From: Joe A (groupstudy@comcast.net)
Date: Tue Nov 12 2002 - 19:06:03 GMT-3
Group,
I don't 'conclusively' agree with the 'aggregation theory' for this
reason: say I have network A.A.A.A /24 from ISP A and network B.B.B.B
/24 from ISP B, and both are chunks out of a class A or B, anything that
can be aggregated on the ISP's egress. If I also advertise A.A.A.A /24
to ISP B and B.B.B.B /24 to ISP A, then, assuming they propagate the
routes I send, their advertisement will be the more specific match, and
I'd be pulling traffic in exactly opposite of what I expected! I
haven't seen this to be the case, so I have to disagree that they will
not propagate a /24. I think if you have a discussion with your
providers and you all understand your goals, they'll either accommodate
you or tell you they can't; either way there should not be any
surprises.
All that aside, these are the problems that the RADB was designed to
solve, right? Get your routing policy documented in a public database
so that all providers can easily see your policy and know that you are
in fact sending out /24s. I'm curious, does anyone out there 'really'
use the RADB when they do their BGP configs?
Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Larson, Chris
Sent: Tuesday, November 12, 2002 10:46 AM
To: 'Paul Jin'; MADMAN; Hamele Kassa
Cc: Brian T. Albert; ccielab@groupstudy.com
Subject: RE: BGP & multihoming
Although most ISP's will accept the /24 it is unlikely that they
propogate it outside of their own AS if the IP block you have was
provided by the ISP. In that case they will accept /24 but will usually
aggregate it to neighbors outside of their own AS.
> -----Original Message-----
> From: Paul Jin [SMTP:pauljin@yahoo.com]
> Sent: Monday, November 11, 2002 8:05 PM
> To: MADMAN; Hamele Kassa
> Cc: Brian T. Albert; ccielab@groupstudy.com
> Subject: Re: BGP & multihoming
>
> I cannot remember who it was for sure, but I had a situation where I
> got for a customer of ours, to advertise a customer owned /24 to ATT
> and they had no problems.
>
> Everything went fine, and a week or two later, I got a call from the
> customer saying there is a particular web site that the executive
> members needed to get to but somehow they could not since the change
> over to ATT.
>
> What we found out was the fact that although ATT took in the /24
> prefix and readvertised it, there was an ISP few hops down that did
> not accept /24. and the web server that the customer needed to get to
> was behind that ISP.
>
> But I cannot remember who it was, and this was back in early part of
> 2001.
>
> Has anyone had any similar experience?
>
> - Paul
>
> MADMAN <dave@interprise.com> wrote:I keep seeing people refer to this
> /19 as the smallest aggregate that will be accepted by a provider
> though I have yet to meet this provider. I have set up several
> customers with dual home full routes and they announce a single /24
> network or maybe a couple but very few have /19 or better. The
> providers I have worked with that accepted the /24 include Qwest, MCI,
> Sprint, Onvoy, and AT&T come to mind.
>
> Dave
>
> Hamele Kassa wrote:
> >
> > Brian,
> >
> > You do not need to secure your own registered address/es(your
> > network
> has to
> > be bigger than /19 space to qualify). The IP address/es assigned to
> > you from your providers (/24 or shorter address space) will work for
> > you as long as you are running BGP(no longer prefix than /24).
> > However you need
> to
> > secure and AS from ARIN(if you are multihomed you will qualify).
> >
> > I hope this helps.
> >
> > HK
> >
> > ----- Original Message -----
> > From: "Brian T. Albert"
>
> > To: "MADMAN"
> > Cc:
> > Sent: Sunday, November 10, 2002 10:51 AM
> > Subject: RE: BGP & multihoming
> >
> > > When you say "your own registered address/es", do you mean
> > > prefixes
> > assigned
> > > to you from your 2 providers or obtained from another authority?
> > > What
> > other
> > > authority can assign you prefixes independent of you providers,
> > > and
> what
> > are
> > > the requirements to obtain them?
> > >
> > > BA
> > >
> > > -----Original Message-----
> > > From: MADMAN [mailto:dave@interprise.com]
> > > Sent: Saturday, November 09, 2002 9:12 PM
> > > To: Brian T. Albert
> > > Cc: ccielab@groupstudy.com
> > > Subject: Re: BGP & multihoming
> > >
> > >
> > >
> > > You don't need NAT if you have your own registered address/es. No
> > special
> > > config required, you simply announce your public address/es
> > >
> > > Dave
> > >
> > > "Brian T. Albert" wrote:
> > >
> > > > In the real world can BGP multihoming to 2 different providers
> > > > be accomplished without NAT for the internal networks? I have
> > > > found
> some
> > > links
> > > > on CCO http://www.cisco.com/warp/public/459/BGP-PIX.htm that
> > > > show
> how to
> > > do
> > > > it with NAT, but is it possible without. If so, can someone
> > > > supply
> some
> > > > config examples or good links.
> > > >
> > > > Thanks
> > > >
> > > > Brian T. Albert
> > > > brian.albert@worldnet.att.net
> > >
> > > --
> > > David Madland
> > > CCIE# 2016
> > > Sr. Network Engineer
> > > Qwest Communications Inc.
> > > 612-664-3367
> > > dave@interprise.com
> > >
>
> --
> David Madland
> CCIE# 2016
> Sr. Network Engineer
> Qwest Communications
> 612-664-3367
>
> "You don't make the poor richer by making the rich poorer." --Winston
> Churchill
>
>
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