Discussion:
[c-nsp] Cisco 7200's not importing prefixes when RT of ASN:VRF_ID used
Stephen Fulton
2018-08-16 13:42:15 UTC
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Hi all,

I am having difficulty with some older Cisco 7200's within a production
MPLS network. The others hosts are IOS-XE or IOS-XR based and there are
no issues with those. The problem devices, plural, are 7206's with
several different versions of IOS, so I do not believe it is a bug but
likely a configuration issue.

The issue I am facing is that route-targets formatted as ASN:VRF_ID are
not being accepted by the 7200's. Route-targets formatted as IP:VRF_ID
are. Example VRF configs:

! Non-working configuration on a 7200
vrf definition VRF999
rd 1.0.0.1:999
address-family ipv4
route-target export 23456:999
route-target import 23456:999

! Working configuration on a 7200
vrf definition VRF999
rd 1.0.0.1:999
address-family ipv4
route-target export 1.0.0.1:999
route-target import 1.0.0.2:999
route-target import 1.0.0.3:999
(etc)

All other participating devices will see prefixes exported from the
7200's when ASN:VRF_ID is used, but the 7200 will not see any prefixes
which should be imported when using ASN:VRF_ID.

When IP:VRF_ID is used, all is well, however I cannot utilize that
format without significant changes across the network, which is a very
undesirable option. I could potentially use route-target rewrite but I
want to avoid that if possible as well.

What am I missing? It has been almost a decade since I last ran into
something like this, which is several networks ago and for the life of
me I cannot recall and my Google-fu is failing.

Thanks,

Stephen

PS: I do have a BGP configuration for the VRF on the 7200's.. an example
below.

router bgp 23456
address-family vpnv4 uni
neighbor 1.0.0.2 send-community both
neighbor 1.0.0.3 send-community both
(etc etc)
address-family ipv4 vrf VRF999
redistribute connected
redistribute static
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James Bensley
2018-08-20 20:54:33 UTC
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Hi Stephen,

Do you see the routes being advertised from the iBGP neighoubrs?
show bgp vpnv4 uni vrf all neighbor 7200.ibgp.ip.addr adv | beg :999

Do you see the routes being received in the VPNv4 table on the 7200?
show bgp vpnv4 uni vrf all neigh ibgp.peer.ip.addr routes | beg :999
show bgp vpnv4 uni rd 1.0.0.1:999

What do you see if you use soft-reconfiguration inbound?

What about if you mix ASN:VPN_ID and IP:VPN_ID RTs on the VRF
definition on the 7200, do you still only see those with an IP:VPN_ID
RT?

Cheers,
James.
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