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.