We're Sorry, Full Content Access is for Members Only...

If you like to keep on reading, Become a Member Now! Here is Why:

  • Learn any CCNA, CCNP and CCIE R&S Topic. Explained As Simple As Possible.
  • Try for Just $1. The Best Dollar You've Ever Spent on Your Cisco Career!
  • Full Access to our 622 Lessons. More Lessons Added Every Week!
  • Content created by Rene Molenaar (CCIE #41726)


444 New Members signed up the last 30 days!


100% Satisfaction Guaranteed!
You may cancel your monthly membership at any time.
No Questions Asked!

Forum Replies

  1. Hi Hamood,

    Good question, there’s a good explanation for this:

    1. iBGP requires a full mesh of peerings because of iBGP split horizon. This is why we use loopback interfaces instead of physical interfaces for the peering. Physical interfaces can go down, loopbacks can’t (unless you shut them). In this example I could have used physical interfaces since there is only one link between R2-R3 and R3-R4, if we had a link between R2-R4 then it would have been a must.

    2. When R4 (or R2) advertises its network on the loopback interface to R3 then R3 will store it in its

    ... Continue reading in our forum

  2. Hello Rene,
    in the example above i got confused with the next-self-hop command. As we see that R4 have not learned the network!!! i wonder why R4 did not learn it from IGP/iBGP? my question is does IGP carry and advertise iBGP routes? can you please explain the benefit of the next-self-hop command ??? Thanks


  3. Thanks for the long discussion, Rene.

    Yeap ! I will keep doing simple labs, until I get a better understanding of adavanced stuff, like BGP FREE CORE, SPLIT HORIZON, MPLS VPN, … :smile:

  4. Hello Minh,

    It sounds like you have a good understanding of these concepts :slight_smile:

    ISPs / service providers often use MPLS in their core networks yes. One of the advantages is that you don’t have to run iBGP on each and every core router. I have a lesson where I explain this:


    On the P and PE routers, we use an IGP like OSPF or IS-IS, on the PE routers we use iBGP.

    VRFs are often used in MPLS VPN where you want customer routing to be separated 100%. You don’t really need this for just Internet access. With MPLS VPN,

    ... Continue reading in our forum

106 more replies! Ask a question or join the discussion by visiting our Community Forum