Continuity Check Messages - Dell Force10 C150 Configuration Manual

Continuity Check Messages

Continuity Check Messages (CCM) are periodic hellos used to:
• discover MEPs and MIPs within a maintenance domain
• detect loss of connectivity between MEPs
• detect misconfiguration, such as VLAN ID mismatch between MEPs
• to detect unauthorized MEPs in a maintenance domain
Continuity Check Messages (CCM) are multicast Ethernet frames sent at regular intervals from each MEP.
They have a destination address based on the MD level (01:80:C2:00:00:3X where X is the MD level of
the transmitting MEP from 0 to 7). All MEPs must listen to these multicast MAC addresses and process
these messages. MIPs may optionally processes the CCM messages originated by MEPs and construct a
MIP CCM database.
MEPs and MIPs filter CCMs from higher and lower domain levels as described in
Table 5-1. Continuity Check Message Processing
Frames at
Less than my level
My level
Greater than my level
All the remote MEPs in the maintenance domain are defined on each MEP. Each MEP then expects a
periodic CCM from the configured list of MEPs. A connectivity failure is then defined as:
1. Loss of 3 consecutive CCMs from any of the remote MEP, which indicates a network failure
2. Reception of a CCM with an incorrect CCM transmission interval, which indicates a configuration
error.
3. Reception of CCM with an incorrect MEP ID or MAID, which indicates a configuration or
cross-connect error. This could happen when different VLANs are cross-connected due to a
configuration error.
4. Reception of a CCM with an MD level lower than that of the receiving MEP, which indicates a
configuration or cross-connect error.
5. Reception of a CCM containing a port status/interface status TLV, which indicates a failed bridge or
aggregated port.
The Continuity Check protocol sends fault notifications (Syslogs, and SNMP traps if enabled) whenever
any of the above errors are encountered.
Frames from
Bridge-relay side or Wire side
Bridge-relay side
Wire side
Bridge-relay side or Wire side
UP-MEP Action Down-MEP Action MIP Action
Drop Drop
Consume Drop
Drop Consume
Forward Forward
Table 5-1.
Drop
Add to MIP-DB
and forward
Forward
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