Showing results for 
Search instead for 
Did you mean: 

Help with an MPLS/OSPF architecture

Help with an MPLS/OSPF architecture

New Contributor II
Hi dears,

I would like a help with the architecture displayed below. Please feel free to make any comment.

Network descriptions and requirements

- It's a metro network that have the goal to connect several locations;
- It's works like a big intranet, then there's no need the traffic isolation (VPN L3);
- Today, the network runs OSPF and have about 91 areas and 200 routers;
- The picture below shows a network summary. Each router has at least to another two routers connected;
- The customer router has two connections too;
- The backbone routers are connected to POP routers, but there are customer routers directly connected too;
- The POP routers connected to backbone routers are
part of Area 0. They are connected in another POPs and to customers too.


Reasons to implement MPLS

- Traffic Engineer
- VPWS and VPLS;
- QoS and better resource utilization;
- Picture below shows the scenario wanted:



- There're no plan to use VPN to isolate some customer traffic because one network requirement is connect all customer via L3 . Is it worth implementing BGP?

- I think that implement iBGP will increase the network complexity.

Thanks in advance for all!

Contributor II
Hi Thyago,

there is still the question about scaling to a larger number of network devices, and about traffic engineering.

Scale is usually achieved by implementing hierarchies. OSPF areas are one example, especially if those are totally stubby and address summarization can be used on the ABRs. But RSVP-TE, used for traffic engineering, operates inside one OSPF (or IS-IS) area only. RSVP-TE is quite resource intensive and thus does not scale too well.

I would suggest you take a look at the release notes of the EXOS version you use, and look for the limits regarding routes, different protocols, and so on.


Hi Erik,

I will observe it for the project! In this moment I'm mapping all the network connections and his areas. Probably the topology areas will need a change.

Thank you!

Contributor II
Hi Thyago,

if you want to use VPWS and/or VPLS with EXOS, you have to use LDP for the L2VPN (RFC 4447, RFC 4762). You would need BGP for L3VPN (BGP/MPLS IP Virtual Private Network, RFC 4364), but you write that you do not want to use it.

Thus I do not see the need for BGP for your use-case.


Hi Erik! Congratulations for your participation in community!!

I believe that I will follow this way.

Thank you so much for your time!