Anycast 101

Fri Dec 17 14:41:57 UTC 2004

Iljitsch van Beijnum wrote:

> Well, there may be only three "at" the LINX, but from where I'm 
> sitting, 7 are reachable over the AMS-IX, 4 over ISP #1 and 1 over 
> ISPs #2 and #3, respectively.
>
> Interestingly enough, b, c, d and f all share this hop:
>
>  6  portch1.core01.ams03.atlas.cogentco.com (195.69.144.124)
>
> (195.69.144.0/23 is the AMS-IX exchange subnet.)
>
I'm beginning to wonder whether you're just an agent provocateur.

Assuming that your link to AMS-IX fails, your redundant attachments to
the world will provide the reachability to those same 7 via your other
links.  All that shows is those 7 are topologically closer via that
path.  You don't seem to have 13 paths.  So?

FWIW, I see all DNS roots via the same BellSouth path.  IFF BellSouth
fails, I'm sure that other paths will pick up the slack.  I'm not
worried, because I've experienced BellSouth failures in the past, and
I've tested dropping each of my links from time to time to ensure that
routing works and I'm getting what I'm paying for....

Do you actually do any engineering, or just kibitzing?

-- 
William Allen Simpson
    Key fingerprint =  17 40 5E 67 15 6F 31 26  DD 0D B9 9B 6A 15 2C 32