[c-nsp] CEF-based per-packet load-sharing under MPLS VPN

[Everton da Silva Marques]

Oliver Boehmer (oboehmer) wrote:
> 
> > #sh ip bgp vpnv4 vrf 5500000001-98 10.14.62.0
> > BGP routing table entry for 15180:4829:10.14.62.0/32, version 358152
> > Paths: (1 available, best #1, table 5500000001-98)
> >   Not advertised to any peer
> >   Local, imported path from 15180:4824:10.14.62.0/32
> >     0.0.0.0 (via 5500000001-99) from 0.0.0.0 (200.202.113.165)
> >       Origin incomplete, metric 0, localpref 100, weight 32768,
> >       valid, external, best Extended Community: RT:15180:1
> >         RT:15180:4701 RT:15180:5001 RT:15180:5009
> 
> Hmm, the next-hop looks strange. I'd expect to see 1.1.1.1. Did you
> import both prefixes (10.14.62.0 & 1.1.1.1) in the VRF? How does your
> vrf config look like (or please send full config unicast)?

We redistribute static routes from vrf 5500000001-99
into BGP with RT 15180:5001, then import them in
5500000001-98. This is the relevant config:

ip vrf 5500000001-98
 rd 15180:4829
 route-target import 15180:5001
!
ip vrf 5500000001-99
 rd 15180:4824
 import map SPTrans-COT_inbound
 route-target export 15180:1
 route-target export 15180:5009
 route-target export 15180:4701
 route-target export 15180:5001
 route-target import 15180:2
 route-target import 15180:4000
 route-target import 15180:4001
 route-target import 15180:5000
 route-target import 15180:5001
!

interface Serial6/0/0:0
 ip vrf forwarding 5500000001-99
 ip address 10.4.62.1 255.255.255.252

interface Serial6/0/1:0
 ip vrf forwarding 5500000001-99
 ip address 10.6.3.129 255.255.255.252

router bgp 15180
 ! (...)
 address-family ipv4 vrf 5500000001-99
 redistribute connected
 redistribute static
 maximum-paths 2
 no auto-summary
 no synchronization
 exit-address-family
 !
 address-family ipv4 vrf 5500000001-98
 redistribute connected
 redistribute static
 no auto-summary
 no synchronization
 exit-address-family
!

> definitly not, you see a null adjacency here,
> possibly caused by a Null0 static default
> route in vrf 5500000001-98?

As far as I can tell, the null adjacency
should not be there:

#sh run | i ip route vrf 5500000001-98
#
#sh run | i ip route vrf 5500000001-99
ip route vrf 5500000001-99 1.1.1.1 255.255.255.255 Serial6/0/0:0 10.4.62.2
ip route vrf 5500000001-99 1.1.1.1 255.255.255.255 Serial6/0/1:0 10.6.3.130
ip route vrf 5500000001-99 10.14.62.0 255.255.255.255 1.1.1.1

#sh ip route vrf 5500000001-98

Routing Table: 5500000001-98
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR

Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
B       1.1.1.1 [20/0] via 10.6.3.130 (5500000001-99), 01:20:43, Serial6/0/1:0
     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks
B       10.4.62.0/30 is directly connected, 01:44:09, Serial6/0/0:0
B       10.6.3.136/30 [200/0] via 200.202.113.160, 01:36:12
B       10.6.3.128/30 is directly connected, 01:36:27, Serial6/0/1:0
B       10.26.3.128/25 [200/0] via 200.202.113.160, 01:36:12
B       10.16.3.128/32 [200/0] via 200.202.113.160, 01:36:12

> consider eBGP, then it will work much cleaner.. root-problem with two
> equal cost static routes is that you will only see one BGP path after
> redistribution. And since BGP is used to leak routes between VRFs, you
> loose the information. With eBGP, you can use e/iBGP multipath and
> announce all available paths..

Will do.

Thanks again.

Regards,
Everton