Hi All, Like my other post about Egress Protection on Juniper, is anyone using what Juniper call "Longest Match for LDP" - their implementation of RFC5283 LDP Extension for Inter-Area Label Switched Paths (LSPs) ?
The Juniper documentation is available here: https://www.juniper.net/documentation/en_US/junos/topics/concept/longest-match-support-for-ldp-overview.html https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/configuring-longest-match-ldp.html As before, as far as I can tell only Juniper have implemented this: - Is anyone use this? - Are you using it in a mixed vendor network? - What is your use case for using it? I'm looking at IGP/MPLS scaling issues where some smaller access layer boxes that run MPLS (e.g. Cisco ME3600X, ASR920 etc.) and have limited TCAM. We do see TCAM exhaustion issues with these boxes however the biggest culprit of this is Inter-AS MPLS Option B connections. This is because Inter-AS OptB double allocates labels, which means label TCAM can run out before we run out of IP v4/v6 TCAM due to n*2 growth of labels vs prefixes. I'm struggling to see the use case for the feature linked above that has been implemented by Juniper. When running LDP the label space TCAM usage increments pretty much linearly with IP prefix TCAM space usage. If you're running the BGP VPNv4/VPNv6 address family and per-prefix labeling (the default on Cisco IOS/IOS-XE) then again label TCAM usage increases pretty much linearly with IP prefix TCAM usage. If you're using per-vrf/per-table labels or per-ce labels then label TCAM usage increases in a logarithmic fashion in relation to IP Prefix usage, and in this scenario we run out of IP prefix TCAM long before we run out of label TCAM. My point here is that label TCAM runs out because of BGP/RSVP/SR usage, not because of LDP usage. So who is using this feature/RFC on low end MPLS access boxes (QFX5100 or ACX5048 etc.)? How is it helping you? Who's running out of MPLS TCAM space (on a Juniper device) before they run out of IP prefix space when using LDP (and not RSVP/SR/BGP)? Cheers, James. _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
