Advanced Data Communication Control Procedures: Difference between revisions
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In [[telecommunication]], '''Advanced Data Communication Control Procedures''' (or '''Protocol''') ('''ADCCP''') is a [[bit |
In [[telecommunication]], '''Advanced Data Communication Control Procedures''' (or '''Protocol''') ('''ADCCP''') is a [[Bit-oriented protocol|bit-oriented]] [[data link layer]] [[Communication protocol|protocol]] developed by the [[American National Standards Institute]]. It is almost identical to the ISO [[High-Level Data Link Control]] (HDLC) protocol.<ref>{{harvnb|Friend|Fike|Baker|Bellamy|1988|p=191}}</ref> |
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Although the ISO and ANSI standards writers coordinated their work, there are differences between the standards. Most are editorial, but there are unintended differences between the defined subsets. |
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ADCCP is an [[American National Standards Institute|ANSI]] standard, X3.66, derived from [[IBM]]'s [[Synchronous Data Link Control]] (SDLC) protocol, and is functionally equivalent to the ISO [[High-Level Data Link Control]] (HDLC) standard.<ref>{{harvnb|Friend|Fike|Baker|Bellamy|1988|p=191}}</ref> |
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One major difference between the two is the unnumbered (U) format. When extended (7-bit) sequence numbers are used, I and S frames have two-byte control fields. HDLC, however, specifies that U frames have 1-byte control fields in all cases. ADCCP specifies a 2-byte control field format with the P/F flag duplicated:<ref>{{harvnb|X3.66|1979|p=28}}</ref> |
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ADCCP has 3 main modes – NRM (Normal Response mode akin to SDLC), ABM (Asynchronous Balanced mode - akin to HDLC) and ARM (Asynchronous Response mode) |
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{| class="wikitable" style="text-align:center" |
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|+ADCCP control fields |
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!colspan=8| First byte ||colspan=8| Second byte ||rowspan=2| Description |
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|- |
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! 0 || 1 || 2 || 3 || 4 || 5 || 6 || 7 |
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! 0 || 1 || 2 || 3 || 4 || 5 || 6 || 7 |
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|- |
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| 0 ||colspan=3| N(S) || P/F ||colspan=3| N(R) ||colspan=8 rowspan=3 bgcolor=lightgrey| ||align=left| I frame, N(S) is a 3-bit sequence number |
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|- |
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| 1 || 0 ||colspan=2| type || P/F ||colspan=3| N(R) ||align=left| S frame, N(R) is a 3-bit sequence number |
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|- |
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| 1 || 1 ||colspan=2| type || P/F ||colspan=3| type ||align=left| U frame |
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|- |
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| 0 ||colspan=7| N(S) || P/F ||colspan=7| N(R) ||align=left| Extended I frame, N(S) is a 7-bit sequence number |
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|- |
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| 1 || 0 ||colspan=2| type ||colspan=4 bgcolor=lightgrey| —0— || P/F ||colspan=7| N(R) ||align=left| Extended S frame, N(R) is a 7-bit sequence number |
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|- |
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| 1 || 1 ||colspan=2| type || P/F ||colspan=3| type || P/F ||colspan=7 bgcolor=lightgrey| —0— ||align=left| Extended U frame (ADCCP only) |
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|} |
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==See also== |
==See also== |
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* [[Data link layer]] |
* [[Data link layer]] |
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* [[High-Level Data Link Control]] |
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==References== |
==References== |
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|ref=harv}} |
|ref=harv}} |
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*{{cite book |
*{{cite book |
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|title=ANSI |
|title=ANSI X3.66-1979: American National Standard for advanced data communication procedures (ADCCP) |
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|publisher=[[American National Standards Institute]] |
|publisher=[[American National Standards Institute]] |
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|date=9 January 1979 |
|date=9 January 1979 |
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|id=FIPS PUB 71-1980 |
|id=FIPS PUB 71-1980 |
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|ref={{harvid|X3.66|1979}} |
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|url=https://archive.org/details/federalinformati7119nati |
|url=https://archive.org/details/federalinformati7119nati |
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}} |
}} |
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Revision as of 21:22, 7 November 2019
In telecommunication, Advanced Data Communication Control Procedures (or Protocol) (ADCCP) is a bit-oriented data link layer protocol developed by the American National Standards Institute. It is almost identical to the ISO High-Level Data Link Control (HDLC) protocol.[1]
Although the ISO and ANSI standards writers coordinated their work, there are differences between the standards. Most are editorial, but there are unintended differences between the defined subsets.
One major difference between the two is the unnumbered (U) format. When extended (7-bit) sequence numbers are used, I and S frames have two-byte control fields. HDLC, however, specifies that U frames have 1-byte control fields in all cases. ADCCP specifies a 2-byte control field format with the P/F flag duplicated:[2]
| First byte | Second byte | Description | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
| 0 | N(S) | P/F | N(R) | I frame, N(S) is a 3-bit sequence number | ||||||||||||
| 1 | 0 | type | P/F | N(R) | S frame, N(R) is a 3-bit sequence number | |||||||||||
| 1 | 1 | type | P/F | type | U frame | |||||||||||
| 0 | N(S) | P/F | N(R) | Extended I frame, N(S) is a 7-bit sequence number | ||||||||||||
| 1 | 0 | type | —0— | P/F | N(R) | Extended S frame, N(R) is a 7-bit sequence number | ||||||||||
| 1 | 1 | type | P/F | type | P/F | —0— | Extended U frame (ADCCP only) | |||||||||
See also
References
- ^ Friend et al. 1988, p. 191
- ^ X3.66 1979, p. 28
- Friend, George E.; Fike, John L.; Baker, H. Charles; Bellamy, John C. (1988). Understanding Data Communications (2nd ed.). Indianapolis: Howard W. Sams & Company. ISBN 0-672-27270-9.
{{cite book}}: Invalid|ref=harv(help) - ANSI X3.66-1979: American National Standard for advanced data communication procedures (ADCCP). American National Standards Institute. 9 January 1979. FIPS PUB 71-1980.
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22.
