SR OAM Tools
Last updated
Last updated
Load top2.sdn.transport.init.cfg in topology1.
Enable MPLS OAM everywhere.
MPLS ping and traceroute can be used with SR-MPLS. MPLS ping and traceroute are used to verify an MPLS LSP, as basic ping and traceroute can fallback to IP forwarding.
When using SR-MPLS, the router will automatically use the SR Prefix SID FEC type with basic mpls ping and mpls traceroute even though you do not specify it.
The “more proper” way to do this from the CLI would be to use ping sr-mpls and specifying the target FEC. This produces the exact same LSP Ping as seen above. (FEC type is Prefix SID from ISIS).
If you use ping sr-mpls without the fec-type, it will be a generic fec type instead.
ping sr-mpls gives us the ability to ping using an SR policy as well. We must specify the endpoint of the policy when using this.
Finally, we can use a nil-fec type in order to program an arbitrary stack of labels. This can be done with either ping sr-mpls or ping mpls, there is no difference. You must specify the output interface and nexthop.
Just like with MPLS Ping, MPLS traceroute can be used with either traceroute mpls or traceroute sr-mpls. When traceroute mpls is used, the FEC type is automatically the Prefix SID with the IGP protocol. When using traceroute sr-mpls, the FEC type is generic by default, and you can specify IGP or BGP.
MPLS traceroute simply uses LSP echo requests but with a downstream mapping TLV to allow each hop to verify the correct mapping information upon ingress. (The first hop sends its downstream neighbor’s IP address and label value. The second hop verify this is correct and return its own downstream mapping to be used for the next probe).
MPLS traceroute can be multipath aware. Use the following traceroute to see all ECMP paths:
Just as with the LSP Ping, the benefit of traceroute sr-mpls is the ability to trace and SR policy.
We can also use a nil-fec type to trace using any arbitrary stack of labels.
