Autoroute vs Forwarding Adjacency use cases

[nwekechampion]

Hey guys,

Could anyone explain the difference between autoroute and forwarding adjacency, please? and what would be the use case for both?

[Torbjørn · Accepted solution]

Autoroute is used to dynamically add a TE tunnel as a link to the local SPF tree without advertising it in the IGP - allowing the TE tunnel to be the

next hop

in your local routing table. Forwarding adjacency allows you to advertise the TE tunnel as a connected link in your IGP. You want to advertise TE tunnels as links in your IGP is useful whenever your need to convey the path through the TE tunnel to routers which don't terminate the TE tunnel itself.

[M02@rt37 · Accepted solution]

Hello @nwekechampion,

Forwarding adjacencies are the basic building blocks for forwarding MPLS traffic in an MPLS network. Autoroute, on the other hand, is a feature that enhances MPLS traffic engineering by automatically establishing forwarding adjacencies for specific routes to optimize the network's performance.

The use case for each depends on the network's requirements: basic MPLS forwarding can be achieved with forwarding adjacencies, while autoroute is useful for complex traffic engineering scenarios.

Furthermore, autoroute keeps the TE tunnel local to the router using it, allowing it to be a

next hop

in the routing table without advertising it to the entire network. On the other hand, forwarding adjacency includes the TE tunnel in the IGP so that routers beyond the local one are aware of its existence and can use it in their routing decisions.

[nwekechampion]

Thanks guys

Very helpful

[M02@rt37]

You're so welcome @nwekechampion