From: michael schwarz (flying_eskimo@hotmail.com)
Date: Fri Oct 25 2002 - 17:54:16 GMT-3
Brian thanks for the clarification, i carelessly grouped eigrp and ospf here
when they are indeed very different in the way they handle distribute lists.
So Tom to answer your original question:
Simple way to achieve the "listen for route updates but don't send"
behavior:
RIP/RIPv2: Passive-Interface
IGRP: Passive-Interface
EIGRP: Dist list out
OSPF: 'ip ospf database-filter' command
BGP: Filtering enchilada of your choice
For spits and giggles anyone know how this behavior is achieved in IS-IS?
michael
----- Original Message -----
From: "Brian McGahan" <brian@cyscoexpert.com>
To: "'michael schwarz'" <flying_eskimo@hotmail.com>;
<ccielab@groupstudy.com>
Sent: Friday, October 25, 2002 1:38 PM
Subject: RE: passive-interface command
> Michael,
>
> Distribute-list out does not work that way in OSPF. Since OSPF
> is link-state, all routers within a link-state area must have the same
> view of the topology in order to correctly compute SPF. Distribute-list
> out in OSPF is for redistribution on an ASBR.
>
> http://www.cisco.com/warp/public/104/9.html#Q9
>
> Distribute-list in can be applied to OSPF to prevent a prefix
> from being installed in the routing table, however the LSA still
> populates the OSPF database.
>
> http://www.cisco.com/warp/public/104/26.html#7
>
> To get the same effect that passive-interface does in RIP or
> IGRP, use the command 'ip ospf database-filter'. This allows the
> establishment of adjacency, however LSAs are not sent out.
>
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_
> reference_chapter09186a00800917e6.html#xtocid18
>
> Database filter can also be applied to the neighbor.
>
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_
> reference_chapter09186a00800917e6.html#28694
>
> There is also a new feature of filtering LSA type 3 on an ABR.
> I don't think it's supported in any 12.1 trains, so it's not likely to
> appear in the lab.
>
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_
> guide09186a0080087be9.html
>
>
> HTH
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> Voice: 847.674.3392
> Fax: 847.674.2625
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > michael schwarz
> > Sent: Friday, October 25, 2002 1:58 PM
> > To: ccielab@groupstudy.com
> > Subject: Re: passive-interface command
> >
> > You can use passive int for eigrp/ospf but it does not operate the
> same as
> > RIP and IGRP.
> >
> > With RIP and IGRP you are correct in saying that the configured
> interface
> > "listens" wisely for updates but does not talk, or send updates.
> >
> > However EIGRP does not operate that way.
> >
> > In EIGRP and OSPF configuring an interface as passive effectively
> shuts
> > down
> > the sending and recieving of hello packets. Obviously this causes any
> > neighbors hanging off that interface to be unable to form an adjacency
> > with
> > this router, therefore you got nothing. Basically if you want to
> "turn
> > off"
> > the protocol on a specific interface then use passive-int on OSPF and
> > EIGRP.
> > In ospf though best practice would be to specifically enable ospf per
> int
> > using the net/area command. I believe that OSPF also views that
> > passive-interface as a stub network in the linkstate db.
> >
> > BGP does not have a passive command that i know of. Someone please
> > correct
> > me if im wrong. You probably want to use neighbor shutdown or one of
> 20
> > million possible ways of filtering bgp routes depending on what you
> are
> > doing.
> >
> > If you want EIGRP or OSPF to act like RIP/IGRP (listen wisely but not
> > talk)
> > you need to use a distribute list out. The hellos are not suppressed
> so
> > adjacencies form, routes are recieved from neighbors, but not SENT.
> and
> > this horse is now dead.
> >
> > michael
> >
> > ----- Original Message -----
> > From: "Jay" <ccienxtyear@hotmail.com>
> > To: "Tom Young" <gitsyoung@yahoo.co.jp>; <ccielab@groupstudy.com>
> > Sent: Thursday, October 24, 2002 9:53 AM
> > Subject: Re: passive-interface command
> >
> >
> > > what I think makes the different is that OSPF has areas. So on a
> router,
> > if
> > > you have 2 ethernet interfaces and you are running OSPF and have
> defined
> > an
> > > area for the subnet thats on one of the ethernet interface, OSPF
> will
> > not
> > > send hellos to the other ethernet interface since it is not part of
> an
> > OSPF
> > > area. Unlike Rip, IGRP & EIGRP, theres no areas. When you configure
> > these
> > > protocols on a router, it will send hellos, broadcast to all
> interfaces
> > on
> > > this particular router, unless you passive them.
> > >
> > > -Jay
> > >
> > >
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Tom Young" <gitsyoung@yahoo.co.jp>
> > > To: <ccielab@groupstudy.com>
> > > Sent: Wednesday, October 23, 2002 10:42 PM
> > > Subject: passive-interface command
> > >
> > >
> > > > Hi, group
> > > >
> > > > Sorry for a simple question about the passive-interface
> > > > command, I know in the sence of distributing different
> > > > routing protocol we oftenly use the passive-interface
> > > > command, and I notice it is always rip , igrp, and eigrp
> > > > use it, (surpess rip eigrp's message to other area) for
> > > > the ospf and bgp it is always not use it, I don't know
> > > > why...
> > > > If you said rip and eigrp has the broadcast or
> > > > multicast address, but the ospf also has multicast address
> > > > right?
> > > >
> > > > Thanks alot
> > > >
> > > > __________________________________________________
> > > > Do You Yahoo!?
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This archive was generated by hypermail 2.1.4 : Tue Nov 05 2002 - 08:35:57 GMT-3