Oddity with BGP and v6 multipath in 5.0.1

[Nigel Kukard]

Hi guys,

Maybe I'm missing something here, but this looks a bit odd...

-- check these v6 bgp entries, they're right ... ---

xx-01-xx.xx.xx.net# show bgp ipv6 2001:nn:5600:2600::700
BGP routing table entry for 2001:nn::/32
Paths: (6 available,*best #1*, table Default-IP-Routing-Table)
  6939 20860
    2001:mm:1f1::108 from 2001:mm:1f1::108 (xx.252.112)
    (fe80::da84:66ff:feeb:6419) (*used*)
      Origin IGP, *localpref 700*, valid, external, *multipath*, *best*
      Large Community: 328112:1:710 328112:2:11 328112:2:111 328112:3:3
      AddPath ID: RX 0, TX 79328233
      Advertised to: 2c0f:mm:0:2::2 2c0f:mm:10:2::1
      Last update: Tue Oct 16 21:52:29 2018

  6939 20860
    2001:mm:6d1::165 from 2001:mm:6d1::165 (xx.252.112)
    (fe80::da84:66ff:feeb:6415) (*used*)
      Origin IGP, *localpref 700*, valid, external, *multipath*
      Large Community: 328112:1:710 328112:2:10 328112:2:101 328112:3:3
      AddPath ID: RX 0, TX 79328194
      Last update: Tue Oct 16 21:52:29 2018

  6939 20860
    2c0f:zz:0:2::2 from 2c0f:zz:0:2::2 (xx.60.1)
      Origin IGP, localpref 300, valid, internal
      Large Community: 328112:1:710 328112:2:10 328112:2:102 328112:3:3
328112:100:21
      AddPath ID: RX 0, TX 45344833
      Last update: Mon Oct 15 13:28:45 2018

  6939 20860
    2c0f:zz:10:2::1 from 2c0f:zz:10:2::1 (xx.60.1)
      Origin IGP, localpref 300, valid, internal
      Large Community: 328112:1:710 328112:2:10 328112:2:102 328112:3:3
328112:100:21
      AddPath ID: RX 0, TX 45344474
      Last update: Mon Oct 15 13:28:45 2018

[2 more entries removed]


-- from vtysh the routes look right too ... --


xx-01-xx.xx.xx.net# show ip route 2001:nn:5600:2600::700
Routing entry for 2001:nn::/32
  Known via "bgp", distance 20, metric 0, best
  Last update 10:55:53 ago
  * fe80::da84:66ff:feeb:6419, via e2p0v0
  * fe80::da84:66ff:feeb:6415, via e1p0v0


-- check these routes ... for some odd reason, the above vtysh commands
picked /32 , but thats not the entire issue --

nkukard at xx-01-xx:~# ip -6 route | grep 2001:nn
*2001:nn:3333::/48 *via 2c0f:zz:0:2::2 dev e1p1v0.400 proto 186 metric
20  pref medium
*2001:nn:3333::/48* via 2c0f:zz:10:2::1 dev e2p1v0.401 proto 186 metric
20  pref medium
*2001:nn:3333::/48 *via fe80::da84:66ff:feeb:6415 dev e1p0v0 proto 186
metric 20  pref medium
*2001:nn:3333::/48* via fe80::da84:66ff:feeb:6419 dev e2p0v0 proto 186
metric 20  pref medium
2001:nn::/32 via fe80::da84:66ff:feeb:6419 dev e2p0v0 proto 186 metric
20  pref medium
2001:nn::/32 via fe80::da84:66ff:feeb:6415 dev e1p0v0 proto 186 metric
20  pref medium


The routes are not being created as multi-path, and routes which should
not be active are added. Possibly a mismatch between the add and remove?


-N




For interest sake, here is the output of the /48 ...



-- here is the output for /48 --

xx-01-xx.xx.xx.net# show bgp ipv6 2001:nn:3333::/48    
BGP routing table entry for 2001:nn:3333::/48
Paths: (6 available, *best #2*, table Default-IP-Routing-Table)
  6939 3356
    2001:mm:1f1::108 from 2001:mm:1f1::108 (xx.252.112)
    (fe80::da84:66ff:feeb:6419) (*used*)
      Origin IGP, localpref 700, valid, external, *multipath*
      Large Community: 328112:1:710 328112:2:11 328112:2:111 328112:3:3
      AddPath ID: RX 0, TX 79816612
      Last update: Tue Oct 16 22:07:13 2018

  6939 3356
    2001:mm:6d1::165 from 2001:mm:6d1::165 (xx.252.112)
    (fe80::da84:66ff:feeb:6415) (*used*)
      Origin IGP, localpref 700, valid, external, *multipath*, *best*
      Large Community: 328112:1:710 328112:2:10 328112:2:101 328112:3:3
      AddPath ID: RX 0, TX 79816391
      Advertised to: 2c0f:f3c8:0:2::2 2c0f:f3c8:10:2::1
      Last update: Tue Oct 16 22:07:13 2018

  6939 3356
    2c0f:zz:10:2::1 from 2c0f:zz:10:2::1 (xx.60.1)
      Origin IGP, localpref 300, valid, internal
      Large Community: 328112:1:710 328112:2:11 328112:2:112 328112:3:3
328112:100:21
      AddPath ID: RX 0, TX 5886849
      Last update: Mon Oct 15 13:28:50 2018

  37271 3356
    2c0f:mm:200:2:2::22 from 2c0f:mm:200:2:2::22 (xx.189.115)
    (fe80::b2aa:77ff:fe32:40bf) (used)
      Origin IGP, metric 401, localpref 50, valid, external
      Community: 3356:2 3356:22 3356:123 3356:500 3356:601 3356:2064
37271:5002 37271:5100 37271:5101
      Large Community: 328112:1:710 328112:3:4 328112:3:403 328112:3:4031
      AddPath ID: RX 0, TX 549813
      Last update: Thu Sep 20 04:13:21 2018

  6939 3356
    2c0f:zz:0:2::2 from 2c0f:zz:0:2::2 (xx.60.1)
      Origin IGP, localpref 300, valid, internal
      Large Community: 328112:1:710 328112:2:11 328112:2:112 328112:3:3
328112:100:21
      AddPath ID: RX 0, TX 172320
      Last update: Mon Oct 15 13:28:50 2018

  37100 37100 3356
    2c0f:mm:c:2::b5 from 2c0f:mm:c:2::b5 (xx.0.151)
    (fe80::86b5:9c07:e2fd:cc80) (used)
      Origin IGP, localpref 50, valid, external
      Community: 37100:1 37100:13
      Large Community: 328112:1:710 328112:3:4 328112:3:401 328112:3:4011
      AddPath ID: RX 0, TX 14726
      Last update: Tue Sep 18 22:20:34 2018


-- lets see what the routes look like from vtysh ... looks good ... ---

xx-01-xx.xx.xx.net# show ip route 2001:nn:3333::/48
Routing entry for 2001:nn:3333::/48
  Known via "bgp", distance 20, metric 0, best
  Last update 10:51:35 ago
  * fe80::da84:66ff:feeb:6415, via e1p0v0
  * fe80::da84:66ff:feeb:6419, via e2p0v0








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