Forum Replies

  1. Hi Shaun,

    For CCNP ROUTE this will be enough. They expect you to have an "idea" what MPLS is about but you don't have to configure anything. If you want to learn what MPLS VPN is about, just follow all the lessons in this overview:

    It will explain all the MPLS VPN scenarios.


  2. Hi Rene / Andrew

    What are some great books / sources to master MPLS and related advance technologies used in today's Enterprise and SP networks ?


  3. Jon says:

    Hi @kayoutoure,

    In this article we are starting with the idea to remove BGP from the network core. This is because the core can be very large and we don't want to have to make many manual changes each time something is modified.
    Our objective is to let the PE routers talk BGP to other PE routers and remove the requirement for P routers to talk BGP. We could have many P routers in the path between two PE routers (e.g. PE-P-P-P-P-P-P-P-PE) so this would be a great optimisation.

    So your first point is correct. BGP prefixes are learned from PE to PE, not via the P routers.

    Regarding GRE, don't worry about this too much. It is used as one example of how we could stop using BGP on the P routers. We are meant to consider that using MPLS in the core is similar to using GRE in the core as they are both methods of allowing PE routers to handle all the BGP routing logic and the P routers just forward data in a "dumb" way between PE routers.

    The reason we see many more MPLS cores than GRE cores is that there are some extra advantages to using MPLS such as better performance in large networks but, in our lesson, they have both achieved the same thing; removing BGP from the P router core.

    I hope this helps,

  4. Hi @kayoutoure

    It might help to think about this the other way around, let's say we don't use MPLS but BGP on all P and PE routers. This means that:

    • The P routers have to do a lookup in their routing tables for every destination.
    • The P routers have to know about every destination...this means you'll have to redistribute customer information into BGP.
    • iBGP has to be a full mesh so if you add another P router in your network, you'll have to establish neighbor adjacencies with all other iBGP routers. You can make your life a bit easier with route reflectors and confederations but it's still a lot more work than configuring a router with an IGP like OSPF + MPLS.

    There are a lot of different logical topologies you can run on top of MPLS. For example, services like E-line, E-tree and E-lan are also often used on top of MPLS.

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