[149204] in North American Network Operators' Group
Re: Please help our simple bgp
daemon@ATHENA.MIT.EDU (Joel Maslak)
Mon Jan 30 22:06:38 2012
In-Reply-To: <CACwqZxjBp_R_b-r-9zdB+4xSO1mPmfaYhg8nuDwnt7g2i6RXTg@mail.gmail.com>
Date: Mon, 30 Jan 2012 20:06:14 -0700
From: Joel Maslak <jmaslak@antelope.net>
To: Ann Kwok <annkwok80@gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mon, Jan 30, 2012 at 7:27 PM, Ann Kwok <annkwok80@gmail.com> wrote:
> We discover the routes is going to ISP A only even the bandwidth 100M is
> full
There are several ways to handle this is, if you have at least two
/24s of space.
Let's say you just have two /24s, both part of the same /23.
Option 1:
Announce m.m.m.m/24 with no path prefixing on ISP A.
Announce m.m.m.m/24 prefixed with your own ASN one or two times on ISP B.
Announce n.n.n.n/24 with no path prefixing on ISP B
Announce n.n.n.n/24 prefixed with your own ASN one or two times on ISP A.
Most of the internet would probably prefer A for m.m.m.m/24, and
prefer B for n.n.n.n/24. But if either A or B went down, there would
still be a reachable route.
Option 2:
Announce m.m.m.m/23 on both ISP A and B
Announce m.m.m.m/24 on ISP A
Announce n.n.n.n/24 on ISP B
The n.n.n.n/24 which is part of m.m.m.m/23 would use ISP B for inbound
traffic, while ISP A would be used for m.m.m.m/24. If either A or B,
the less specific /23 would provide a backup path.
> Can we set the weight to change to ISP B to use ISP B as preference routes?
Not really. You may be able to set a community that controls how ISP
B advertises the routes or preferences your traffic. Weights
generally aren't used for path selection.
