North American Network Operators Group

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Re: Static routes in an AS vs BGP advertised routes

  • From: Greg Maxwell
  • Date: Wed Aug 08 10:41:40 2001

On Wed, 8 Aug 2001, Murphy, Brennan wrote:

> of the ISPs. But the ISP taken out by the asteroid is
> still advertising the full /19.
> Under the circumstances (loss of life, hysteria, sub-optimal
> routing), would it be appropriate to ask the unfortunate
> ISP to create a static route on their network to push
> traffic destined for that particular /24 over to the other
> ISP's network?  This way, the /19 advertisements can

Of course, this would only be sure to work if the ISPs in question were
peering. Otherwise, you could likely create loops.

> Will ISPs make these types of accommodations? Suppose
> the reason was less unexpected than an asteroid.  For example,

If they have just been hit by an asteroid, they might be worrying about
more then adding routes for you, and may not do it in a timely fashion.

Your immediate best course (best from the "you can only trust yourself"
school of thought) would be to have an established way to control
their advertisements (communities) and withdraw your /19
announcement from their network.

For example, you could advertise both your /19s and your /24s, using
communities to prevent route table pollution. After someone sets you up
the bomb, you drop the one /19 advertisement, and potentially change the
community on the surviving advertisements to keep some traffic flowing
through that provider.