From: Bill Young (byoung@xxxxxxxxxx)
Date: Mon Dec 18 2000 - 10:20:34 GMT-3
Fred (and others),
Can someone refresh my memory as to why we need the neighbor statements in
the FR OSPF config below?
Thanks,
Bill
----- Original Message -----
From: "Fred Ingham" <fningham@worldnet.att.net>
To: "Roy Grego" <ccsi100@yahoo.com>; <ccielab@groupstudy.com>
Sent: Sunday, December 17, 2000 11:23 PM
Subject: Re: Losing routes when OSPF red into IGRP
> Long Answer.
>
> There are some general principles for redistributing VLSM-FLSM:
> RIP will redistribute the 0.0.0.0 default network
> use the default-information originate command
> IGRP does not distribute the 0.0.0.0 network
> use the ip default-network command
> network must be classful, in routing table,
> and not on FLSM router
> Split horizon will effect routes
> ip classless must be configured on the FLSM router.
>
> Sample config OSPF/RIP:
> R1 - router running RIP and OSPF:
>
> int s0/0
> encap frame
> bandwidth 1000
> !
> int s 0/0.1 point-to-multipoint
> description serial to r2 and r3
> ip add 172.16.65.1 255.255.255.128 /25 will not be distributed
> frame map ip 172.16.65.2 102 br to RIP or to IGRP
> frame map ip 172.16.65 3 103 br
> !
> int s 0/0.2 point-to-point
> description serial to r4
> ip add 172.16.33.1 255.255.255.0 /24 in RIP or IGRP domain
> frame-relay interface-dlci 102
> !
> router ospf 1
> redistribute rip subnets
> summary-address 172.16.44.0 255.255.252.0 r4 loopbacks
> netw 172.16.65.0 0.0.0.255 area 0
> neighbor 172.16.65.2 r1 is DR, this is
> neighbor 172.16.65.3 another topic
>
> router rip
> redistribute ospf 1 metric 3 Mutual redistribution
> default-information originate distribute a default route
> passive-interface s0/0.1
> netw 172.16.0.0
>
> Note that route maps or distribute lists are not needed to
> prevent loops. Why?
>
> R4 - router running RIP:
>
> int s 0
> encap frame
> ip add 172.16.33.4 255.255.255.0
> frame map ip 172.16.33.1 401 br
> ip split-horizon off by default, needs to be enabled
> !
> int loop 0
> ip add 172.16.44.4 255.255.255.0
> int loop 1
> ip add 172.16.45.4 255.255.255.0
> int loop 2
> ip add 172.16.46.4 255.255.255.0
> int loop 3
> ip add 172.16.47.4 255.255.255.0
> !
> router rip
> netw 172.16.0.0
>
> ip classless
>
> Discussion: r4 will announce and accept /24 routes. r4 will also
> accept host, /32, routes, and classful routes. r1 will not advertise
> /25 routes to r4. Without split horizon enabled r4 would announce
> routes back to r1. With the default-information-originate there
> will be a default route in r4's route table pointing to r1 s0/0.2.
> The /25 routes will not be in r4's routing table but all interfaces
> will be able to be pinged using the default route.
>
> r4 route table before default-information originate command:
>
> Gateway of last resort is not set
>
> 172.16.0.0/24 is subnetted, 5 subnets
> C 172.16.44.0 is directly connected, Loopback44
> C 172.16.45.0 is directly connected, Loopback45
> C 172.16.46.0 is directly connected, Loopback46
> C 172.16.47.0 is directly connected, Loopback47
> C 172.16.33.0 is directly connected, Serial0
>
> r4 route table after adding default-information originate:
>
> Gateway of last resort is 172.16.33.1 to network 0.0.0.0
>
> 172.16.0.0/24 is subnetted, 5 subnets
> C 172.16.44.0 is directly connected, Loopback44
> C 172.16.45.0 is directly connected, Loopback45
> C 172.16.46.0 is directly connected, Loopback46
> C 172.16.47.0 is directly connected, Loopback47
> C 172.16.33.0 is directly connected, Serial0
> R* 0.0.0.0/0 [120/1] via 172.16.33.1, 00:01:18, Serial0
>
> ***********************************************************
>
> R1 - router running IGRP and OSPF (changes from above only):
>
> int e 0 another network which can be
> ip address 192.168.1.1 255.255.255.0 from ospf or a connected interface
> no keep on r1
>
> router ospf 1
> no redistribute rip subnets
> redistribute igrp 1 subnets
>
> no router rip
>
> router igrp 1
> redistribute ospf 1
> default-metric 1000 2000 255 1 1500
> network 172.16.0.0
> network 192.168.1.0 required since network is not in
> passive-interface s0/0.1 ospf, could also redis connected
>
> ip default-network 192.168.1.0 classful, in r1's routing table,
> not advertised by r4
>
> R4 - router running IGRP (changes only):
>
> no router rip
>
> router igrp 1
> netw 172.16.0.0
>
> Discussion: Same comments as for RIP except now there
> is no default 0.0.0.0 route. r4's routing table will have
> a default gateway pointing to r1's s0/0.2. The /25 networks
> will not be in the routing table but can be pinged using the
> gateway of last resort. ip classless must be configured on r4.
>
> r4's routing table before ip default-network command:
>
> Gateway of last resort is not set
>
> 172.16.0.0/24 is subnetted, 5 subnets
> C 172.16.44.0 is directly connected, Loopback44
> C 172.16.45.0 is directly connected, Loopback45
> C 172.16.46.0 is directly connected, Loopback46
> C 172.16.47.0 is directly connected, Loopback47
> C 172.16.33.0 is directly connected, Serial0
>
> r4's routing table after default network command:
>
> Gateway of last resort is 172.16.33.1 to network 192.168.1.0
>
> 172.16.0.0/24 is subnetted, 5 subnets
> C 172.16.44.0 is directly connected, Loopback44
> C 172.16.45.0 is directly connected, Loopback45
> C 172.16.46.0 is directly connected, Loopback46
> C 172.16.47.0 is directly connected, Loopback47
> C 172.16.33.0 is directly connected, Serial0
> I* 192.168.1.0/24 [100/8576] via 172.16.33.1, 00:00:05, Serial0
>
> HTH to clearify issues. Fred.
>
> Roy Grego wrote:
> >
> > Hello,
> >
> > When I red OSPF routes into IGRP I am losing some
> > routes.
> >
> > Example:
> >
> > OSPF clouds -- R1 --- IGRP ----- R2
> >
> > R1 has these routes in its OSPF database & Routing
> > table. R1 can ping all these addresses.
> > C 1.1.1.1 /24
> > E2 2.2.2.2 /30
> > E2 3.3.3.3 /24
> > C 4.4.4.4 /24
> > O 5.5.5.5 /24
> > O 6.6.6.6 /30
> >
> > BUT R2 will not see 3.3.3.3 or 6.6.6.6. Where do
> > these go? The routes being lost are not all subnetted,
> > nor are they External OSPF routes.
> >
> > Sample configs:
> > router ospf 1
> > network 1.1.1.1 0.0.0.0 area 0
> > red igrp 4 subnets metric 500 route-map IGRP2OSPF
> >
> > router igrp 4
> > network 4.0.0.0
> > red ospf 1 match e i metric 1500 100 255 1 1500
> >
> > Is there a debug to see the routes being redistributed
> > and/or routes rejected for redistribution?
> >
> > FYI, R1 has a Frame connection with Multipoint subint.
> > and networks 3, 5, & 6 can be routed 2 different ways.
> > Does OSPF have a problem with this?
> >
> > Thanks,
> > ROY
> >
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