From: Bruce Evry (bruceco@xxxxxxxxxx)
Date: Thu Apr 04 2002 - 20:20:21 GMT-3
Hello,
As I understand it:
The "area range" command only works to summarize routes going into
area 0 from an ABR from another OSPF area.
The "summary-address" command only works on an ASBR to summarize
routes that are being redistributed into OSPF from another routing
protocol. (this would include such things as connected or static routes)
The reason behind not summarizing routes once they get to Area 0
is that all the backbone Area 0 routers must have the same database in
order to route properly. (figuring out the Shortest Path First depends on
it)
One of the methods used to get around this is to set up a second
OSPF process and then redistribute the first OSPF process into it, which
allows the second process to use the summary-address command. Then both
OSPF processes are redistributed into the dreaded classful protocol with
subnet masks that IGRP or RIP can understand. (it's either classful or on
a subnet boundary, say /24, that IGRP or RIP is using) Of course you
should always be careful to use route-maps to keep your mutually
redistributing protocols from getting back the same routes they just told
the other guy about... (OSPF does not play well with Distribute-lists
since it does not send Routes but rather sends Link States)
Another method is to redistribute connected (or static if you are
allowed) and use summmary-address statements on these redistributed
routes. (which creates those Null 0 routes automatically, ask your
proctor for estimated miles per gallon :)
Using secondary addresses with /24 masks on interfaces that also
have primary addresses will sometimes work. I have found that ISDN
freezes up when using secondary addresses.
I have heard that you can use Tunnels to solve these problems but
have yet to find a good example. If anyone has one, please send it to me!
It would seem that the methods that use the way OSPF works to
solve the problems would most likely be the method that is being looked
for.
Yours Truly - Bruce Evry, CCTS (constantly continuing to study)
On Thu, 4 Apr 2002, Ram Thunai Selvam-Consultancy-Chennai wrote:
> Even though summary address command is unidirectional and used to summarize
> only the external routes.. When u say summary command of the internal
> networks it will create a null route and say redistribute connected u will
> get in the igrp router...
>
>
> Regds
> Thunai
>
>
> -----Original Message-----
> From: Chua, Parry [mailto:Parry.Chua@compaq.com]
> Sent: Thursday, April 04, 2002 2:41 PM
> To: Mas Kato; guy.lupi@eurekaggn.com
> Cc: ccielab@groupstudy.com
> Subject: RE: OSPF to IGRP redistribution (I know this has been killed, thi s
> is short I promise)
>
> A point to take note is :
>
> Area x range summary route by ABR is directional.
> Summary address route by ASBR is unidirection.
>
> Parry Chua
>
> -----Original Message-----
> From: Mas Kato [mailto:loomis_towcar@speedracer.com]
> Sent: Thursday, April 04, 2002 3:47 PM
> To: guy.lupi@eurekaggn.com
> Cc: ccielab@groupstudy.com
> Subject: RE: OSPF to IGRP redistribution (I know this has been killed,
> thi s is short I promise)
>
>
> [demime could not interpret encoding binary - treating as plain text]
> Guy,
>
> Don't worry, you've already solved this problem when you used the
> 'summary-address' command and redistributed the summary into IGRP. R1's role
> in this case is an ASBR since it's the one speaking to the external
> autonomous system--in this case, IGRP.
>
> When you used the 'area-range' command, you influenced R1s role as an ABR,
> which provided summarization for the benefit of other OSPF-speaking routers
> within the OSPF autonomous system.
>
> So you've got it covered.
>
> Regards,
>
> Mas Kato
> https://ecardfile.com/id/mkato
>
> > "Lupi, Guy" <Guy.Lupi@eurekaggn.com> "'Mas Kato'"
> <loomis_towcar@speedracer.com>Cc: ccielab@groupstudy.com
> >Date: Wed, 3 Apr 2002 16:39:57 -0500
> >
> >Right, that is what I did, R1 is a member of 2 areas, area 1 and area 0.
> >Here is a partial output of "show ip ospf". This is why I don't understand
> >why it isn't working. I thought that as long as the router was an ABR, you
> >could use area range to summarize and inject into IGRP.
> >
> >r1#sh ip os
> > Routing Process "ospf 100" with ID 141.63.10.1 and Domain ID 0.0.0.100
> > Supports only single TOS(TOS0) routes
> > Supports opaque LSA
> > It is an area border and autonomous system boundary router
> >
> >-----Original Message-----
> >From: Mas Kato [mailto:loomis_towcar@speedracer.com]
> >Sent: Wednesday, April 03, 2002 4:30 PM
> >To: Lupi, Guy
> >Cc: ccielab@groupstudy.com
> >Subject: RE: OSPF to IGRP redistribution (I know this has been killed,
> >this is short I promise)
> >
> >
> >Guy,
> >
> >Although router1 is certainly an ASBR, it really doesn't become an ABR
> until
> >it becomes a member of two or more OSPF areas. If you hung another
> >OSPF-speaking router off of router1 and placed it in an area different from
> >router5, you would then see the results of your 'area range' command on
> that
> >new router, because that new router would know how to read the type 3
> >summary LSAs being originated by router1.
> >
> >Regards,
> >
> >Mas Kato
> >https://ecardfile.com/id/mkato
> >
> >> "Lupi, Guy" <Guy.Lupi@eurekaggn.com> "'ccielab@groupstudy.com'"
> ><ccielab@groupstudy.com>Date: Wed, 3 Apr 2002 14:44:12 -0500
> >>Reply-To: "Lupi, Guy" <Guy.Lupi@eurekaggn.com>
> >>
> >>I know this has been covered in detail before, I just want to verify
> >>something. I have the following:
> >>
> >>router2---------router1--------router5
> >>
> >>Router 5 and router 1 are OSPF, router 2 and router 1 is igrp only. I
> know
> >>how to use the secondary address, tunnel, and route-map methods. I know
> >how
> >>to use summary address on router 1 to get connected routes that are not in
> >>OSPF onto router 2. I cannot get routes from router 5 to router 2 using
> >>area range on router 1. Router 1 is an ASBR, and an ABR. I cannot use
> the
> >>area range command to get the route from r5 to r2, and summary address
> >would
> >>never work, but tunnels, route-maps, and secondary addresses work. I
> >>thought that if the router was an ABR, you could do "area-range [area
> route
> >>is from] x.x.x.x x.x.x.x". Thanks.
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:55 GMT-3