Continuity Check Messages - Dell S4820T Configuration Manual

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Continuity Check Messages

Continuity check messages (CCM) are periodic hellos.

Continuity check messages:

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

CCMs 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 process the CCM messages the MEPs originate and construct a MIP CCM database.

MEPs and MIPs filter CCMs from higher and lower domain levels as described in the following table.

Table 6. Continuity Check Message Processing

Less than my level

Bridge-relay side or

Bridge-relay side

Greater than my

Bridge-relay side or

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:

Loss of three consecutive CCMs from any of the remote MEP, which indicates a network failure.

Reception of a CCM with an incorrect CCM transmission interval, which indicates a configuration

Reception of a CCM with an incorrect MEP ID or MAID, which indicates a configuration or cross-

connect error. This error could happen when different VLANs are cross-connected due to a

configuration error.

Reception of a CCM with an MD level lower than the receiving MEP, which indicates a configuration

or cross-connect error.

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

you encounter any of the these errors.

UP-MEP Action

Down-MEP Action MIP Action

Add to MIP-DB and

add to MIP-DB and