Connecting PE to PE to P carrier Class Architecture

Answered Question
Jun 6th, 2008

Hi,

I am trying to deploy a carriers carrier MPLS build as an interim solution to a customer.

The CE Router 3845 is to be converted to a PE and connected to the NE40 Huawei PE router in order to peer with an NE 40 Huawei P node using loopback addresses.Is this achievable?

If so what are the draw backs and if not what would be the alternative?

I have this problem too.
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Correct Answer by Harold Ritter about 8 years 6 months ago

Oladeji,

If the 3845 is used as a PE then you need to include in the BGP mesh that is currently deployed in your core (or BGP route reflection). This 3845 will become part of your core just as any of the other PEs (including the NE40).

VRF-lite is not applicable in this case.

Regards,

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Harold Ritter Sat, 06/07/2008 - 04:48

Oladeji,

It is certainly possible to turn the 3845 into a PE and therefore extend the MPLS core to this box. Obviously, it might not scale as well as a bigger router if your core grows to a larger number of routers.

What are the requirements for turning the 3845 into a PE? Is it just to extend the multiple VRF to the CE? If so, you could probably just run VRF-lite (Also known as multi-vrf), which fullfils the requirement without having to grow your core.

Regards,

o.ilesanmi Sat, 06/07/2008 - 08:23

Thanks.

The 3845 router is dedicated for a specific customer with its own branches as CEs to the 3845 PEs and managed by the Service Provider.

Obviously, the 3845 PE connects to the NE40 PEs as an extension of the MPLS core but how will the configuration of the BGP session and the vrf-lite functionality be applied here?

Do you have any documentations that can assist me with this?

Harold Ritter Sat, 06/07/2008 - 08:59

Oladeji,

The fact that the branches all connect to the same router doesn't necessarily make it a PE. If the different branches need to be isolated from one another then the 3845 could just run vrf-lite and dot1q can be used to extend each VRF from the 3845 to the NE40 PE.

You could then run a BGP session from the 3845 to the NE40 and another one from the 3845 to the branch router or maybe just static routes or a mix depending on the redundancy requirements.

Regards,

o.ilesanmi Sat, 06/07/2008 - 09:52

hritter,

The different branches will represent one vrf for the customer and should aggregate the routes from the branches propagated by bgp to the NE 40 PEs so the second option works for me.

The attachment highlights the customers requirements which your bgp suggestion addresses.

Let me know if there is still anything to watch out for.Its a live network on the core and any documentations will help as well.

Regards,

Harold Ritter Sat, 06/07/2008 - 14:02

Oladeji,

From what I can see, the 3845 doesn't need to be a PE and doesn't need to use VRF-lite either. It will just act has a CE and will have a connection to one or more PEs and multiple connections to the branch routers.

Was there any reasons you wanted to make the 3845 a PE.

Regards,

o.ilesanmi Sat, 06/07/2008 - 22:14

Yes!!

The SP had committed to this and a signed contract had been reached between the SP and the customer with over 200 branches.Management of the 3845 as a PE will be the responsibility of the SP.Convincing the customer now to make it a CE is a no GO.

The customer here is integrating his infrastructure into 2 similar SPs (MPLS) the second of which I am working for in order to guarantee availability/resilience for the customers network due to network failure re one link of an SP fails at the branch, traffic is routed through the second SPs link. Both using BGP but different SPs.

Will this PE to PE to P provide the stop gap needed to move this forward conclusively and how? The business here is in millions of dollars.

Regards,

Harold Ritter Sun, 06/08/2008 - 06:26

Oladeji,

So if I understand you well, the 3845 will carry only one VRF, right? So it doesnt bring any advantage to make it a PE. It looks like the 3845 will be a PE for commercial reasons rather than for technical reasons.

It will certainly work but this is just adding additional devices to your mpls core (i.e. additional routers in your core IGP, additional BGP routers connecting to your BGP RRs or BGP mesh). How many 3845 are you planning to handle the 200 branches?

In this context the NE40 will just become a P router for the 3845.

Let me know if you have any specific questions.

Regards,

o.ilesanmi Sun, 06/08/2008 - 08:40

hritter,

Yes it will only carry one vrf and this is commercially inclined not technical.There are 7 3845 routers as PEs for the 200 branches.

Good to know it will work but my specific question is how is the bgp config configured? Is it from PE to N40 PE? or will it be PE to P but using the NE40 PE as a transit medium for the bgp session connection?

Will the vrf-lite functionality still be used?

Regards,

Correct Answer
Harold Ritter Sun, 06/08/2008 - 12:09

Oladeji,

If the 3845 is used as a PE then you need to include in the BGP mesh that is currently deployed in your core (or BGP route reflection). This 3845 will become part of your core just as any of the other PEs (including the NE40).

VRF-lite is not applicable in this case.

Regards,

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