Active / Backup Lastmile Connection

[Abid Abdul Latif]

Dear All,

We have MPLS core on which we provide l3 mpls vpn service.

There is a scenario that customer required dual last mile on difference locations acting as active and backup.

We provide lastmile via access network partner which extends the last miles to our PE over l2 (vlan) so on our PE what we get  two vlan coming on two different physical interfaces. And then we establish BGP connection to our CE on customer end.

So from last mile provide both lastmiles are available and active all the time. But on the core we have to make sure that only one lastmile is used and second lastmile is only used when the primary link goes down.

Currently we do it by connecting both ce to each other and running bgp between them. To make sure that we control the primary path.

Is this is the only way or there can be some other option for this setup.

Thanks

[Mohamed Sobair]

Hi,

In Such Situation, the provider doesnt need to control outbound direction and incoming connection, this has to be done on the CE side since its dual homing to a single provider.

The Provier would still use Only One path to reach the Network behind your CEs (If you are advertising the Similar Network on both CEs to the Provider). However, If you need to control it from the provider side its also possible.

I think its best for you to control Outbound and Inbound direction using BGP Path Attributes.

HTH

Mohamed

[Abid Abdul Latif]

Thanks for the reply. The advertisement of the networks are managed by the customer.

I agree that we can control this via bgp attributes what if the customer only advertise the network via backup path in that case customer can use backup link as well. To avoid this we are using bgp between the ce's.My concern is, is there any better or simple way to do this.

Regards

[Mohamed Sobair]

Hi,

No, this is the best approach, you are connecting your Edge router through IBGP, and advertises Networks from both CEs towards the provider.

Actually the provide need not to do any thing at thier site, Only the CEs control this and this is the normal approach.

May I ask you what is exactly your concern regarding this setup?

Regards,

Mohamed

[Abid Abdul Latif]

My concern is what is the customer on two different locations and there is no interconnection between the ce's then how can we enforce the customer to not to use the backup link when primary link is active.

keeping in mind that customer has control to advertise networks whereever they want.

Regards

[Mohamed Sobair]

Hi,

It is important to have a link between your CEs , if you intened to have Active / Standby setup, or else a failure on one link cant be detected by the other CE and both CEs will be forwarding.

I can say, there is no way to have primary.backup Scenario, unless you have a backdoor link between your CEs.

Regards,

Mohamed