[afnog] Internet Traffic distribution management

Mark Tinka mark.tinka at seacom.mu
Wed Sep 30 06:06:54 UTC 2015



On 29/Sep/15 16:59, Frank Kuse wrote:

>
>
> Each link is a minimum of STM16.

I'm assuming that you have a discrete eBGP session per STM-16 link.

If so, why don't you reduce the number eBGP sessions so that instead of
8x, you have 4x? You can do this in one of two ways:

    a) Run a POS LAG with your provides to whom you have multiple links.
Assuming both your router and theirs can support this, you end up with a
single logical
        link that is equal to the sum of each individual STM-16
combined. This way, routing becomes easier and you end up with a larger
link that will support ECMP.

    b) The other option is to run eBGP Multi-Hop, running the BGP
session across a Loopback interface on either side, and using static
routing on both sides so that
        you load balance traffic across all links to/from the same
upstream. Again, this has the benefit of having a single eBGP session
for all links to the same
        upstream, while providing ECMP.

With the increased capacity and the halving of all your eBGP sessions,
you can have an easier time doing traffic engineering using classic
methods such as AS_PATH prepending, safely de-aggregating and/or
discriminate announcing of prefixes amongst the providers.

Hope this helps.

Mark.
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