From: Mohamed Heeba (MAHeeba@xxxxxxxxxxx)
Date: Sun May 13 2001 - 09:58:13 GMT-3
> Hi mas ;
> thx for the help ...finally i reached something ..all clear but small
> single problem in the end of this mail
>
> 1-summary address command of any of the summarization protocols should
> only be used to summarize INTO the domain (this means the external routes
> of the OSPF to himself)..revise Doyle last example in the redistribution
> chapter ,Very clearly mentioned that the way u summarize ISIS to the RIP
> is by using static routes !!!!
> 2-if you do redist mutual with one single point of redist ,you DONNT have
> to put filters ,unless u summarize ,the summarization only will create
> feedback routes which is not recommended to leave (even if the null0
> static route is creatd in the routing table)
> assume EIGRP and OSPF ,each will summarize the other one to himself ,at
> that time only the route feedbck will be propagated ...you can use
> router ospf 100
> redist eigrp 64 sub
> distribute-list 1 out eigrp 64
>
>
> the filter should only allow the eigrp original networks ,this will preven
> the feedback route from propagating back to the OSPF .
> 3-if two points of redist ,i prefer to change the distance to keep the
> redundant links working ,the filters will work fine but it will remove any
> redundancy (explained very well in Doyles book )
>
>
> finally the problem ,Wat if the static routes are not allowed ??? i guess
> either the ip default-network or propagating default should be used......
>
>
> i have tested all this stuff and somehow convinced about them....but
> welcome for any comments
>
>
>
> -----Original Message-----
> From: Mas Kato [SMTP:tealp729@home.com]
> Sent: Saturday, May 12, 2001 5:58 PM
> To: 'Mohamed Heeba'; 'CCIELAB'
> Subject: RE: OSPF summary-address--The beat goes on...
>
> Mohamed,
>
> So, redistributing the /24 IGRP subnets into OSPF allows
> 'summary-address' to install the /24 null0 routes for the directly
> connected /28 subnets of the same major net...
>
> I guess to get this hack to work while maintaining control over which
> routes to believe in which routing domain, it looks like we -do- need to
> feed-back the routes, but make them less administratively favorable
> (instead of unreachable) compared to the native OSPF routes. Back to
> redistribution 101...
>
> To answer your question, I don't think filtering is needed with a single
> point of mutual redistribution as long as split horizon is preventing
> routes from being fed-back from the DV-side. But see? I couldn't answer
> your question without a caveat.
>
> I've come to appreciate that understanding these kinds of subtleties is
> the essence of being a CCIE. And this is just one small topic among so
> many...
>
> Regards,
>
> Mas
>
> -----Original Message-----
> From: Mohamed Heeba [mailto:MAHeeba@itqan.co.ae]
> Sent: Saturday, May 12, 2001 12:10 AM
> To: 'Mas Kato'; 'CCIELAB'
> Subject: RE: OSPF summary-address--The beat goes on...
>
>
> HI mas ;
> let me have some share here ..im also running on the summary-address
> command
> torture over here
> my notes about this command is ,it do install the null0 static route in
> the
> routing table BUT this will not happen before you do something like
> "redist
> igrp 1 SUBNETS" ..even when u do "redist igrp 1" only this null0 will
> not
> appear in the routing table ..aslo it will not affected by redist in the
> other direction.ie without doing mutual redistribution .
> feel that the OSPF will propagate this command only when it has external
> routes redist INTO it.
>
> now i have a question here ,DO we really need to put filters if we have
> only
> one point of redistribution and we are doing mutual redist....OR it is
> only
> needed when we have TWO points of redistribution
>
> thx
>
>
> > -----Original Message-----
> > From: Mas Kato [SMTP:tealp729@home.com]
> > Sent: Friday, May 11, 2001 3:11 PM
> > To: 'CCIELAB'
> > Subject: OSPF summary-address--The beat goes on...
> >
> > (edited)
> >
> > Manuel,
> >
> > Thank you! Now we're getting somewhere! But the plot thickens...
> >
> > I back-dated my lab to 12.0(17) and pasted in your config.
> >
> > Here's the view from R2:
> >
> > 172.16.0.0/16 is variably subnetted, 7 subnets, 3 masks
> > C 172.16.4.0/24 is directly connected, Serial0/0
> > I 172.16.5.0/24 [100/8976] via 172.16.4.2, 00:00:33, Serial0/0
> > O 172.16.1.1/32 [110/65] via 172.16.2.1, 00:02:57, Serial0/3
> > O 172.16.2.0/24 is a summary, 00:03:22, Null0
> > C 172.16.2.0/28 is directly connected, Serial0/3
> > O 172.16.3.0/24 is a summary, 00:03:22, Null0
> > C 172.16.3.0/28 is directly connected, Loopback0
> > R1-2#sh ip ospf summ
> >
> > OSPF Process 2, Summary-address
> >
> > 172.16.1.0/255.255.255.0 Metric 16777215, Type 0, Tag 0
> > 172.16.2.0/255.255.255.0 Metric 20, Type 2, Tag 0
> > 172.16.3.0/255.255.255.0 Metric 20, Type 2, Tag 0
> > ...
> >
> > As you can see, the loopback route from R1 didn't make it.
> >
> > But you've led me on to something. I'm wary of doing mutual
> > redistribution without some form of filtering:
> >
> > router ospf 2
> > redistribute igrp 10 subnets route-map IGRP2OSPF
> > !
> > access-list 1 permit 172.16.4.0 0.0.0.255
> > access-list 1 permit 172.16.5.0 0.0.0.255
> > route-map IGRP2OSPF permit 10
> > match ip address 1
> > !
> >
> > 172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
> > C 172.16.4.0/24 is directly connected, Serial0/0
> > I 172.16.5.0/24 [100/8976] via 172.16.4.2, 00:00:04, Serial0/0
> > O 172.16.1.0/28 [110/65] via 172.16.2.1, 00:11:36, Serial0/3
> > C 172.16.2.0/28 is directly connected, Serial0/3
> > C 172.16.3.0/28 is directly connected, Loopback0
> > R1-2#
> > R1-2#sh ip ospf summ
> >
> > OSPF Process 2, Summary-address
> >
> > 172.16.1.0/255.255.255.0 Metric 16777215, Type 0, Tag 0
> > 172.16.2.0/255.255.255.0 Metric 16777215, Type 0, Tag 0
> > 172.16.3.0/255.255.255.0 Metric 16777215, Type 0, Tag 0
> > R1-2#
> > ...
> >
> > So! It must have something to do with my filtering. But what I don't
> > understand is, the routes I'm filtering originate in OSPF... Perhaps
> it
> > has something to do with the classful summary presented to IGRP for
> > those routes?
> >
> > I'm going to do some further testing...
> >
> > Best regards,
> >
> > Mas Kato
> >
> >
> > -----Original Message-----
> > From: Manuel Ratnakumar [mailto:manuelr@cisco.com]
> > Sent: Thursday, May 10, 2001 6:57 PM
> > To: KATO,MAS (HP-USA,ex3)
> > Cc: Attachment
> > Subject: B382815
> >
> >
> > Hi Mas,
> > Guess what? The command summary address also works for out ospf. The
> > behaviour changes when you put the default metric while redistributing
> > ospf
> > into igrp. Please refer to the configuration that i have attached for
> > more
> > details.
> > Please disregard my previous email explanation about the working of
> > summary
> > address command out ospf.
> > Email me if you want to discsus further on this.
> > Thanks and Best Regards
> > Manuel Ratnakumar
> >
> > -----Original Message-----
> > From: KATO,MAS (HP-USA,ex3)
> > Sent: Friday, 11 May 2001 6:02 AM
> > To: Manuel Ratnakumar
> > Subject: RE: B382815
> >
> >
> > Manuel,
> >
> > So the summary route to null0 -did- install into the routing table?
> > Interesting... I've never even seen that. What did 'show ip ospf
> > summary'
> > indicate for the summary metrics? Also, just out of curiosity, what
> > default
> > metric did you use when redistributing into IGRP?
> >
> > Thanks,
> >
> > Mas Kato
> >
> > -----Original Message-----
> > From: Manuel Ratnakumar [mailto:manuelr@cisco.com]
> > Sent: Wednesday, May 09, 2001 11:06 PM
> > To: KATO,MAS (HP-USA,ex3)
> > Cc: Attachment
> > Subject: B382815
> >
> >
> > Mas,
> > I have tested the ospf summary command.
> > I have used 11.2.26 and when you summarise the ospf routes into /24 it
> > does
> > install the route as ospf summary pointing to the null interface but
> > when
> > the redistribution happens the igrp process treats those routes as
> > inaccessible and with metric 4294967295. See below for the debug igrp
> > transaction.
> >
> > 02:25:17: IGRP: received update from 172.16.4.2 on Serial1
> > 02:25:17: subnet 172.16.5.0, metric 8976 (neighbor 501)
> > 02:25:33: IGRP: sending update to 255.255.255.255 via Loopback0
> > (172.16.3.1)
> > 02:25:33: subnet 172.16.2.0, metric=8476
> > 02:25:33: IGRP: sending update to 255.255.255.255 via Serial1
> > (172.16.4.1)
> > 02:25:33: subnet 172.16.1.0, metric=4294967295
> > 02:25:33: subnet 172.16.2.0, metric=4294967295
> > 02:25:33: subnet 172.16.3.0, metric=4294967295
> >
> > So the R3 router will not know any routes from the ospf side (/28).
> > I have also tried the right way which is, installing a static route
> for
> > those summary networks and redistributing static on igrp. It works
> fine.
> >
> > 01:35:29: IGRP: sending update to 255.255.255.255 via Loopback0
> > (172.16.3.1)
> > 01:35:29: subnet 172.16.2.0, metric=8476
> > 01:35:29: IGRP: sending update to 255.255.255.255 via Serial1
> > (172.16.4.1)
> > 01:35:29: subnet 172.16.1.0, metric=1
> > 01:35:29: subnet 172.16.2.0, metric=4294967295
> > 01:35:29: subnet 172.16.3.0, metric=4294967295
> > 01:35:35: IGRP: received update from 172.16.4.2 on Serial1
> > 01:35:35: subnet 172.16.5.0, metric 8976 (neighbor 501)
> >
> > ***** See network 172.16.1.0 ************
> >
> > I hope this results will clear all the doubts you had with summary
> > address
> > command.
> >
> > Is there anything else you want me to do. Feel free to call me or
> email
> > me
> > for any further assistance..
> > Thanks and Regards
> > Manuel Ratnakumar
> >
> > -----Original Message-----
> > From: KATO,MAS (HP-USA,ex3)
> > Sent: Tuesday, 8 May 2001 4:20 PM
> > To: Manuel Ratnakumar
> > Subject: RE: Case B382815 - *NSA*ETAC: Redistributing OSPF into
> Classful
> > Routing Protocols
> >
> >
> > Manuel,
> >
> > Yes, please. In fact, why not just test the oldest IOS still in GD.
> >
> > Here's a simple scenario:
> >
> > Major net is 172.16.0.0
> >
> > (R1)--OSPF/28--(R2)--IGRP/24--(R3)
> >
> > IGRP is passive on the R2's OSPF interface.
> >
> > A lot of people swear up and down that configuring a /24
> > 'summary-address'
> > for the /28 network under the OSPF process on R2 will install a null0
> > route
> > for the summary that will subsequently propagate to R3.
> >
> > When I try it with 12.0 and 12.1, 'show ip ospf summary' on R2 shows
> the
> > summary with a very high metric and the null0 route is -not-
> installed,
> > so
> > the route, of course, never makes it to R3.
> >
> > Thanks very much, I really appreciate it.
> >
> > Regards,
> >
> > Mas Kato
> >
> > -----Original Message-----
> > From: Manuel Ratnakumar [mailto:manuelr@cisco.com]
> > Sent: Saturday, May 05, 2001 5:40 PM
> > To: KATO,MAS (HP-USA,ex3)
> > Subject: RE: Case B382815 - *NSA*ETAC: Redistributing OSPF into
> Classful
> > Routing Protocols
> >
> >
> > Mas,
> > Yes 11.2 is still in GD. Do you want me to test it for you ?
> > Thanks and have a Great Week
> > Manuel
> > **Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
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