V120 Layer 2
V120 frame structure: fields
The structure of frame is that specified in Q921:
| bits 8 _ _ _ _ _ _ 1 |
field |
| octet 1 |
Address (High order octet) |
| octet 2 |
Address (Low order octet) |
| octet 3 |
Control |
| octets 4-n |
Information |
The structure of Information field is:
| bits 8 _ _ _ _ _ _ 1 |
Information field |
| octet 1 |
H: terminal adaption Header |
| octet 2 |
CS: optional header extension for control state information |
| octets 3-n |
V120 Information |
Address field
| - Octet 1: |
|
| bits 8-3 |
LLI0 (bits 13-8 of LLI logical link identifier) |
| bit 2 |
C/R: Command/Response |
| bit 1 |
Address field extension (0) |
|
|
| - Octet 2: |
|
| bits 8-2 |
LLI1 (bits 7-1 of LLI logical link identifier) |
| bit 1 |
Address field extension (1) |
| LLI value |
Logical link identifier |
| 0 |
In channel Signalling |
| 1-255 |
Reserved for future standardization |
| 256 |
Default LLI |
| 257-2047 |
For LLI assignment |
| 2048-8190 |
Reserved for future standardization |
| 8191 |
In channel layer management |
| C/R value |
Meaning |
| 0 |
Command |
| 1 |
Response |
Control field
As Q921 frame structure: control field.
| 