Re: Multihoming an end user
Eric Cunnningham wrote:
My understanding was that if the addresses weren't specifically
allocated to us straight from ARIN, we couldn't truly multihome.
Incorrect. Lots of multihomed networks on the Internet are using
addresses assigned by a provider.
Otherwise our second ISP would try to route to our first ISP's addresses
through that first ISP rather then direct through their link to us.
Standard rules of IP routing apply, particularly "most specific route
wins". If you announce a /24 to ISP1 and ISP2, ISP2 will have the
specific route pointing directly to you, and you will receive the
traffic directly.
If we apply for an ASN, can we associate our first ISP's /29 (or /24 if
need be) to our ASN?
You'd use the ASN to run BGP with ISP1 and ISP2, and announce the /24
(/25 and longer won't make it through filters) to each.
Does our primary ISP need to release it to us or
be multihomed themselves?
They need to assign you the /24, obviously, and for best results they
need to let you announce the /24 through them and they should be
multihomed themselves. If they are not multihomed or otherwise speaking
BGP with their provider, you'll have major challenges to overcome,
and/or may find that ISP2 is now the primary inbound provider for your
traffic.
Once this is all said and done, is BGP4 on zebra the way to go or is
there something better?
Zebra or Quagga, though I'll take the counter position of others for a
minute and say that multihoming over consumer-grade connections is a bad
idea, if you can get the providers to run BGP with you at all over them.
pt
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