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Configuring MAC Flush Message Processing in CET Mode

For VPLS there is no end-to-end connectivity monitored. The access rings are independently monitored by running CFM down multiple end points (MEPs) on the working and protection paths for each of the services between the E-domain devices and the MX Series PE routers, and between the A-domain devices and the MX Series PE routers the IWF hosted by the Nokia Siemens Networks A-4100 devices. When there is a connectivity failure on the working path, the Nokia Siemens Networks Ax200 devices perform a switchover to the protection path, triggering a topology change notification (in the form of TLVs carried in CCM) to be sent on the active path.

Figure 1: CET inter-op Dual Homed Topology

Figure 1 describes the dual homed topology on MX Series PE routers connected to the A-domain. When an A-domain device triggers a switchover, it starts switching the service traffic to the new active path. This change is communicated in the HELLO protocol data units (PDUs) sent by that A-domain device on the working and protection paths. When the IWF in A4100 recieves these HELLO PDUs, it converts them to standard CCM messages and also inserts a connection protection TLV. The “Protection-in-use” field of the connection protection TLV is encoded with the currently active path, and is included in the CCM message. CCM messages are received by the MX Series PE routers through the VLAN spoke in A4100. In the above dual homed scenario, one MX Series PE router monitors the working path, and the other MX Series PE router monitors the protection path.

A MAC flush occurs when the CFM session that is monitoring the working path detects that the service traffic has moved to the protection path or when the CFM session that is monitoring the protection path detects that the service traffic has moved to the working path.

Figure 2: CET inter-op Dual Attached Topology

Figure 2 describes the dual attached topology on MX Series PE routers connected to the A-domain. The MAC flush mechanism used in this case is also the same as the one used for the A-domain in the dual homed scenario (Figure 1). However in this case both the CFM sessions are hosted by only one MX Series PE router. When Ax100 in the A-domain detects topology changes, the MX Series PE router receives the connection protection TLV in the CCM message for the working and protection paths with the value of “Protection-in-use” indicating which path is the active one. Based upon the event that is generated for the CFM session, the MX Series PE router will bring down the appropriate interface which will trigger a local MAC flush.

Configuring a Connection Protection TLV Action Profile

An action profile can be configured to perform the interface-down action based on the values of connection-protection-tlv in the received CCM packets.

The following example shows an action profile configuration with explanatory comments added: