ANSI T1.618
Reference Standard: ANSI T1.618.
T1.618 frame structure: fields
| bits 8 _ _ _ _ _ _ 1 |
field |
| octets 1-i |
Address ( 2, 3 or 4 octets) |
| octet i+1 |
Control |
| octets (i+2)-n |
Information |
CLLM (Consolidated Link Layer Management) message.
| bits 8 _ _ _ _ _ _ 1 |
field |
| octets 1-i |
Address ( 2, 3 or 4 octets) |
| octet i+1 |
AFh = XID control field |
| octet i+2 |
82h = Format identifier |
| octet i+3 |
0Fh = Group identifier |
| octet i+4 |
Group length octet 1 |
| octet i+5 |
Group length octet 2 |
| octet i+6 |
00h = Parameter identifier |
| octet i+7 |
04h = Parameter length |
| octet i+8 |
105d =Parameter value (IA5 character ‘I’) |
| octet i+9 |
49d =Parameter value (IA5 character ‘1’) |
| octet i+10 |
50d =Parameter value (IA5 character ‘2’) |
| octet i+11 |
50d =Parameter value (IA5 character ‘2’) |
| octet i+12 |
02h = Parameter identifier |
| octet i+13 |
01h = Parameter length |
| octet i+14 |
Cause value |
| octet i+15 |
03h =Parameter value (DLCI identifier) |
| octet i+16 |
Parameter length |
| octets i+17-n |
DLCI value octets (1rst DLCI) |
|
DLCI value octets (ntht DLCI) |
T1.618 frame structure: address field
They are 3 possible formats for the address field:
Address field 2 octets
| - Octet 1: |
|
| bits 8-3 |
upper DLCI: Data Link Connection Identifier |
| bit 2 |
C/R: Command/Response |
| bit 1 |
Address field extension (0) |
| - Octet 2: |
|
| bits 8-5 |
lower DLCI: Data Link Connection Identifier |
| bit 4 |
FECN: forward explicit congestion notification |
| bit 3 |
BECN: backward explicit congestion notification |
| bit 2 |
DE: discard eligibility indicator |
| bit 1 |
Address field extension (1) |
Address field 3 octets
| - Octet 1: |
|
| bits 8-3 |
upper DLCI: Data Link Connection Identifier |
| bit 2 |
C/R: Command/Response |
| bit 1 |
Address field extension (0) |
| - Octet 2: |
|
| bits 8-5 |
DLCI: Data Link Connection Identifier |
| bit 4 |
FECN: forward explicit congestion notification |
| bit 3 |
BECN: backward explicit congestion notification |
| bit 2 |
DE: discard eligibility indicator |
| bit 1 |
Address field extension (0) |
| - Octet 3: |
|
| bits 8-3 |
lower DLCI or DL-CORE control |
| bit 2 |
D/C: DLCI (0) /DL-CORE (1) control indicator |
| bit 1 |
Address field extension (1) |
Address field 4 octets
| - Octet 1: |
|
| bits 8-3 |
upper DLCI: Data Link Connection Identifier |
| bit 2 |
C/R: Command/Response |
| bit 1 |
Address field extension (0) |
| - Octet 2: |
|
| bits 8-5 |
DLCI: Data Link Connection Identifier |
| bit 4 |
FECN: forward explicit congestion notification |
| bit 3 |
BECN: backward explicit congestion notification |
| bit 2 |
DE: discard eligibility indicator |
| bit 1 |
Address field extension (0) |
| - Octet 3: |
|
| bits 8-2 |
DLCI: Data Link Connection Identifier |
| bit 1 |
Address field extension (0) |
| - Octet 4: |
|
| bits 8-3 |
lower DLCI or DL-CORE control |
| bit 2 |
D/C: DLCI (0) /DL-CORE (1) control indicator |
| bit 1 |
Address field extension (1) |
T1.618 frame structure: control field
| - octet: |
|
| bits 8-6 |
M M M |
M: modifier function bit |
| bit 5 |
P/F |
Poll bit when issued as a command
Final bit when issued as a response |
| bits 4-3 |
M M |
M: modifier function bit |
| bits 2-1 |
1 1 |
|
| bits M : 876 - 43 |
Command |
Response |
Frame designation |
| 0 0 0 - 0 0 |
UI |
|
Unnumbered Information |
| 1 0 1 - 1 1 |
|
XID |
Exchange Identification |
The encoding values of the five M bits included in the first octet of the
control field can also be listed and ordered according to their hexadecimal
code.
| P=0 |
P=1 |
Type |
C/R |
Frame designation |
| 03 |
13 |
UI |
C/R |
Unnumbered Information |
| AF |
BF |
XID |
R |
Exchange Identification |
Note : Hexadecimal code corresponds to b8-b1 with P/F bit=0 or
P/F bit=1.
| 