From: De Witt, Duane (duane.dewitt@siemens.com)
Date: Thu Oct 20 2005 - 10:02:49 GMT-3
I've never thought about doing it like that. All the MPLS implementations I've done I've had the IGP (OSPF or ISIS) handle routing for the core which would include links and loopbacks. Then BGP would handle all the prefixes from outside the core.
I'll give some IGP's a try only advertising loopbacks and see how it works :)
-----Original Message-----
From: Danny Muizebelt [mailto:Danny.Muizebelt@osiatis.at]
Sent: 20 October 2005 02:57 PM
To: De Witt, Duane; McCallum, Robert; Cisco certification
Subject: AW: ISIS --- advertise passive-only
Hi Duane,
I don't think so. I can filter any routing update from my EIGRP advertisements except my loopback interfaces. For my neighbour router the only thing which is interesting is the remote network and the next hop. Next hop is known because it's connected. I don't think a remote router on the other side of your network is really interested in the remotely connected point-to-point networks of the router originating the loopback prefix.
And don't forget to use the "no synchronization" in the BGP config, else it wouldn't work. :)
-Danny
> -----Urspr|ngliche Nachricht-----
> Von: De Witt, Duane [mailto:duane.dewitt@siemens.com]
> Gesendet: Donnerstag, 20. Oktober 2005 14:37
> An: Danny Muizebelt; McCallum, Robert; Cisco certification
> Betreff: RE: ISIS --- advertise passive-only
>
> Hi
>
> I'm understanding that you want your IGP to provide connectivity to
> the
> loopbacks so that BGP can handle all of the edge prefixes? Surely to
> provide reachability to the loopbacks the links between the routers
> would also need to be advertised by the IGP?
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> Danny Muizebelt
> Sent: 20 October 2005 02:28 PM
> To: McCallum, Robert; Cisco certification
> Subject: AW: ISIS --- advertise passive-only
>
> Hi Robert,
>
> If I don't put the "ip router isis" no neighbour relationship is
> possible over this interface. But while configuring this neighbour
> relationship I also add the connected network/interface to the
> link-state database. For a BGP network I only need loopback
> addresses
> and all other internal networks would only clutter up my ISIS table.
>
> For instance, which interfaces are on passive? Loopback and customer
> interfaces. Which networks are interesting for BGP? Loopback and
> customer networks.
>
> So I think that the "advertise passive-only" option is pretty nifty
> to
> separate the tasks each routing protocol is supposed to do. Too bad
> they
> didn't think sooner of it.
>
> I don't think it's possible to set up a some sort of clns unicast
> neighbour statement without using the "ip router isis" command.
>
> -Danny
>
>
> > -----Urspr|ngliche Nachricht-----
> > Von: McCallum, Robert [mailto:robert.mccallum@thus.net]
> > Gesendet: Donnerstag, 20. Oktober 2005 14:15
> > An: Danny Muizebelt; Cisco certification
> > Betreff: RE: ISIS --- advertise passive-only
> >
> > I must be missing something here but to advertise a connected
> > network in
> > isis you must place the ip router isis command on the interface.
> If
> > you
> > don't want to advertise a certain interface then just don't place
> > that
> > command on the interface.
> >
> > Robert McCallum CCIE #8757
> >
> >
> >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > > Behalf Of Danny Muizebelt
> > > Sent: 20 October 2005 12:13
> > > To: Cisco certification
> > > Subject: ISIS --- advertise passive-only
> > >
> > > Hi Group,
> > >
> > > I was looking for a feature in ISIS where I could suppress
> > > the networks of connected interfaces toward neighbour ISIS
> > > routers. I only wanted the loopback addresses advertised by
> > > the IGP so BGP would take care of the rest.
> > >
> > > It started off very well on my 1841 with 12.4(1a) loaded (There
> is
> > no
> > > 12.2T) and what did I find?
> > >
> > > advertise Control which IP routes flow in L1 and L2 LSPs
> > > R8(config-router)#advertise ?
> > > passive-only only interface address of passive interfaces
> > > R8(config-router)#advertise passive-only ?
> > > <cr>
> > > R8(config-router)#advertise passive-only
> > >
> > > And this works like a charm:
> > >
> > > R8.00-00 0x000000F1 0x71DB 993
> > > 0/0/0
> > > Auth: Length: 7
> > > Area Address: 10
> > > NLPID: 0xCC
> > > Hostname: R8
> > > IP Address: 10.100.100.8
> > > Metric: 0 IP 10.100.100.8 255.255.255.255
> > > Metric: 10 IS R8.02
> > > Metric: 10 IS R8.01
> > > R8.01-00 0x000000E9 0xCFD7 1142
> > > 0/0/0
> > > Auth: Length: 7
> > > Metric: 0 IS R8.00
> > > Metric: 0 IS R9.00
> > >
> > > So I was slightly depressed when I discovered that the 12.2T
> > > release didn't have this feature or any other possibility to
> > > suppress advertised networks.
> > >
> > > It seems to me that "advertise passive-only" was really
> > > implemented for ISIS/BGP or ISIS/MBGP combos for larger ISP
> > > backbone networks.
> > >
> > > Or is there another way of only advertising your loopbacks over
> > ISIS?
> > >
> > > Cheers,
> > >
> > > Danny
> > >
> > >
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