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Alex
Asked: 2011-11-29 01:42:22 +0800 CST

What routing protocol to use with MPLS?

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My MPLS provider is giving us a choice to use static routes or BGP for our new MPLS setup.
What are advantages/disadvantages of the 2 choices? What is more commonly used?

routing networking mpls bgp static-routes

2 Answers

  1. Best Answer

    MPLS providers will implement MP-BGP in their network to share all routes from and to your different sites.

    They will be separated from other customers' routes by beeing in a "vrf" (vpn), thus eliminating the need of separate IP space (eg all customers can use RFC1918 addresses)

    I think that your provider is giving you the choice of the routing protocol between the PE and the CE router.

    Typical end-to-end synopsis:

    CE --leased line-- PE --backbone link-- P --backbone link-- PE --sdsl line-- CE

    • CE : customer edge, the routers on your sites.
    • PE : provider edge. Router facing customers
    • P : provider router (or "core"). Transit routers, have only knowledge of MPLS and not IP

    Static routing between PE and CE is fine for most deployments, but to be avoided if the wan link is ethernet, because in most cases the PE and the CE routers will have no way to know when the link is down (because of L2 devices which don't propagate link state).

    If your sites are connected through frame-relay or ATM (dsl, T1, T3...), interfaces will go down if link is down.

    To resume:

    • ethernet leased line : go for BGP
    • Frame-relay or ATM leased line, or dsl: static routing will do the trick.
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  2. You typically would need a routing protocol whenever

    • you have many networks/routes to manage
    • you want to implement redundancy and failover paths at the IP routing level
    • you need additional features like Anycast

    You would use static routes if you can't or don't want to manage the additional complexity of dynamic routing.

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