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VRF-lite design in a little ISP scenario


we are a little regional ISP that provides Internet transit services to local governmental organizations. We have two customers’ types each one should use a different Internet Carrier: Carrier A and d Carrier B. So A-customers use only the Carrier A to access to Internet a B-customers Carrier-B. We have eBGP and two connections (active-backup) for each carrier. Our network is very simple with four POPs in a ring topology. Besides it’s important interconnect all the organizations and that traffic between them should be routed inside the network.

So far we have used router-map’s and only the global routing table because each pop belong to a customer type. Now we are designed a new network and we’ll have both customer’s types in all POP’s.

We think that VRF-Lite could be useful in our scenario. We need insolated customers because the path to Internet will be different for each customer. The IGP will be OSPF, two process each one in a different VRF. The default route will be inyected by the OSPF process in each VRF based on default route received from the carrier BGP peer’s.

To import/export the routers between VRF we have several options:

  • Use Multiprotocol BGP in one POP to import/export the routes between VRF’s. In the M-BGP we redistributed routes learning by OSPF processes from remote POPS. After, the routes learning by the M-BGP’s import/export process will be redistributed in the OSPF’s processes to announce the remote POP’s that could reach inter-VRF organizations. Then the traffic between VRF’s always will be interchanged in one POP that will be a single failure point then.
  • Use Multiprotocol BGP in all the POP’s import/export only the routes relatives to local connected customers and after redistributed in the OSPF’s processes.

We would greatly appreciate your feedback on the design and any suggestion / question that you can give will be welcome.

Everyone's tags (2)

VRF-lite design in a little ISP scenario

Hi Antonio,

VRF lite is for sure the best solution - having in mind some issues with overlapping ip addressing between the clients.

If you have only 4 POPs if think that you can leave BGP.

I think, from your description , that you can use, for example only OSPF and the vrf lite, making your routers as Backbone routers for your client. The POP routers can be backbone (area0) routers, and each client's location a different area.


Re: VRF-lite design in a little ISP scenario


We are going to use a single area 0 in each OSPF process (one for VRF) but we think that Multiprotocol BGP is needed in order to export/import routes from/to VRF’s. Do you agree?

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