ESMC SSM
Ethernet Synchronization Message Channel (ESMC) Synchronization Status Messages (SSM) are supported by both SDH and Ethernet networks. SDH is supported by the transport overhead channel and is unidirectional; Ethernet is defined as Organization Specific Slow Protocol (OSSP).
SSM represents the quality level of the system clocks located in the network. Background (or heartbeat) is sent once per second as keep alive. ESMC information PDU- event message is sent immediately in case the clock quality level has changed. ESMC event PDU- failure condition is declared if no message is received in 5 seconds.
| ESMC PDU Format | ||
|---|---|---|
| Octet number | Size | Field |
| 1-6 | 6 octets | Destination address = 01-80-C2-00-00-02 |
| 7-12 | 6 octets | Source address |
| 13-14 | 2 octets | Slow protocol Ethertype = 88-09 |
| 15 | 1 octet | Slow protocol subtype =0x0A |
| 16-18 | 3 octets | ITU-OUI = 00-19-A7 |
| 19-20 | 2 octets | ITU-T subtype |
| 21 | 4 bits | Version |
| 1 bit | Event flag | |
| 3 bits | Reserved | |
| 22-24 | 3 octets | Reserved |
| 25-1514 | 36-1490 octets | Data and padding (see point j) |
| Last 4 | 4 octets | Frame check sequence |
Event flag: This bit distinguishes the critical time-sensitive behavior of the ESMC event PDU from the ESMC information PDU. A value of 1 indicates an event PDU and a value of 0 indicates an information PDU.
| IEEE Assigned OUI and Slow Protocol Subtype | ||
|---|---|---|
| 8 bits | Type: 0x01 | |
| 16 bits | Length: 00-04 | |
| 4 bits | 0x0 (unused) | |
| 4 bits | SSM code | |
| QL TLV Format | ||
|---|---|---|
| Quality Level | Highest | |
| QL-PRC | Highest | |
| QL-SSU-A | | | |
| QL-SSU-B | | | |
| QL-SEC | | | |
| QL-DNU | | | |
| QL-INVx, QL-FAILED, QL-UNC, QL-NSUPP | Lowest | |
TLV: Type Length Field
QL: Quality Level
| Hierarchy of Quality Levels in Option I of Synchronization Networks | ||
|---|---|---|
| Quality Level | Order | |
| QL-PRC | Highest | |
| QL-SSU-A | | | |
| QL-SSU-B | | | |
| QL-SEC | | | |
| QL-DNU | | | |
| QL-INVx, QL-FAILED, QL-UNC, QL-NSUPP | Lowest | |
| Hierarchy of Quality Levels in Option II of Synchronization Networks | ||
|---|---|---|
| Quality Level | Order | |
| QL-PRS | Highest | |
| QL-STU | | | |
| QL-ST2 | | | |
| QL-TNC (Note) | | | |
| QL-ST3E (Note) | | | |
| QL-ST3 | | | |
| QL-SMC | | | |
| QL-ST4 | | | |
| QL-PROV (default position) | | | |
| QL-DUS | | | |
| QL-INVx, QL-FAILED, QL-UNC, QL-NSUPP | Lowest | |
| NOTE - QL-TNC and QL-ST3E are not defined for first generation synchronization networking (refer to clause 5.4.1.2) and QL-PROV was identified as QL-RES | ||
The SyncE ESMC SSM option has the following features:
- Generates “information” at a programmable interval, IPG, (default 1 sec)
- Generates “event” upon changing the QL-TLV followed by “information”
- Count message types
- Monitor and decode messages on screen
- Capture ESMC/SSM messages and output in pcap file for further off-line protocol analysis
Setup
- IPG(s): Value can be entered by clicking in the box next to it.
- SSM Code: Quality Levels
Once the parameters are set, press Start to start the test.
ESMC SSM
Results
The Results screen shows Messages, Protocol Monitor, and Capture.
Message: A list of all the SSM quality levels with the results of the QL selected in Setup next to it.
SyncE ESMC SSM Results- Message
Monitor
The Tracer shows the messages as they are sent or received. The test set stores up to 2000 messages. Tap on the desired message to view decoded message details.
SyncE ESMC SSM Results- Protocol Monitor
Message Details
Capture
Press Start to Capture Packets. The number of captured packet results is displayed.
To store these results packets, press Stop, then press Save as. Enter a name for the results file. Press Apply to save the file. The file is saved under the Files folder on the unit in pcap format. The file can be later exported to a PC and analyzed using Wireshark. Refer to File Management
SyncE ESMC SSM Results- Capture
SyncE ESMC SSM Capture Save