From: Adam Crisp (adam.crisp@totalise.co.uk)
Date: Fri Oct 11 2002 - 12:50:03 GMT-3
yes,
this is a problem isn't it.
ok I'll, accept that that I am wrong, sorry group/chenyan.
I'm pretty sure I'm right about the AD being involved with the EIGRP/OSPF
example
Maybe it's just a special case with doing multiple redistribitions on the
same router. ??
very puzzled now
Adam
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Carlos G Mendioroz
Sent: 11 October 2002 16:33
To: Adam Crisp
Cc: chenyan; ccielab
Subject: Re: redistribute problem
Adam,
I think the issue has nothing to do with AD.
I have an example:
R1 --- R2 --- R3
R1-R2 are running EIGRP 100 on 192.168.2.0/30
R2-R3 are running OSPF area 0 on 192.168.1.0/30
R3 has a loopback with OSPF area 0 192.168.100.1/24
R2 is redistributing OSPF into EIGRP, config like:
router eigrp 100
redistribute ospf 100
network 192.168.2.0
default-metric 1000 100 200 100 1000
no auto-summary
no eigrp log-neighbor-changes
!
router ospf 100
log-adjacency-changes
network 192.168.1.0 0.0.0.255 area 0
R2 routing:
192.168.1.0/30 is subnetted, 1 subnets
C 192.168.1.0 is directly connected, Serial1/3
192.168.2.0/30 is subnetted, 1 subnets
C 192.168.2.0 is directly connected, Serial1/0
192.168.100.0/32 is subnetted, 1 subnets
O 192.168.100.1 [110/1563] via 192.168.1.2, 00:12:54, Serial1/3
R2 eigrp topo:
P 192.168.100.1/32, 1 successors, FD is 2585600
via Redistributed (2585600/0)
P 192.168.1.0/30, 1 successors, FD is 2585600
via Redistributed (2585600/0)
P 192.168.2.0/30, 1 successors, FD is 20512000
via Connected, Serial1/0
As you can see, EIGRP is taking ALL OSPF networks, even the connected
one from the OSPF redistribution.
The problem changes when you have multiple redistribution. What a
protocol will not redistribute is something that was learnt by
redistribution. (Something like a redistribution split horizon)
HTH
Adam Crisp wrote:
> this is all about Administrative distances and the fact that
redistribution
> between protocols only works if the route makes the Forwarding information
> base.
>
>
> Example
>
> If you have an EIGRP AS, with some external routes, the distance for those
> routes is 170 - an EIGRP external...
>
> If you then have two routers, both running EIGRP and both running OSPF
> Both routers are in the same EIGRP AS and the same OSPF area.
> Both routers are doing mutual redistribution and route maps are in place
to
> prevent routing loops.
> If you then look at the OSPF database, you'll see that only one of the
> Routers is advertiseing the external eigrp routes?
> If you kill the router that is advertising the routes - then the other one
> immediatly start advertising the route.
> Why?
>
> When the 1st router redistributes from EIGRP to OSPF, OSPF then has the
> route - with an external ospf distance of 110 !
> the second router is then presented with two routes to the external, 1 -
> eigrp 170, or ospf 110,
> the ospf route makes the FIB, and that router will not redistribute the
> route!
> When the first router is killed, then the second router has one option -
> eigrp 170, and this route makes the FIB, and this route is then
> redistributed!
>
> Hope this makes sense,
>
> I your example, your router has:
> OSPF - AD 110
> EIGRP - AD 90 (ext 170)
> connected = AD - 0
> ( and static is AD = 1)
>
> when you redistribute the connected into eigrp, the router has two routes
to
> the interface to consider, Eigrp AD-170 and Connected - AD-0
> the connected route makes the FIB.
>
> As the EIGRP route does not make the FIB, then this route will not be
> redistributed into OSPF
>
>
> Good luck
>
> Adam
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> chenyan
> Sent: 11 October 2002 05:06
> To: ccielab
> Subject: redistribute problem
>
>
> hi,all
>
> (eigrp)---R-----(ospf)
> |
> |
> E0
> mutual redistribution is implemended on R between eigrp and ospf,then I
> redistribute connected with E0 into eigrp, is it possible that I cant see
> the connected network in the ospf bacause of the mutual redistribution,
but
> why?
>
> Thanks
>
-- Carlos G Mendioroz <tron@huapi.ba.ar> LW7 EQI Argentina
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