BGP Labled Unicast address family

[mrityunjay singh]

Hello Connections,

I have simple topology as below.I am trying to accomplish the transport from R1 loopback to R4 loopback using BGP labled unicast.

R1-----R2----ASBR1----ASBR2---R3----R4

R1--R2--ASBR1 --ospf 1 running

ASBR2--R3--R4---ospf 2 running

R2 and R3 are RR running ipv4 labeled unicast with its client R1/ASBR1 & ASBR2/R4 respectively.

R1-R2-ASBR1--running BGP 65535

ASBR2-R3-R4 --running BGP 65536

Mpls ldp is not used anywhere , also no vpnv4 address family as only need to test the transport  from R1 loopback to R4 loopback using labeled.

How the labeled based transport between R1 and R4 can be achieved in this scenario.

Thanks,

Mrityunjay

[Harold Ritter]

Hi Mrityunjay,

You would normally need to run InterAS option C (BGP IPv4 + Label) between the two ASBRs and then run LDP (or RSVP or Segment Routing(SR)) in each domain. BGP IPv4 + label would signal the end to end LSP (between R1 and R4) and LDP (or RSVP or SR) would signal the LSP from the local PE to the ASBR.

Regards,

[mrityunjay singh]

Hello Harold,

Lets say if we remove the IGP totally and create end to end BGP LU using physical interface will it work?

Why we need LDP if BGP is capable of generating label for transport.

Thanks,

Mrityunjay

[Harold Ritter]

Yes, this would work. Bear in mind that in this scenario, each transit router in each AS (R2 and R3) would act as an inline route reflector.

Regards,

[mrityunjay singh]

Hello Harold,

Thanks for the update.

I tested the solution on IOS using ebgp peering between the node and the end to end labeled tranport is working fine.

However for IOS-XR the solution do not worked , though I used /32 static routes on all the router towards the next hop.

Thanks,

Mrityunjay

[Harold Ritter]

Hi Mrityunjay,

In addition to the static route technique that is used in XR for InterAS eBGP, you will also need to use the following configuration to enable MPLS on the iBGP interfaces.

router bgp xxxx

 mpls activate interface <iBGP interface 1>

 mpls activate interface <iBGP interface 2>

...

Regards,

[Sayed Nada]

in IOS-XR you must enable MPLS LDP even if LDP is not used, doing so that will allow the software to generate labels. If you do show IP cef, you will see the next hop is unresolved. as soon as you add the command MPLS LDP you see the next hop showing label. Test it and let me know.

[Harold Ritter]

Hi Mrityunjay,

Have you been able to try the solution I provided?

Regards,