are carried in the header 16 ln the first slot. The non-end signal EO, the non-token signal TO
and the intermediate signal C2 are carried in the header in the second slot. The header of the third or final 201871~
slot has the end mark signal El, the final code signal C3 and the token signal Tl.
The header of tha next subsequent slot has the non-end mark signal E0, the single code C0 and the 5 non-token signal T0 like the slot shown in Fig. 9.
After the final slot is sent out from the multiplexer 41, the access controller 35' of the ~ame node 8tation detects the end mark signal El through the demultiplexer 31 at a step 66 in Fig. 8. Then, the 10 access controller 35' delivers an idler signal to the data selector 40 so as to restore the data selector 40.
Accordingly, the data selector 40 again couples the demultiplexer 31 to the multiplexer 41 90 that the data portion is repeated from the demultiplexer 31 .tb the lS multiplexer 41.
During a time period from step 61 to step 67 when the data selector 40 is switched onto the transmission buffer 33, incoming slot~ to the ~ame node ~tation ara stripped.
Furthermore, since the token signal Tl is inserted in the final slot for transmission of the user's data signal at step 65, the next downstream node station can acquire the token signal Tl just after the next upstream node station aborts the transmission right 25 by sending out the token signal Tl.
In the example of Fig. 10, the transmission buffer 33 holds a data signal and transfers the data signal by use of three slots. However, when the ~ ~18~1~
transmission buffer 33 holds several data signals as the buffered data signal and continuously transfers those several data signals, the last code signal C3 is carried by an individual last one of slots for transferring each 5 of the several data signals. However, the end mark signal El and the token signal Tl are not carried in all of the individual last slot and are only carried in the final one of ~lots for transerring the entire of the several data signals.
In the described embodiment, the token signal Tl is set in the final slot for transmission of the buffered data signal. However, the non-token signal T0 can be maintained in the final slot and the token signal Tl is freed in the next subsequent slot after the final lS slot. The case is shown by representations of (T0) and (Tl) in Figs, 9 and 10.
Referring to Fig. 11, description is made as to an exemplary case where ~2 node station 12 sends out three slots 121-123 thereafter #3 node station 13 sends 20 out four slots 131-134. At (b) in Fig. 11, the node station 12 delivers the three slots 121-123 to the loop.
The slots 121-123 are received by the node station 13 at (c). Then, the node station 13 can capture the token signal Tl. Therefore, the node station 13 repeats the 25 slots 121-123 and transmits the slots 131-134 at td).
The slots 121-123 and 131-134 are received by the node station 12 at (a). The node station 12 is set in a slot stripping condition during a time duration Dl from the 20187~
transmission start of slots 121-123 at (b) to the reception completion of the slots 121-123 at (a).
Thereafter, the node station repeats the slots 131-134 to the node station 13 at (b). Then, the node 5 station 13 receives the slots 131-134. The node station 13 is set in a slot stripping condition during a time duration D2 from the transmission 8tart of slots 131-134 at ~d) to the reception complation o the slot~ 131-134 at (c).
Therefore, slot stripping can readily be performed by use of the end mark signal without use of any address information.
Claims (9)
1. A token passing type slotted loop network system comprising a master node station and a plurality of slave node stations connected to each other to form a data transmission loop, a plurality of slots being circulated on said loop for transmitting a data signal from a particular one of the node stations having the token, each of said slots having a fixed length and comprising:
a header portion comprising an end/non-end code section for carrying the end/non-end code, the end code and the non-end code representing an end and a non-end of transmission of the data signal; and a data carrier portion for carrying the data signal, each of said master and slave node stations comprising:
multiplexing means for multiplexing input signals applied thereto to produce a multiplexed signal, said multiplexed signal being delivered therefrom to the loop;
transmission buffer means for holding the data signal to be transmitted to the loop as a buffered data signal as one of said slots;
demultiplexing means for demultiplexing each of said slots sequentially incoming thereto as an incoming slot signal to produce said end/non-end code section and (Claim 1 continued) a remaining portion as a separated end/non-end signal and a separated data signal;
selecting means coupled to said demultiplexing means and said transmission buffer means for selecting said separated data signal at a repeating mode and said buffered data signal at a transmission mode as a selected signal, said selected signal being delivered to said multiplexing means as one of said input signal;
end-mark processing means coupled to said demultiplexing means for repeating said separated end/non-end signal to said multiplexing means as another one of said input means at a repeating condition, said end-mark processing means producing the non-end code signal and the end code signal to deliver the non-end code signal and the end code signal to said multiplexing means as another input signal at a non-end condition and an end condition, respectively; and control means coupled to said demultiplexing means, said transmission buffer means, said selecting means and said end-mark processing means for controlling said end-mark processing means and said selecting means.
a header portion comprising an end/non-end code section for carrying the end/non-end code, the end code and the non-end code representing an end and a non-end of transmission of the data signal; and a data carrier portion for carrying the data signal, each of said master and slave node stations comprising:
multiplexing means for multiplexing input signals applied thereto to produce a multiplexed signal, said multiplexed signal being delivered therefrom to the loop;
transmission buffer means for holding the data signal to be transmitted to the loop as a buffered data signal as one of said slots;
demultiplexing means for demultiplexing each of said slots sequentially incoming thereto as an incoming slot signal to produce said end/non-end code section and (Claim 1 continued) a remaining portion as a separated end/non-end signal and a separated data signal;
selecting means coupled to said demultiplexing means and said transmission buffer means for selecting said separated data signal at a repeating mode and said buffered data signal at a transmission mode as a selected signal, said selected signal being delivered to said multiplexing means as one of said input signal;
end-mark processing means coupled to said demultiplexing means for repeating said separated end/non-end signal to said multiplexing means as another one of said input means at a repeating condition, said end-mark processing means producing the non-end code signal and the end code signal to deliver the non-end code signal and the end code signal to said multiplexing means as another input signal at a non-end condition and an end condition, respectively; and control means coupled to said demultiplexing means, said transmission buffer means, said selecting means and said end-mark processing means for controlling said end-mark processing means and said selecting means.
2. A token passing slotted loop network as claimed in Claim 1, wherein, in said particular node station, said control means makes said end-mark processing means and said selecting means be in said non-end condition and in said transmission mode, respectively, said control means monitoring said (Claim 2 continued) transmission buffer means and making said end-mark processing means be in said end condition to produce said end code signal at an end of transmission of said buffered data signal, said control means making said end-mark processing means and said selecting means be in said repeating condition and in said repeating mode, respectively, when said control means detects that said demultiplexed end/non-end signal is said end code signal, and wherein, in each of the node stations other than said particular node station, said control means makes said end-mark processing means and said selecting means be in said repeating condition and in said repeating mode, respectively.
3. A token passing slotted loop network as claimed in Claim 2, wherein said header portion further comprises a token/non-token code section for carrying one of a token code representing the token and a non-token code, said demultiplexing means separating said token/non-token code section from said incoming slot signal to produce a separated token/non-token signal, and wherein each of said master and said slave node stations further comprises token processing means coupled to said demultiplexing means for repeating said separated token/non-token signal to said multiplexing means as another one of said input signals at a repeating condition, said token processing means producing the non-token code signal and the token code (Claim 3 continued) signal to deliver the non-token code signal and the token code signal at a non-token condition and a token condition, respectively, to said multiplexing means as another input signal, said control means controlling said token/non-token processing means.
4. A token passing slotted loop network as claimed in Claim 3, wherein said control means makes said token processing means be in said non-token condition in order to acquire the token when detecting that said transmission buffer means holds said buffered data signal, said control means acquiring the token when detecting that said separated token/non-token signal is said token code signal, and said control means, as said control means in said particular node station, making said end-mark processing means and said selecting means be in said non-end condition and said transmission mode.
5. A token passing slotted loop network as claimed in Claim 4, wherein, in said particular node station, said control means makes said token processing means be in said token condition so as to free the token at the end of transmission of said buffered data signal and then makes said token processing means into said repeating condition.
6. A token passing slotted loop network as claimed in Claim 4, said data signal having a priority of one of different priority levels from a minimum level and a maximum level, wherein said header portion further (Claim 6 continued) comprises a priority request section for carrying a priority request representing a priority level requested at each of said slave node stations, and a priority section for carrying the highest priority level in said priority request as an indication priority level, said demultiplexing means separating said priority request section from said incoming slot signal as a separated priority request, and wherein said master node station further comprises priority control means coupled to said demultiplexing means responsive to said separated priority request for detecting the highest priority level in said separated priority request as a detected priority level to set said detected priority level in said priority section as said indication priority level, said priority control means setting the minimum level in said priority request section.
7. A token passing type slotted loop network as claimed in Claim 6, said control means in each of said slave node stations monitoring said transmission buffer means to detect a particular one of the priority levels requested by said buffered data signal in said transmission buffer means as a particular priority request, wherein each of said slave node stations further comprises priority register means coupled to said control means for holding said particular priority request; and priority request processing means coupled to said demultiplexing means and said priority register (Claim 7 continued) means for producing a specific priority request from said particular priority request and said separated priority request to deliver said specific priority request as another one of said input signals to said multiplexing means.
8. A token passing type slotted loop network system as claimed in Claim 7, wherein, in each of said slave node station, said demultiplexing means demultiplexes said priority section in said incoming slot signal as a separated priority signal, said separated priority signal being delivered as another of said input signals to said multiplexing means, said control means responsive to said separated priority signal for comparing said indication priority level of said separated priority signal with said particular priority request level, said control means making said token processing means be in said non-token condition when said particular priority request level is equal to or higher than said indication priority level of said separated priority signal.
9. A token passing type slotted loop network system as claimed in Claim 7, said priority being divided into N (N being an integer) levels from said minimum level to said maximum level, said priority request being represented by a binary code of N digits with "1" in different digits representing different priority levels so that "1" of the highest and the (Claim 9 continued) lowest digits represents the maximum and the minimum levels, wherein said priority request processing means comprises means for writing "1" into a particular digit in said separated priority request signal corresponding to said particular priority request.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP147541/1989 | 1989-06-09 | ||
| JP14754289A JPH0313031A (en) | 1989-06-09 | 1989-06-09 | Access control system for loop network |
| JP147542/1989 | 1989-06-09 | ||
| JP14754189A JPH0828734B2 (en) | 1989-06-09 | 1989-06-09 | Data transfer control method for slotted loop network |
| JP18305189A JPH0346849A (en) | 1989-07-14 | 1989-07-14 | Priority control system for loop network |
| JP183051/1989 | 1989-07-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2018719A1 CA2018719A1 (en) | 1990-12-09 |
| CA2018719C true CA2018719C (en) | 1993-12-21 |
Family
ID=27319370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002018719A Expired - Fee Related CA2018719C (en) | 1989-06-09 | 1990-06-11 | Token passing type slotted loop network system with means for enabling high speed access control and simple frame slot stripping |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5070501A (en) |
| CA (1) | CA2018719C (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5274637A (en) * | 1989-12-28 | 1993-12-28 | Yamaha Corporation | Token-ring-type local area network |
| AU1061892A (en) * | 1991-02-06 | 1992-08-13 | Fmc Corporation | Access to transmit on a message priority basis |
| US5341374A (en) * | 1991-03-01 | 1994-08-23 | Trilan Systems Corporation | Communication network integrating voice data and video with distributed call processing |
| US5216670A (en) * | 1991-07-03 | 1993-06-01 | International Business Machines Corporation | Message stripping protocol for a communication network |
| US5784631A (en) * | 1992-06-30 | 1998-07-21 | Discovision Associates | Huffman decoder |
| US5535212A (en) * | 1992-12-21 | 1996-07-09 | Otis Elevator Company | Implicit token media access protocol without collision detection |
| US5317565A (en) * | 1993-01-26 | 1994-05-31 | International Business Machines Corporation | Method of sequencing bus operations in a simplex switch |
| GB2295070B (en) * | 1994-11-09 | 1999-11-17 | Alps Electric Co Ltd | Multiplex communication system |
| DE19549462C2 (en) * | 1994-11-09 | 2003-07-03 | Alps Electric Co Ltd | Multiplex communication system e.g. for vehicle |
| EP1016244B1 (en) * | 1997-09-17 | 2007-04-18 | BRITISH TELECOMMUNICATIONS public limited company | Communications network |
| GB2338155B (en) * | 1998-06-05 | 2003-02-12 | 3Com Technologies Ltd | Hub system with ring arbitration |
| DE102006040709B4 (en) * | 2006-08-30 | 2008-08-14 | Sick Ag | Data transmission method in a daisy chain arrangement |
| DE102010041427A1 (en) | 2010-09-27 | 2012-03-29 | Robert Bosch Gmbh | Method for transmitting data |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4709364A (en) * | 1984-07-25 | 1987-11-24 | Sumitomo Electric Industries, Ltd. | Network priority determining method |
| GB2175774B (en) * | 1985-05-24 | 1988-09-01 | Stc Plc | Intelligence transmission system of the local area network type |
| JPS6468156A (en) * | 1987-09-09 | 1989-03-14 | Nec Corp | Data transfer system |
| JPH0198343A (en) * | 1987-10-12 | 1989-04-17 | Nec Corp | Data transmission system for loop transmission system |
| US4932023A (en) * | 1989-06-20 | 1990-06-05 | International Business Machines Corporation | Frame stripping protocol for early token release in a ring communication network |
-
1990
- 1990-06-11 US US07/535,619 patent/US5070501A/en not_active Expired - Fee Related
- 1990-06-11 CA CA002018719A patent/CA2018719C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2018719A1 (en) | 1990-12-09 |
| US5070501A (en) | 1991-12-03 |
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