ISP best practices

Jon Lewis jlewis at
Thu May 21 09:00:09 CDT 2009

On Thu, 21 May 2009, Philip Lavine wrote:

> I am sure this has been asked 10 to the 1 millionth power times, however 
> may be the rules have changed. I am looking to set up a really small ISP 
> with a few /24's. I want to host DNS as well. Is there any 
> whitepapers/howtos/best practices on setting up multihomed BGP and DNS 
> with BIND so I don't blow up the Internet.

A few minutes with google would probably find sample BGP multihoming 
configs.  The big things to avoid are unnecessary deaggregation and 
announcing routes received from one provider to the other.

i.e. If you have a /22 of IP space, you may use/see that as 4 /24's or a 
larger number of smaller subnets, but where eBGP is concerned, you should 
announce just the /22 route and keep your subnetting to yourself.

If you have competent providers, they won't accept routes from you that 
they're not expecting, which will stop you from offering transit to them 
by announcing routes received from your other provider.  Still, it's 
better to get your config done right than rely on your providers to ignore 
what you shouldn't be advertising.

  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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