From: Charlie Winckless (CharlieW@xxxxxxxxxxx)
Date: Fri Apr 27 2001 - 14:18:54 GMT-3
I used to work for VERIO. At that time they would not
router smaller than /19 on their backbone.
This may have changed.
> -----Original Message-----
> From: Murphy, Brennan [mailto:Brennan_Murphy@nai.com]
> Sent: Friday, April 27, 2001 10:46 AM
> To: 'Michelle T'; 'ccielab@groupstudy.com'
> Subject: RE: real world BGP question
>
>
> I guess that is my real question: what is the longest prefix that
> is exchanged among/between major carriers.
>
> The real world example here is what if you had 4 server farms
> answering
> to one DNS name: ftp.foo.com You have Round Robin DNS running
> round trip times to match a user with their nearest server farm....
> so it sends back the closest/fastest IP. The question is, how
> big do those
> subnets for the server farms have to be in order to be maximally
> advertised throughout the internet?
>
> So, I've seen two answers in this thread /20-21 or /24. I wonder
> where I could find the real answer? Maybe Halabi has a link in the
> back of his book to an organization that maintains info such as
> this.
>
> Any more input is greatly appreciated. Thanks to all who have
> responded.
> I figured this question was a relavant BGP question relating
> our studies
> to an actual scenario.
>
>
>
> -----Original Message-----
> From: Michelle T [mailto:mtruman@mn.mediaone.net]
> Sent: Friday, April 27, 2001 12:06 PM
> To: Murphy, Brennan; ccielab@groupstudy.com
> Subject: RE: real world BGP question
>
>
> /24 is the longest prefix you will see accepted by nearly any
> carrier out
> there. Many will only accept /20 or /21. All perform
> aggregation to some
> degree, though exception routing is allowed to send the /24's
> (/23, /22,
> etc) out to the ISP peers when the customer is multi-homed two diverse
> carriers.
>
> I can tell you that I work for a Tier 1 ISP and we accept
> longer prefixes
> for many customers who are multi-homed just to us. They use
> the various
> subnets as a simple method of controlling inbound traffic
> distribution, to
> enact policy, etc...
>
> Many times we see multi-homed (dual-ISP) customers advertise
> an aggregate
> /16 or longer and also advertise /24's for the same reaason (policy,
> distribution, etc).
>
> Michelle Truman
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Murphy, Brennan
> Sent: Friday, April 27, 2001 10:28 AM
> To: 'ccielab@groupstudy.com'
> Subject: real world BGP question
>
>
> What is the smallest subnet that major carriers will exchange with one
> another? /24..../26.../27?? I know that the real issue is
> the size of
> the route table.
>
> I'm just wondering about the reallity of scenarios that
> Habali describes
> where an institution advertises an aggregate with specific subnets.
>
> I know that when you're multi-homed to a carrier, that carrier will
> sometimes
> take your /26 and /27 nets to help route inbound traffic but
> that carrier
> will not advertise those nets to its neighbors.....at least
> thats what I've
> heard.
>
> Anyone have any real world experience with this? Or is there a URL
> I could read up on?
>
> Thanks,
>
> BM
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