I was totally involved two years ago in setting up a BGP peering
with both UUNET and Sprint at the same time for an ISP.
At that time I remember very well that they accept anything less
than /19.
Today I'm dealing now with Teleglobe and also they accept
blocks less than that.
When we talk about ISP peering with Carriers especially more
than one, the ISP sometimes needs to advertise some of his /19
blocks to one and rest to another.
----- Original Message -----
From: "Thanatos" <[EMAIL PROTECTED]>
To: "J Roysdon" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Sunday, January 21, 2001 11:03 PM
Subject: Re: AS numbers - Is there a global crisis?
> I could not give you exact information, when I have looked at peering
> policies in the past it normally depends on the type of address space
> involved. If the addresses came from what was typically a Class C space
> they may not require a large aggregation of IP addresses. It is pretty
much
> standard that coming from what was typical Class A space that anything
> smaller than a /19 would not be advertised or accepted. I know of a
> broadband cable ISP that ran into this aggregation problem with Verio.
None
> of their users could reach anything within Verio's network (Or AT&T for
that
> matter)
>
> The following link has an example of Verio's peering policy, which I am
> assuming is pretty standard as peering policies go.
> http://info.us.bb.verio.net/routing.html#PeerFilter
>
> -- Kevin.
>
> "J Roysdon" <[EMAIL PROTECTED]> wrote in message
> 94gm53$u1$[EMAIL PROTECTED]">news:94gm53$u1$[EMAIL PROTECTED]...
> > I've heard that most ISPs will filter less than /19. If this is true,
> then
> > only the ISP who owns the aggregate route will get heard by most other
> ISPs.
> >
> > Can anyone confirm at which point most ISPs filter? I know at a minimum
> > most won't accept more specific than /24.
> >
> > I finally got some evil internal routing & vpn issues taken care of, and
> > should be finally implementing BGP with Sprint & UUNET (geeze, it's been
> > forever dealing with these internal issues). If nothing else, I'll ask
> > their BGP folks what they filter at.
> >
> > I can also confirm that about double the ASN's in use (9731) have been
> > handed out. We were given ASN 18506 in September.
> >
> > --
> > Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+
> > List email: [EMAIL PROTECTED]
> > Homepage: http://jason.artoo.net/
> > Cisco resources: http://r2cisco.artoo.net/
> >
> >
> > ""Howard C. Berkowitz"" <[EMAIL PROTECTED]> wrote in message
> > news:p05001919b68e6e6b973a@[63.216.127.98]...
> > > >Brian,
> > > >
> > > >Hi! Funny you bring this up, I just got a phone call on it today.
> > > >Basically, you can have two seperate ISPs and have incoming redundant
> > > >connections without using BGP. ISP1 will provide a block of IPs from
a
> > > >portion of their CIDR block to the "company." Since this is part of
> > ISP1s
> > > >CIDR block, they already broadcast a route to the rest of the
internet
> > > >containing the company's block of IPs.
> > >
> > >
> > > >
> > > >ISP2 will then also broadcast a route to ISP1's block of IPs (just
the
> > > >block!!!). The tricky part comes when you try to do load balancing
> > between
> > > >the two for incoming traffic!!!
> > > >
> > > > I am making several assumptions here (that the ISPs will play nice
> with
> > > >each other among other things).
> > > >
> > > ISP1, however, MUST advertise not its aggregate alone, but both its
> > > aggregate and the more-specific customer block that also is
> > > advertised by ISP2.
> > >
> > > Assume the following:
> > >
> > > ISP1 has the block 192.168.0.0/16. This is the only block it
> advertises.
> > >
> > > It delegates 192.168.2.0/24 to the customer.
> > >
> > > ISP2 advertises 192.168.2.0/24.
> > >
> > > So in the global routing table, there will be two routes:
> > >
> > > 192.168.0.0/16 ISP1
> > > 192.168.2.0/24 ISP2
> > >
> > > Since 192.16.2.0/24 is more specific than 192.168.0.0/16, the rest of
> > > the world will send ALL 192.168.2.0/24 traffic to ISP2.
> > >
> > > By having ISP1 advertise both its aggregate and the more-specific,
> > > the routing system conceptually will contain:
> > >
> > > 192.168.0.0/16 ISP1
> > > 192.168.2.0/24 ISP1
> > > 192.168.2.0/24 ISP2
> > >
> > > Other AS will install the ISP1 route to 192.168.2.0/24 if their
> > > connectivity to ISP1 is better than their connectivity to ISP2, and
> > > vice versa.
> > >
> > > _________________________________
> > > FAQ, list archives, and subscription info:
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> > >
> >
> >
> >
> >
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