redistribution of iBGP routes into other routing protocols !!!!!

Extract from MPLS VPN Architecture chapter 9....



"Contrary to the traditional BGP operation in which the internal BGP routes are not allowed to be redistributed into other routing protocols, this restriction is lifted in the MPLS/VPN environment. The VPN routes received by a PE router through an internal MP-BGP session from another PE router can be redistributed into other routing protocols."

 

Is it true .... kindly comment  ???

Comments

  • Very much true.  Because in MPLS environments, BGP is the primary push of VPNv4 routes across the MPLS provider.  Keep in mind the placement of routers is "inverted" in the MPLS world.

    Normal environments, BGP is run on the edge towards the outside with an IGP on the inside NOT wanting to redistribute.

    In MPLS environments, BGP is still run on the edges, but our redistribution concerns is pointed towards the OUTSIDE (towards customers) instead of into our own IGP.

    HTH,

    Scott







    ----- Original Message -----
    From: "mukarram" <[email protected]>
    Sent: Thu, September 24, 2009 23:50
    Subject: [CCIE R&S] redistribution of iBGP routes into other routing protocols !!!!!


    Extract from MPLS VPN Architecture chapter 9....



    "Contrary to the traditional BGP operation in which the internal BGP routes are not allowed to be redistributed into other routing protocols, this restriction is lifted in the MPLS/VPN environment. The VPN routes received by a PE router through an internal MP-BGP session from another PE router can be redistributed into other routing protocols."

     

    Is it true .... kindly comment  ???



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  • this line should explain this.

    "The VPN routes received by a PE router through an internal MP-BGP session from another PE router can be redistributed into other routing protocols"

    so it's vpnv4 internal routes can be redistributed.

    i may not be right but it would be used when one side of the CE router is running a IGP and other side of the CE router is running BGP. 

    scott can comment on it if it is possible.

  • And that will most likely be true as well.   If a company is running BGP with their SP (most common scenario) they will probably still be running an IGP in the rest of their network, so they'll redistribute.

    In that kind of design though, the routes that are coming IN via bgp are technically that customer's own routes anyway, so they aren't looking at a problem of too many routes being redistributed (or if they do, it's their own fault!)

    So yes, we're seeing, in the real world, a different set of criteria for the "redistribute from bgp to igp" mindset than we used to.

    In the lab exam, we'll probably more likely see the BGP to IGP handoff at the PE router just for giggles.

    HTH,

    Scott






    ----- Original Message -----
    From: "ccienotes" <[email protected]>
    Sent: Fri, September 25, 2009 23:05
    Subject: Re: [CCIE R&S] redistribution of iBGP routes into other routing protocols !!!!!


    this line should explain this.

    "The VPN routes received by a PE router through an internal MP-BGP session from another PE router can be redistributed into other routing protocols"

    so it's vpnv4 internal routes can be redistributed.

    i may not be right but it would be used when one side of the CE router is running a IGP and other side of the CE router is running BGP. 

    scott can comment on it if it is possible.



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  • Hi Scott,

    my concern is over this statement

    Contrary to the
    traditional BGP operation in which the internal BGP routes are not
    allowed to be redistributed into other routing protocols

    U r right we dont need to redistribute in Non-MPLS environments on edges, but it is possible to do so......

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