BGP multihoming with two address spaces

Curtis Doty Curtis at
Wed Jan 29 16:03:37 UTC 2014

According to telnet:// and BGP is working as
designed. Your single prepend on one prefix with TWTC causes a slight
preference for LVL3. Add another prepend if you want to further balance
your ingress load away from TWTC.

Or for more coarse adjustment, use the TWTC feature communities to reduce
their local preference below that of customer default (115 for TWTC). Use
4323:100 for transit default.


On Wed, Jan 29, 2014 at 3:32 AM, Joseph Jenkins
<joe at>wrote:

> I am seeking some feedback/help with my BGP configuration.  I am peering
> with two providers level3 and tw.  Unfortunately all of my address spaces
> are preferring the route over tw rather than level3.  I have tried
> Prepending my AS and the carriers AS to the path on the tw side and I see
> those update being accepted by internet routers, but everyone is still
> preferring to install the tw routes rather than level3.  I was trying to
> advertise each provider's address space out their connections and then use
> the other for backup.  Now however everything is coming in through tw and
> no one seems to like level3.
> Thanks in advance for any guidance or assistance.
> Joe

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