[c-nsp] IPv6, neighbor detection, BGP and my nerves...

[Elmar K. Bins]

Hello everybody,

here's the setup:

Router model is 7301+PA-2FE-TX with IOS 12.3(14)T3. For those
who shout "upgrade!" already - same problem with 12.4s.

Router is connected to HKIX via FastEthernet1/1.

No problems whatsoever in IPv4, but here's what I have in IPv6:

  1. IPv6 BGP saves routes with a prefix source of <official
     IPv6 address>, but stores the next hop out of FE80::/8.

[ipv6 bgp]
BGP routing table entry for 2001:4F8::/32, version 42465
...
  6939 1280
    2001:7FA:0:1::CA28:A19E (FE80::212:F2FF:FE9C:2150) from 2001:7FA:0:1::CA28:A19E (216.218.252.180)
      Origin IGP, localpref 100, valid, external, best

[ipv6 route]
B   2001:4F8::/32 [20/0]
     via FE80::212:F2FF:FE9C:2150, FastEthernet1/1


  2. The trouble is that the router does not "see" some of the
     FE80::/8 addresses most of the time, meaning that IPv6 nd
     does not resolve (router gets no answer) and leaves "INCMP"
     entries in the neighbor table.

     At other times (quite rarely), the FE80:: address is reachable
     and IPv6 ND resolves.
    
     The official IP address of the partner is always "visible".

[ipv6 nei]

2001:7FA:0:1::CA28:A19E                     0 0012.f29c.2150  REACH Fa1/1
FE80::212:F2FF:FE9C:2150                    0 -               INCMP Fa1/1


Clearing the ipv6 neighbor table does not help...

Can anyone help me with these following questions:

  Towards 1. above - can I keep the FE80 addresses out of the equation
  entirely and have BGP save the neighbor address as the next hop?

  Towards 2. above - has anyone seen same behaviour and/or have a
  - workaround
  - lead to a bug id?


Any help is much appreciated...

Yours,
	Elmar.