From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Mon Nov 11 2002 - 19:40:02 GMT-3
At 2:22 PM -0600 11/11/02, MADMAN 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
Many /24 routes are "grandfathered" from the early days of the Internet.
The original block of addresses for Class C allocation was 192/8.
When the CIDR address conservation work started, around 1991, half of
the global routing table was composed of routes from 192/8. This
block began to be called "The Swamp."
In the Swamp, probably somewhere in Northern New Jersey, is a
sub-block called the "Toxic Waste Dump (TWD)." It's composed of Swamp
routes that are longer than /24, and it once filled half the Swamp.
If you look closely at many provider filtering policies, they may be
more permissive of Swamp routes that were issued before address
conservation was an issue. They would be tougher, for example, on
202/8 and 203/8.
You can get some background from RFC 1517 through 1520, but most of
the policies, to the extent they are disclosed, come from
www.nanog.org. Some filters are listed or linked, and, if you go
into the archives, you'll find discussions of the issues. You can
also go back into the IETF archives and look through the CIDR working
group (now defunct) mailing lists.
>
>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" <brian.albert@worldnet.att.net>
>> To: "MADMAN" <dave@interprise.com>
>> Cc: <ccielab@groupstudy.com>
>> 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
--
Howard C. Berkowitz hcb@gettcomm.com 703-998-5819
Chief Technology Officer, GettLab/Gett Communications
Technical Director, CertificationZone.com
"retired" Certified Cisco Systems Instructor (CID) #93005
books: Building Service Provider Networks (Wiley 2002), WAN
Survival Guide (Wiley 2000), Building Routing and Switching
Architectures for Enterprise Neworks (McMillan 1999), Building
Addressing Architectures for Routing and Switching (McMillan 1998).
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