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The FRRouting Protocol Suite
https://frrouting.org/
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FRR 8.4.2 doesn't advertise APIPA 169.254/16 on L3VPN #12834

Closed networking-hub closed 1 year ago

networking-hub commented 1 year ago

Discussed in https://github.com/FRRouting/frr/discussions/12833

Originally posted by **networking-hub** February 17, 2023 Hello, I'm working on a network issue (that is quite weird actually). I have a FRR connected to a physical PE, isis/bgp/mpls/mp-bgp ... everything working fine except : - While setting a 169.254.0.20/32 (for example) on a loopback attached to a VRF, this prefix is not advertised and as consequence is not reachable by other PEs or CPE on the same VRF. I'm getting these debug messages : ``` **2023-02-17 16:07:18.214 [DEBG] zebra: [J3J81-V75NW] Route rtm_type: anycast(4) intentionally ignoring .... 2023-02-17 16:58:56.751 [DEBG] ldpd: msg[out]: address withdraw: lsr-id 10.16.168.161, address 169.254.0.20 2023-02-17 16:58:56.751 [DEBG] ldpd: msg[out]: address withdraw: lsr-id 10.16.168.161, address 169.254.0.31 ......** ``` Here is the loopback configuration : ``` **interface loopback84189 ip address 169.254.0.20/32 ip address 169.254.0.31/32 exit** ``` And of course these prefixes are not visible in bgp routing table : ``` BGP table version is 35, local router ID is 169.254.0.20, vrf id 8 Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, i internal, r RIB-failure, S Stale, R Removed Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found Network Next Hop Metric LocPrf Weight Path *> 0.0.0.0/0 10.16.168.245@0< 500 0 65001 i ... some public prefixes ... *> 169.254.0.0/31 10.16.168.245@0< 0 100 0 ? *> 169.254.0.2/31 10.16.168.158@0< 0 100 0 ? *> 169.254.0.4/31 10.16.168.163@0< 0 100 0 ? *> 169.254.0.8/31 10.16.168.179@0< 0 100 0 ? *> 169.254.0.13/32 10.16.168.116@0< 0 100 0 ? *> 169.254.0.255/32 10.16.168.218@0< 0 100 0 ? *> 172.16.0.4/30 10.16.168.179@0< 0 100 0 ? *> 192.168.252.6/32 10.16.168.179@0< 0 100 0 ? ``` When i change the ipv4 address and put (192.168.x.y/32) everything works fine... Anyone knows why is it behaving this way ? Thanks
donaldsharp commented 1 year ago

so 168.254.0.0/16 is link local space. As such it's considered private to the router it is being used on. FRR does not advertise this.