From: Nick Shah (nshah@xxxxxxxxxxxxxx)
Date: Wed Jul 10 2002 - 08:27:52 GMT-3
Dude,
I had an escape path defined for myself ...
"where mostly one router belongs to one AS, it may not be practically
possible". That covers your NAP possibility.
Yes, the assumption was made considering iBGP routers, which is quite common
in ISP/NSP environment.
That assumption also includes the fact that this border router has "only
one, this one" external connection (because if it has another connection to
another AS, we will still become a transit AS) as in NAP environment.
So there are quite a few assumptions made. But, technically, this will still
be a *perfect* answer.
Note : I had also mentioned distribute lists(basically all forms of prefix
filters) and community filtering, so I have the bases covered :). So we have
to apply the solution considering all these facts (as and how applicable)
rgds
Nick
----- Original Message -----
From: Carlos G Mendioroz <tron@huapi.ba.ar>
To: Nick Shah <nshah@connect.com.au>
Cc: Tom Larus <tlarus@cox.net>; Jay Hennigan <jay@west.net>; John White
<jan_white7@hotmail.com>; <ccielab@groupstudy.com>
Sent: Wednesday, July 10, 2002 9:14 PM
Subject: Re: As Transit
> How's that ?
> That takes for granted that for being a transit AS you'll be traveling
> through iBGP. That's not always the case.
>
> In a NAP, you may have one router with lots of neighbour ASs, and there
> you might become transit even though you keep synch on.
>
>
> Nick Shah wrote:
> >
> > This is a *perfect* answer in a production world.
> >
> > But in a controlled/lab environment, where mostly one router belongs to
one
> > AS, it may not be practically possible. That leaves only prefix
filtering by
> > no-community and/or all forms of prefix filters (distribute lists etc.)
> >
> > rgds
> > Nick
> >
> > Message -----
> > From: "Tom Larus" <tlarus@cox.net>
> > To: "Jay Hennigan" <jay@west.net>; "John White" <jan_white7@hotmail.com>
> > Cc: <ccielab@groupstudy.com>
> > Sent: Wednesday, July 10, 2002 12:13 AM
> > Subject: Re: As Transit
> >
> > > This is probably not what they are looking for, but if you leave synch
on,
> > > and do not redistribute bgp routes into you igp, you will definitely
NOT
> > > become a transit AS.
> > >
> > > Is the real answer to set all your incoming bgp routes to no-export?
> > >
> > > ---- Original Message -----
> > > From: "Jay Hennigan" <jay@west.net>
> > > To: "John White" <jan_white7@hotmail.com>
> > > Cc: <ccielab@groupstudy.com>
> > > Sent: Tuesday, July 09, 2002 12:39 AM
> > > Subject: Re: As Transit
> > >
> > >
> > > > On Tue, 9 Jul 2002, John White wrote:
> > > >
> > > > > Hi Guys,
> > > > > I'm doing Cisco Aset lab.One of question is to prevent our AS from
> > > becoming
> > > > > Transit AS, but your not allowed to use AS path filtering.
> > > > > Learning routes from outside shuould be still possible.
> > > > > Somehow I can't think of anything else. Distribution
list?Community
> > > list?
> > > >
> > > > Hint:
> > > >
> > > > Look at the well-known community attributes.
> > > >
> > > > --
> > > > Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net
> > > > NetLojix Communications, Inc. - http://www.netlojix.com/
> > > > WestNet: Connecting you to the planet. 805 884-6323
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