From: paul yang (paulyang@xxxxxxxxx)
Date: Wed Sep 27 2000 - 01:07:51 GMT-3
Tony ,
the problem is R3 will received a summary address form r2 , and if you
clear ip rou * , then the summary router ( to null0 )will not found .
Paul
At 05:27 PM 9/25/00 -0400, you wrote:
>The summary-address command is used in OSPF in this scenario, but it isn't
>for its benefit. It's only to create a route that has the same mask as the
>IGRP enabled interface so that it will receive routes from OSPF with
>variable subnets.
>
>R1----R2----R3
> /26
>
>R1 has network 172.17.59.128/26 and is only running IGRP.
>R2 has networks 172.17.59.0/29, 172.17.59.16/28, 172.17.59.32/27, and
>172.17.59.128/26
>
>On R2 you will use this in OSPF command:
>
>summary-address 172.17.59.0 255.255.255.192
>
>This creates a route on R2 that says 172.17.59.0/26 (note it has the same
>mask as the IGRP router) with next hop Null0. This route will redistribute
>into IGRP because it has the same mask and R1 will get a route that says
>172.17.59.0/26 (which contains all the previous networks except
>172.17.59.128/26) with next hop R2. When R1 sends a packet destined for one
>of those networks off of R2, the routing table on R2 (with more specific
>routes to each network) will route it to the proper destination.
>
>Tony
>
>----- Original Message -----
>From: <smaljure@cibernetworks.com>
>To: <aolzak@buckeye-express.com>; <kbaumgar@cisco.com>
>Cc: <ccielab@groupstudy.com>
>Sent: Monday, September 25, 2000 4:00 PM
>Subject: RE: Redistributing OSPF to IGRP
>
>
>> Hi
>> I also received Kevin's reply on this one...
>> Let us see if I stated myself correctly. I am going to generalize the
>> situation a little to see if we can arrive at a conclusion.
>>
>> R1------R2-----R3
>> /26
>>
>> R1 is running only IGRP.
>> Link between R1 and R2 is a /26
>> R2 is the ASBR running IGRP and OSPF (Redistribution is happening on this
>> box)
>> R3 is running only OSPF
>>
>> Let us say R1 has 5 routes in its table
>>
>> 172.16.1.32/24
>> 172.16.2.32/24
>> 172.16.3.32/24
>> 172.16.4.64/26
>> 172.16.5.64/26
>>
>> When IGRP makes the IGRP update to R2, only two of the above will survive
>> because of IGRP/Classful limitations.... those would be 172.16.4.64/26 and
>> 172.16.5.64/26
>>
>> Now when we redistribute these routes in to OSPF on R2, I would use the
>> summary-address 172.16.0.0 255.255.0.0 within the OSPF process...and hence
>> R3 should receive the 172.16.0.0/16 route.
>>
>> My question is
>>
>> Why should OSPF care how we are summarizing external routes? Isn't the
>> "mask" used with the "summary address.." command supposed to be at the
>> discretion of the administrator?
>>
>> Of course I could be wrong here, would be great if u guys can clarify.
>>
>> Thanks for your time
>>
>> Sanjay
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: Tony Olzak [mailto:aolzak@buckeye-express.com]
>> Sent: Monday, September 25, 2000 3:15 PM
>> To: Maljure, Sanjay; 'Kevin Baumgartner'
>> Cc: ccielab@groupstudy.com
>> Subject: Re: Redistributing OSPF to IGRP
>>
>>
>> It's not incidental. If you use the "summary-address" command and specify
>> the mask as /16, but the same network is /26 on the IGRP router, your
>> network will not redistribute.
>>
>>
>> ----- Original Message -----
>> From: "Maljure, Sanjay" <smaljure@cibernetworks.com>
>> To: "'Kevin Baumgartner'" <kbaumgar@cisco.com>; "Tony Olzak"
>> <aolzak@buckeye-express.com>
>> Cc: <ccielab@groupstudy.com>
>> Sent: Monday, September 25, 2000 1:34 PM
>> Subject: RE: Redistributing OSPF to IGRP
>>
>>
>> > Hi Everyone,
>> > I was just going through this interesting thread and I want to sound u
>> guys
>> > off on what I think...just to confirm if I am right or wrong
>> >
>> > So when we redistribute from OSPF in to IGRP, only the subnets that
>match
>> > the mask on the link in the IGRP domain, will make it to an IGRP router.
>> > This is irrespective of whether we are using the "summary address...."
>> > command when redistributing IGRP in to OSPF. I think it is just
>incidental
>> > that the mask used with the "summary address.." command and the mask on
>> the
>> > link connecting to the IGRP world are the same.
>> >
>> > Is this correct...Please confirm
>> > Thanks
>> > Sanjay
>> >
>> > -----Original Message-----
>> > From: Kevin Baumgartner [mailto:kbaumgar@cisco.com]
>> > Sent: Monday, September 25, 2000 12:44 PM
>> > To: Tony Olzak
>> > Cc: ccielab@groupstudy.com
>> > Subject: Re: Redistributing OSPF to IGRP
>> >
>> >
>> > I tried your setup and used the network that was sent to R2 as
>> > the default-network. It didn't work. Not really suprised as this
>> > is not a classful network.
>> >
>> > But your solution of how to redistribute non-classful (subnetted)
>> > routes into IGRP is very good.
>> >
>> > Kevin
>> >
>> >
>> >
>> > At 12:05 PM 9/25/00 -0400, you wrote:
>> > >Kevin,
>> > >
>> > >Default-network will work also, some scenarios just don't allow that
>> > >command. I figured we better find out how to do it without using static
>> > >routes or the default-network command.
>> > >
>> > >Tony
>> > >
>> > >----- Original Message -----
>> > >From: "Kevin Baumgartner" <kbaumgar@cisco.com>
>> > >To: <aolzak@buckeye-express.com>
>> > >Cc: <ccielab@groupstudy.com>
>> > >Sent: Monday, September 25, 2000 12:09 AM
>> > >Subject: Re: Redistributing OSPF to IGRP
>> > >
>> > >
>> > > > Good catch, I didn't know it would work this way.
>> > > >
>> > > > What about using this as a default-network on R2?
>> > > >
>> > > > Kevin
>> > > >
>> > > > >
>> > > > > This is a multi-part message in MIME format.
>> > > > >
>> > > > > ------=_NextPart_000_01B5_01C02682.08DEFF90
>> > > > > Content-Type: text/plain;
>> > > > > charset="iso-8859-1"
>> > > > > Content-Transfer-Encoding: quoted-printable
>> > > > >
>> > > > > All,
>> > > > >
>> > > > > Just wanted to close this topic and share my findings.
>> > > > >
>> > > > > Without using the default-network command or static routes, the
>only
>> > way
>> > >=
>> > > > > to redistribute OSPF into IGRP with VLSM is to use the
>> summary-address
>> > =
>> > > > > command on the OSPF router. This route will be redistirbuted into
>> IGRP
>> > =
>> > > > > and allow that router to communicate with the other networks. One
>> > catch
>> > >=
>> > > > > is that this summary address must have the same mask as the IGRP
>> link
>> > =
>> > > > > that is enabled on that major network. Example:
>> > > > >
>> > > > > Router 1
>> > > > > !
>> > > > > interface Loopback1
>> > > > > ip address 172.17.59.1 255.255.255.248
>> > > > > !
>> > > > > interface Loopback2
>> > > > > ip address 172.17.59.17 255.255.255.240
>> > > > > !
>> > > > > interface Loopback3
>> > > > > ip address 172.17.59.33 255.255.255.224
>> > > > > !
>> > > > > interface Serial1
>> > > > > ip address 172.17.59.129 255.255.255.192
>> > > > > !
>> > > > > router ospf 100
>> > > > > summary-address 172.17.59.0 255.255.255.192
>> > > > > redistribute igrp 100 metric 64 subnets
>> > > > > passive-interface Serial1
>> > > > > network 172.17.59.0 0.0.0.7 area 0
>> > > > > network 172.17.59.16 0.0.0.15 area 1
>> > > > > network 172.17.59.32 0.0.0.31 area 2
>> > > > > !
>> > > > > router igrp 100
>> > > > > redistribute ospf 100 metric 64 10 255 1 1500
>> > > > > passive-interface Loopback1
>> > > > > passive-interface Loopback2
>> > > > > passive-interface Loopback3
>> > > > > network 172.17.0.0
>> > > > > !
>> > > > > ip classless
>> > > > >
>> > > > >
>> > > > > Router 2
>> > > > > !
>> > > > > interface Ethernet0
>> > > > > ip address 10.0.0.1 255.0.0.0
>> > > > > !
>> > > > > interface Serial0
>> > > > > ip address 172.17.59.130 255.255.255.192
>> > > > > clockrate 64000
>> > > > > !
>> > > > > router igrp 100
>> > > > > network 10.0.0.0
>> > > > > network 172.17.0.0
>> > > > > !
>> > > > > ip classless
>> > > > >
>> > > > > Router 1 and 2 are connected through their serial interfaces. The
>> mask
>> > =
>> > > > > on this connection is /26, so the summary on Router 1 must have a
>> mask
>> > =
>> > > > > of /26 also or it will not redistribute to router 2. At first I
>> tried
>> > a
>> > >=
>> > > > > summary of 172.17.0.0 255.255.0.0 thinking that since IGRP only =
>> > > > > understood classful networks that the summary address would have
>to
>> be
>> > a
>> > >=
>> > > > > class B standard mask. The route did not make it to Router 2.
>After
>> =
>> > > > > skimming through Doyle's book, it reminded me how since the
>> 172.17.0.0
>> > =
>> > > > > network on router 2 had a mask of /26, only matching subnet masks
>> > would
>> > >=
>> > > > > redistribute from router 1.
>> > > > >
>> > > > > Tony
>> > > > >
>> > > > >
>> > > > > ------=_NextPart_000_01B5_01C02682.08DEFF90
>> > > > > Content-Type: text/html;
>> > > > > charset="iso-8859-1"
>> > > > > Content-Transfer-Encoding: quoted-printable
>> > > > >
>> > > > > <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
>> > > > > <HTML><HEAD>
>> > > > > <META content=3D"text/html; charset=3Diso-8859-1" =
>> > > > > http-equiv=3DContent-Type>
>> > > > > <META content=3D"MSHTML 5.00.3018.900" name=3DGENERATOR>
>> > > > > <STYLE></STYLE>
>> > > > > </HEAD>
>> > > > > <BODY bgColor=3D#ffffff>
>> > > > > <DIV><FONT face=3DArial size=3D2>All,</FONT></DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>Just wanted to close this topic
>and
>> =
>> > > > > share my=20
>> > > > > findings.</FONT></DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>Without using the default-network
>=
>> > > > > command or static=20
>> > > > > routes, the only way to redistribute OSPF into IGRP with VLSM is
>to
>> > use
>> > >=
>> > > > > the=20
>> > > > > summary-address command on the OSPF router. This route will be =
>> > > > > redistirbuted=20
>> > > > > into IGRP and allow that router to communicate with the other
>> > networks.
>> > >=
>> > > > > One=20
>> > > > > catch is that this summary address must have the same mask as the
>> IGRP
>> > =
>> > > > > link that=20
>> > > > > is enabled on that major network. Example:</FONT></DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>Router 1</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>!</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>interface Loopback1<BR> ip
>> > address
>> > >=
>> > > > > 172.17.59.1=20
>> > > > > 255.255.255.248<BR>!<BR>interface Loopback2<BR> ip address =
>> > > > > 172.17.59.17=20
>> > > > > 255.255.255.240<BR>!<BR>interface Loopback3<BR> ip address =
>> > > > > 172.17.59.33=20
>> > > > > 255.255.255.224<BR>!</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>interface Serial1<BR> ip
>> address
>> > =
>> > > > > 172.17.59.129=20
>> > > > > 255.255.255.192</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>!</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>router ospf =
>> > > > > 100<BR> summary-address=20
>> > > > > 172.17.59.0 255.255.255.192<BR> redistribute igrp 100 metric
>> > 64=20
>> > > > > subnets<BR> passive-interface Serial1<BR> network
>> > 172.17.59.0
>> > >=
>> > > > > 0.0.0.7=20
>> > > > > area 0<BR> network 172.17.59.16 0.0.0.15 area
>> > 1<BR> network=20
>> > > > > 172.17.59.32 0.0.0.31 area 2</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>!</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>router igrp
>> 100<BR> redistribute
>> > =
>> > > > > ospf 100=20
>> > > > > metric 64 10 255 1 1500<BR> passive-interface=20
>> > > > > Loopback1<BR> passive-interface =
>> > > > > Loopback2<BR> passive-interface=20
>> > > > > Loopback3<BR> network 172.17.0.0<BR>!<BR>ip
>> > classless</FONT></DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>Router 2</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>!</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>interface Ethernet0<BR> ip
>> > address
>> > >=
>> > > > > 10.0.0.1=20
>> > > > > 255.0.0.0<BR> !<BR>interface Serial0<BR> ip address =
>> > > > > 172.17.59.130=20
>> > > > > 255.255.255.192<BR> clockrate 64000</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>!</FONT></DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>router igrp
>100<BR> network=20
>> > > > > 10.0.0.0<BR> network 172.17.0.0<BR>!<BR>ip
>> classless</FONT></DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>Router 1 and 2 are connected
>> through
>> > =
>> > > > > their serial=20
>> > > > > interfaces. The mask on this connection is /26, so the summary on
>> > Router
>> > >=
>> > > > > 1 must=20
>> > > > > have a mask of /26 also or it will not redistribute to router 2.
>At
>> =
>> > > > > first I=20
>> > > > > tried a summary of 172.17.0.0 255.255.0.0 thinking that since IGRP
>> > >only=20
>> > > > > understood classful networks that the summary address would have
>to
>> be
>> > a
>> > >=
>> > > > > class B=20
>> > > > > standard mask. The route did not make it to Router 2. After
>skimming
>> =
>> > > > > through=20
>> > > > > Doyle's book, it reminded me how since the 172.17.0.0 network on
>> > router
>> > >=
>> > > > > 2 had a=20
>> > > > > mask of /26, only matching subnet masks would redistribute from
>> > >router=20
>> > > > > 1.</FONT></DIV>
>> > > > > <DIV> </DIV>
>> > > > > <DIV><FONT face=3DArial size=3D2>Tony</FONT></DIV>
>> > > > > <DIV> </DIV></BODY></HTML>
>> > > > >
>> > > > > ------=_NextPart_000_01B5_01C02682.08DEFF90--
>> > > > >
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