c3550 as a CE with VRF-light and BGP to PE issue

[owaisberg]

Hi Guys,

I'm trying to connect my c3550 switch as a

CE to PE with BGP. c3550 running 2 VRFs.

When I place interface facing PE into one

VRF and run BGP on it to peer with PE end

peering wouldn't work. If I remove that interface from the VRF all works just fine.

Second VRF running OSPF and connects to

other PE without any issues, so the problem is only with BGP running on second

VRF.

Activated "deb ip bgp" and "deb ip tcp transactions" on both ends (PE & CE). Can

see that PE does try to establish the

sessions on CE but CE resets (RST) that

connectionn immediately.

Please let me know if anyone seen it before.

Thanks in advance,

Oleg

[nileshrjoshi]

Hi Oleg,

Let me ask u one question ???

C3550 is the CE, U have to create a vrf on the PE router and run the MBGP session between the PE to PE. Add the interface of PE into the vrf. Pls let me know if it work or not.

[owaisberg]

c3550 is a CE that runs 2 VRFs so my

BGP peering to PE is not PE-PE but CE-PE

one within IPv4 address family of that specific VRF. Of course on the PE router

interface is part of VRF:

CE ------------- PE

VRF ----BGP---- VRF

Now, as i said, if I remove CE interface

from VRF peering to PE works fine otherwise

it is not even though there is full connectivity between two routers within that

VRF.

[swaroop.potdar]

VRF-Lite or Multi-VRF is a supported feature on 3550 (subject to IOS)

The RST can be done by one sode device when you are sending a Open message to it and it has a wrong neighbor statement configured.

This is what has been expereinced, apart from this I am not aware why its not working.

May be you can put up your config.

For Eg:

PE-1 } vrf for - ip address 10.0.0.1/30

Neighbor 10.0.0.6 remote as x

CE-1 ) vrf for - ip address 10.0.0.2/30

neighbor 10.0.0.1 remote as x.

In the above case the PE-1 will do a RST and refuse the incoming connection.

HTH-Cheers,

Swaroop

May be as usual you can upload in your config :-)

[owaisberg]

Hi HTH :)

Finally got some MPLS' shark attention.

The config is so basic it would no sense

to upload it here :) It cannot be a neighbor

statement mistake as it was checked about

100 times or so :)

Now, as I mentioned, another test I was doing is removing that interface (which faces PE)

from VRF and moving same config from address-

family ipv4 vrf XXX to ipv4 and peering comes

up instantly....put it back under VRF and

shift ipv4 config to ipv4 vrf XXX section

peering dies. But vrf connectivity maintained

though. Generic config attached.

Thanks again,

Oleg

[swaroop.potdar]

Must say your issue at hand is quite different as usual. I wont be very comfortable saying its a bug.(cos its easy way out)

Can u try using a Routed Port in place of SVI? If you have tried that already, then any observations with change in different IOS? Do update.

HTH-Cheers,

Swaroop

[owaisberg]

I'll test different interface types tonight,

as of IOS it is the latest one.

I'll keep you posted.

Thanks,

Oleg

[oettls · Accepted solution]

Hi Oleg,

do you have at least one interface in the default routing table of the multi-vrf CE ?

BGP allocates it's router-id from global address space - so you need at least one 'up/up' interface in the default routing table.

You can verfiy the BGP RID with 'show bgp all summary' ...

HTH

cheers,

Stefan

[owaisberg]

Hi Stefan,

You're absolutely right! That was the reason

and has nothing to do with the fact that CE

is on c3550. I did some testing and indeed

as long as BGP RD not specified and there

are no interfaces in global RT there is no

BGP funcionality. Fixed easily by specifying

BGP RD under BGP process.

Thanks a lot guys: Stefan and Swaroop!

I should never underestimate probability

of stupidity :)

Thanks again,

Oleg