From: smaljure@xxxxxxxxxxxxxxxxx
Date: Mon Sep 25 2000 - 17:00:09 GMT-3
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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