Re: diverse multisite advertising?

From: Joe Provo (no email)
Date: Tue Nov 04 2008 - 16:15:08 EST

  • Next message: Charles Wyble: "Re: MPLS for IPv6"

    On Tue, Nov 04, 2008 at 01:07:13PM -0800, Gregori Parker wrote:
    > I've been reading up on BGP and asking around, but still havent found a
    > hard yes/no on this...hopefully someone here can provide clarification.
    > If I have a single ASN and an IP allocation from ARIN, can I advertise
    > one half of my prefix from one site and the other half from another
    > distinct non-connected site using the same ASN? If so, are there
    > implications with mutihoming to all unique ISPs (2 per location)?

    You can do a lot of things. If you want to do it is a matter related
    to what kind of network you run and what your goals are.

    > I seem to remember that an AS Path wouldnt be valid with the same AS
    > appearing more than once in non-sequential order, i.e. at the beginning
    > and the end in this case, but am unable to verify since everything I've
    > been reading up on discusses BGP in single-site terms.

    Your largest concerns will be
    - how do intend your split sites see each other? GRE/IPSec tunnels are
      a popular if potentially fragile answer.
    - deaggregating is antisocial, and depending on your allocation size &
      in what part of the bit-spectrum it lies, you may need to be concerned
      about the deaggregates getting filtered. Assuming a decent answer to
      the first point and you can 'safely' announce the aggregate in both
      spots to attrach traffic beyind the propagation distance of your

    You may wish to consider having the same set of providers in each
    location and examining approaches that make your interior appear more
    coherent than it is [eg deaggregates with sane MEDS and no-export to
    allow you to TE across your paid links, and only let the aggregate
    out past their borders].



                 RSUC / GweepNet / Spunk / FnB / Usenix / SAGE

  • Next message: Charles Wyble: "Re: MPLS for IPv6"

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