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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