From: Brian McGahan (brian@cyscoexpert.com)
Date: Fri Oct 25 2002 - 17:38:18 GMT-3
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!?
> > > Yahoo! BB is Broadband by Yahoo! http://bb.yahoo.co.jp/
This archive was generated by hypermail 2.1.4 : Tue Nov 05 2002 - 08:35:57 GMT-3