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2007
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BGP IPv6 - Directly connected neighbor required ebgp-multihop

Lee Kendrick
Level 1
Level 1

Hi,

I have 2 x Cisco 6509-E switches running BGP for IPv6 with my ISP. Bizarrely, the BGP session establishes fine, but i do not learn any prefixes after the session is established. That is, until i add the 'neighbor x:x:x:x::y ebgp-multihop 2' command. I cant figure out why. There neighbors are directly connected.

router bgp 12345
 no bgp fast-external-fallover
 no bgp default ipv4-unicast
 no bgp enforce-first-as
 bgp log-neighbor-changes
 neighbor 2001:x:x:x::8 remote-as 54321
 neighbor 2001:x:x:x::8 ebgp-multihop 2
 neighbor 2001:x:x:x::8 password blahblahblah

 address-family ipv6
  neighbor 2001:x:x:x::8 activate
  neighbor 2001:x:x:x::8 send-community
  neighbor 2001:x:x:x::8 allowas-in
  neighbor 2001:x:x:x::8 soft-reconfiguration inbound
  neighbor 2001:x:x:x::8 prefix-list PL_INBLAH_v6 in
  neighbor 2001:x:x:x::8 prefix-list PL_OUBLAH_v6 out
  neighbor 2001:x:x:x::8 route-map RM_BLAH in

 

without ' neighbor 2001:x:x:x::8 ebgp-multihop 2' i see:

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
2001:x:x:x::8                4        54321 34343 4343 343436    0    0 00:04:32    0 <------------------------ ISSUE

 

with ' neighbor 2001:x:x:x::8 ebgp-multihop 2' i see:

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
2001:x:x:x::8                4        54321 34343 4343 343436    0    0 00:00:32    20146  <----------------- OK

 

when debugging 'debug bgp ipv6 un 2001:x:x:x::8 updates' - without ebgp-multihop cmd,  i get these messages:

911888: Dec 11 10:37:27: BGP(1): 2001:x:x:x::8 rcv UPDATE about 2405:y:y::/48 -- DENIED due to: martian MP_REACH NEXTHOP;

looking at this - i am guessing a code bug..?

 

1 Reply 1

milan.kulik
Level 10
Level 10

Hi,

 

what's the next-hop value in the prefixes denied?

 

BR,

Milan

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