ExtremeXOS provides Connectivity Fault Management (CFM) support within EAPS protocol.
CFM reports fault connectivity failures to EAPS (Extreme Automatic Protection Switching), and EAPS communicates with the CFM process to set up point-to-point DOWN MEPs (Management Endpoints) to monitor link connectivity. The CFM module notifies EAPS of any link-connectivity issues, and triggers EAPS to take necessary action.
802.1ag CFM supports link monitoring. It does this by sending out PDUs at designated transmit intervals. If the CFM fails to receive PDUs, it assumes the link is out of service, and notifies its clients. In this instance, EAPS acts as a CFM client.
First, you will create a down MEP within the CFM CLI. Configure the CLI to create a MEP group that associates this down MEP with a remote MEP (RMEP). There is a 1:1 relationship between a port and the down MEP, and as such, each MEP group is tied to a single port. Using the EAPS CLI, you can add the MEP groups you wish to monitor. For each MEP group added to EAPS, EAPS will receive UP/DOWN notifications from CFM when CFM detects a MEP state change for that group. Each MEP group corresponds to an EAPS ring port. Notifications from those MEP groups that are inadvertently added—that do not correspond to an EAPS ring port—are ignored in EAPS.
The CFM configuration is independent of EAPS, and MEPs and MEP groups may use different VLANs other than the EAPS control VLAN (Virtual LAN) to monitor links.
When EAPS receives a CFM notification that the link failed, EAPS blocks that port on all of the EAPS control VLANs. This prevents EAPS control PDUs from being hardware forwarded on the link, in case the link is still up. Any EAPS PDUs that are received on a CFM failed port are dropped in EAPS. It is generally recommended to have the CCM interval as short as possible to detect link failures faster, which improves convergence time.
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