Hey everyone, delving into the realm of multihop BFD packet protection. You know, those BFD packets travel through UDP/IP with their unique encapsulation. Now, let's say we've got a segment routing-enabled network with FRR enabled, and the FIB is populated by LFA and TI-LFA paths. So, each next-hop has a primary and backup path to safeguard link and node integrity. All PE routers maintain IBGP sessions with aggregate routers positioned between segment routing and the core network. For swift convergence, we need to secure IBGP sessions with multi-hop BFD.
Here's the big question I'm tossing to the community: Does Cisco IOS XR provide the support to keep those multihop BFD sessions alive if our primary path goes down or if there are changes in the network? According to ASR9K, multihop BFD sessions keep rolling as long as there's a clear path to the BFD peer. They only take a break if the line card hosting the party decides to reload.
Are BFD packets always encapsulated using SID-Label to leverage the forwarding plane FRR mechanism? Some vendors opt not to encapsulate multi-hop BFD using MPLS Label directly. They have a few tricks, like configuring a static route to the NH and using an indirect next-hop resolution to an MPLS LSP path.
