Advanced Data Communication Control Procedures
{{Short description|Computer networking protocol}}
In telecommunications, 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 functionally equivalent to the ISO High-Level Data Link Control (HDLC) protocol.{{harvnb|Friend|Fike|Baker|Bellamy|1988|p=191}}
Although the ISO and ANSI standards writers coordinated their work, so the differences between the standards are mainly editorial, there is one meaningful difference: ADCCP's definition of the basic subset required to implement balanced asynchronous mode includes the RSET frame, while HDLC makes it optional.{{harvnb|NBS|1980|p=6|loc=§3.0 ADCCP classes of procedures}}
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. Like early versions of HDLC,{{harvnb|ISO|1984|p=18|loc=§7.4 Extended control field formats}} ADCCP specifies a 2-byte control field format with the P/F flag duplicated.{{harvnb|ANSI|1979|p=28|loc=§5.2.2 Extended control field}} Later HDLC specifications, in particular ISO/IEC 13239, changed that to specify that U frames have 1-byte control fields in all cases.
| class="wikitable" style="text-align:center"
|+ADCCP control fields !colspan=8| First byte | colspan=8| Second byte | rowspan=2| Description | |||||
| 0 || 1 || 2 || 3 || 4 || 5 || 6 || 7
! 0 || 1 || 2 || 3 || 4 || 5 || 6 || 7 | |||||||
|---|---|---|---|---|---|---|---|
| 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 send sequence number | ||
| 1 | 0 | colspan=2| type | P/F | colspan=3| N(R) | align=left| S frame, N(R) is a 3-bit receive sequence number | ||
| 1 | 1 | colspan=2| type | P/F | colspan=3| type | align=left| U frame | ||
| 0 | colspan=7| N(S) | P/F | colspan=7| N(R) | align=left| Extended I frame, N(S) is a 7-bit sequence number | |||
| 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 | |
| 1 | 1 | colspan=2| type | P/F | colspan=3| type | P/F | colspan=7 bgcolor=lightgrey| —0— | align=left| Extended U frame (ADCCP only) |
See also
References
{{Reflist}}
- {{cite book
|last1=Friend
|first1=George E.
|first2=John L.
|last2=Fike
|first3=H. Charles
|last3=Baker
|first4=John C.
|last4=Bellamy
|title=Understanding Data Communications
|edition=2nd
|year=1988
|publisher=Howard W. Sams & Company
|location=Indianapolis
|isbn=0-672-27270-9
}}
- {{cite book
|title=Guideline for implementing advanced data communication control procedures (ADCCP)
|publisher=National Bureau of Standards
|date=26 September 1980
|id=FIPS PUB 78
|ref={{harvid|NBS|1980}}
|url=https://archive.org/details/federalinformati78nati
}}
- {{cite book
|title=ISO 4335:1984 Data Communication—High Level Data Link Control Procedures—Consolidation of Elements of Procedures
|ref={{harvid|ISO|1984}}
|url=https://law.resource.org/pub/in/bis/S04/is.11418.2.1986.pdf
|archive-url=https://web.archive.org/web/20190323134103/https://law.resource.org/pub/in/bis/S04/is.11418.2.1986.pdf
|archive-date=23 March 2019
|url-status=live
}} [https://archive.org/details/gov.in.is.11418.2.1986 Alt URL]
- {{cite book
|title=ANSI X3.66-1979: American National Standard for advanced data communication procedures (ADCCP)
|publisher=American National Standards Institute
|date=9 January 1979
|id=FIPS PUB 71-1980
|url=https://archive.org/details/federalinformati7119nati
|ref={{sfnRef|ANSI|1979}}
}}
- {{FS1037C}}