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| High-Level Data Link Control (HDLC) | ||
| Link | Explanation | |
|---|---|---|
| 1 | User's manual | HDLC User's Manual. HDLC is decoded using dedicated settings of the general purpose decoder. In particular the NRZ or NRZ-S modes need to be selected, as well as the preamble synchronisation, CRC settings and bit un-stuffing mechanisms. Inquiries via info@lahniss.com |
| 2 |  |
Exemple of a decoded HDLC Frame. This compact trace shows an entire Frame of 52 words. The violet regions, at the beginning and the end of the trace, represent the Start and End Patterns used by HDLC to mark the payload span. |
| 3 |  |
At the bit level HDLC uses stuff bits. The stuffbits do not carry any information and need to be ignored by the decoding algorithm. |
| 4 |  |
Enlarged Start Pattern 0x7e. 0x7e translates to binary 0111 1110 and is visible in the analog trace, within the violet rectangle. Also note the stuff bit skip between byte 0x9f and 0x16. |
| 5 |  |
Enlarged End Pattern 0x7e. The 2 bytes before the End Pattern represent the 16 bit CRC used by HDLC to insure the Frame integrity. |
| HDLC (High-Level Data Link Control) references | ||
| Link | Explanation | |
|---|---|---|
| 1 | Wikipedia E | The excellent HDLC main page on Wiki. |
| 2 | Wikipedia D | The also excellent HDLC main page... auf Deutsch. The informations are not always the same in all languages, but can help on certain aspects |
| 3 | Wikipedia F | Comme pour l'allemand et l'anglais, la page francaise complete le tableau |
| 4 | Another view on HDLC | HDLC viewed in another context |
| 5 | Basic Frame Structure of HDLC | Basic Frame Structure of HDLC |
| 6 | HDLC: A Full Review | HDLC: A Full Review |
| 6 | HDLC: Im Netzwerkalltag verstehen | HDLC steht fuer High-Level Data Link Control und ist ein standardisiertes Protokoll der Sicherungsschicht (Layer 2) im OSI-Modell. Es wurde von der International Telecommunication Union (ITU-T) spezifiziert und ist insbesondere in Punkt-zu-Punkt-Verbindungen und WAN-Umgebungen verbreitet. HDLC dient dazu, Datenstroeme zwischen zwei Knoten zu rahmen, zu kontrollieren und sicher zu uebertragen. |
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