Supported Platforms
Switching LSPs Away from a Network Node
You can configure the router to switch active LSPs away from a network node using a bypass LSP enabled for an interface. This feature might be used to maintain active networks when a device needs to be replaced without interrupting traffic transiting the network. The LSPs can be either static or dynamic.
- You first need to configure either link or node protection for the traffic that needs to pass around the network device you intend to disable. To function properly, the bypass LSP must use a different logical interface than the protected LSP.
- The router then marks all OAM traffic transiting this interface in preparation for switching the traffic to an alternate path based on the OAM functionality.
To prepare the router to begin switching traffic away from a network node, configure the always-mark-connection-protection-tlv statement:
You can configure this statement at the following hierarchy levels:
- [edit protocols mpls interface interface-name]
- [edit logical-systems logical-system-name protocols mpls interface interface-name]
You then need to configure the switch-away-lsps statement to switch the traffic from the protected LSP to the bypass LSP, effectively bypassing the default downstream network device. The actual link itself is not brought down by this configuration.
To configure the router to switch traffic away from a network node, configure the switch-away-lsps statement:
You can configure this statement at the following hierarchy levels:
- [edit protocols mpls interface interface-name]
- [edit logical-systems logical-system-name protocols mpls interface interface-name]
Note the following limitations related to switching active LSPs away from a network node:
- The switch-away feature is supported on MX Series routers only.
- The switch-away feature is not supported for switching traffic from primary point-to-multipoint LSPs to bypass point-to-multipoint LSPs. If you configure the switch-away-lsps statement for a point-to-multipoint LSP, traffic is not switched to the bypass point-to-multipoint LSP.
- If you configure the switch-away feature on an interface along the path of a dynamic LSP, new dynamic LSPs cannot be established over that path. The switch-away feature prevents the make-before-break behavior of RSVP-signaled LSPs. The make-before-break behavior normally causes the router to first attempt to re-signal a dynamic LSP before tearing down the original.
