This section describes the clock source quality levels identified for tracking network timing flow in accordance with the network deployment options defined in Recommendation G.803 and G.781. The Option I network is developed on the original European SDH model; Option II network is a network developed on the North American SONET model.
In addition to the QL values received over SSM of an interface, the standards define the following additional codes for internal use:
QL INVx is generated internally by the system if and when an unallocated SSM value is received, where x represents the binary value of this SSM. Within the SR OS, these independent values are assigned as the single value QL-INVALID.
QL FAILED is generated internally by the system if and when the terminated network synchronization distribution trail is in the signal fail state.
The internal quality level of QL-UNKNOWN is used to differentiate from a received QL-STU code, but is equivalent for the purposes of QL selection.
The following table lists the synchronization message coding and source priorities for SSM values received on port.
SSM value received on port |
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|---|---|---|---|---|
SDH interface SyncE interface in SDH mode |
SONET interface SyncE interface in SONET mode |
E1 interface |
T1 interface (ESF) |
Internal relative quality level |
0010 (prc) |
0001 (prs) |
0010 (prc) |
00000100 11111111 (prs) |
1. Best quality |
0000 (stu) |
00001000 11111111 (stu) |
2. |
||
0111 (st2) |
00001100 11111111 (ST2) |
3. |
||
0100 (ssua) |
0100 (tnc) |
0100 (ssua) |
01111000 11111111 (TNC) |
4. |
1101 (st3e) |
01111100 11111111 (ST3E) |
5. |
||
1000 (ssub) |
1000 (ssub) |
6. |
||
1010 (st3/eec2) |
00010000 11111111 (ST3) |
7. |
||
1011 (sec/eec1) |
1011 (sec) |
8. Lowest quality qualified in QL-enabled mode |
||
1100 (smc) |
00100010 11111111 (smc) |
9. |
||
00101000 11111111 (st4) |
10. |
|||
1110 (pno) |
01000000 11111111 (pno) |
11. |
||
1111 (dnu) |
1111 (dus) |
1111 (dnu) |
00110000 11111111 (dus) |
12. |
Any other |
Any other |
Any other |
N/A |
13. QL_INVALID |
14. QL_FAILED |
||||
15. QL_UNC |
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The following table lists the synchronization message coding and source priorities for SSM values transmitted by interface type.
SSM values to be transmitted by interface of type |
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|---|---|---|---|---|
Internal relative quality level |
SDH interface SyncE interface in SDH mode |
SONET interface SyncE interface in SONET mode |
E1 interface |
T1 interface (ESF) |
1. Best quality |
0010 (prc) |
0001 (PRS) |
0010 (prc) |
00000100 11111111 (PRS) |
2. |
0100 (ssua) |
0000 (stu) |
0100 (ssua) |
00001000 11111111 (stu) |
3. |
0100 (ssua) |
0111 (st2) |
0100 (ssua) |
00001100 11111111 (st2) |
4. |
0100 (ssua) |
0100 (tnc) |
0100 (ssua) |
01111000 11111111 (tnc) |
5. |
1000 (ssub) |
1101 (st3e) |
1000 (ssub) |
01111100 11111111 (st3e) |
6. |
1000 (ssub) |
1010 (st3/eec2) |
1000 (ssub) |
00010000 11111111 (st3) |
7. |
1011 (sec/eec1) |
1010 (st3/eec2) |
1011 (sec) |
00010000 11111111 (st3) |
8. Lowest quality qualified in QL-enabled mode |
1011 (sec/ eec1) |
1100 (smc) |
1011 (sec) |
00100010 11111111 (smc) |
9. |
1111 (dnu) |
1100 (smc) |
1111 (dnu) |
00100010 11111111 (smc) |
10. |
1111 (dnu) |
1111 (dus) |
1111 dnu |
00101000 11111111 (st4) |
11. |
1111 (dnu) |
1110 (pno) |
1111 (dnu) |
01000000 11111111 (pno) |
12. |
1111 (dnu) |
1111 (dus) |
1111 (dnu) |
00110000 11111111 (dus) |
13. |
1111 (dnu) |
1111 (dus) |
1111 (dnu) |
00110000 11111111 (dus) |
14. |
1111 (dnu) |
1111 (dus) |
1111 (dnu) |
00110000 11111111 (dus) |
15. |
1011 (sec/eec1) |
1010 (st3/eec2) |
1011 (sec) |
00010000 11111111 (st3) |