vpnv4 to rip redistribution, route not showing in rip route table

I noticed this situation whilst working through the INE Inter-AS with back-to-back vrf topology. This back-to-back or Inter-AS link is between 2 PE routers.

RIPv2 routes from the customer CE's are injected into VPN, carried across to the back to back link where they are redistibuted back into RIPv2. The back to back peer router can see these routes and full connectivity is available between customer CE routers connected to either VPN. So far no problem, all is working as expected.

But, during the config build stage I noticed that the PE connected to the Inter-AS link shows the injected CE routes as BGP routes, not RIP routes. I see this in the output of show ip route vrf VPN_A.

The routes are redistributed from MP-BGP into RipV2 on this PE.

I would have expected to see these showing up as RIP routes, as RIP has a better AD than BGP, why don't they show as RIP routes?

If I check the RIP database for the vrf on this PE they do show as RIP entries and are shown as redistributed routes.

Is there a reason for this behaviour?

 

For example one of the CE loopbacks is 9.9.9.9/32

On the Inter-AS PE in the same VPN as the CE is connected to

show ip route vrf VPN_A     

9.0.0.0/32 is subnetted, 1 subnets
B        9.9.9.9 [200/1] via 4.4.4.4, 00:15:04

 sh ip rip database vrf VPN_A
9.0.0.0/8    auto-summary
9.9.9.9/32    redistributed

Peer PE across Inter-AS link

show ip route vrf VPN_A

R        9.0.0.0/8 [120/2] via 10.1.13.1, 00:00:11, Ethernet1/0.10
R        9.9.9.9/32 [120/2] via 10.1.13.1, 00:00:11, Ethernet1/0.10

As can be seen the route is passed correctly as a RIP route to the peer VPN, so why dosent it show in the egress PE's route table as a rip route?

Andy

 

 

Comments



  • Does the ASBR learn the 9.9.9.9/32 from VPNv4 BGP from the originating PE router? then in this case this would correct vs the Inter-AS ASBR who learns this as Option A across the ASBR transit link running RIPv2 (same would be the case if you we're running Static/OSPF or EIGRP)

    Only when running eBGP across the Option-A link would it be BGP learned

    The opposite would be the same if learning routes from the originating PE router on the other ASBR

    Official Cisco wording for the "Inter-AS PE's" is ASBR

    On Tue, Sep 30, 2014 at 3:07 PM, andy321 <[email protected]> wrote:

    I noticed this situation whilst working through the INE Inter-AS with back-to-back vrf topology. This back-to-back or Inter-AS link is between 2 PE routers.

    RIPv2 routes from the customer CE's are injected into VPN, carried across to the back to back link where they are redistibuted back into RIPv2. The back to back peer router can see these routes and full connectivity is available between customer CE routers connected to either VPN. So far no problem, all is working as expected.

    But, during the config build stage I noticed that the PE connected to the Inter-AS link shows the injected CE routes as BGP routes, not RIP routes. I see this in the output of show ip route vrf VPN_A.

    The routes are redistributed from MP-BGP into RipV2 on this PE.

    I would have expected to see these showing up as RIP routes, as RIP has a better AD than BGP, why don't they show as RIP routes?

    If I check the RIP database for the vrf on this PE they do show as RIP entries and are shown as redistributed routes.

    Is there a reason for this behaviour?

     

    For example one of the CE loopbacks is 9.9.9.9/32

    On the Inter-AS PE in the same VPN as the CE is connected to

    show ip route vrf VPN_A     

    9.0.0.0/32 is subnetted, 1 subnets
    B        9.9.9.9 [200/1] via 4.4.4.4, 00:15:04

     sh ip rip database vrf VPN_A
    9.0.0.0/8    auto-summary
    9.9.9.9/32    redistributed

    Peer PE across Inter-AS link

    show ip route vrf VPN_A

    R        9.0.0.0/8 [120/2] via 10.1.13.1, 00:00:11, Ethernet1/0.10
    R        9.9.9.9/32 [120/2] via 10.1.13.1, 00:00:11, Ethernet1/0.10

    As can be seen the route is passed correctly as a RIP route to the peer VPN, so why dosent it show in the egress PE's route table as a rip route?

    Andy

     

     




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