From: tom cheung (tkc9789@xxxxxxxxxxx)
Date: Sun Nov 11 2001 - 18:57:37 GMT-3
Albert,
I think this is normal VLSM/FLSM behavior. Since rip is FLSM and does not
include subnet masks in its routing updates, when you redistribute networks
rip has no knowledge about, rip will assume natural network boundary. In
your case, 200.0.0.0 is not in rip's domain, when eigrp redistribute this to
rip, 200.0.0.0/24 will be assumed. If you try to redistribute 172.16.110.0
to rip, 172.16.0.0, and not 172.16.110.0 should show up in rip's routing
table.
Tom
>From: "Albert Lu" <albert_ccie@yahoo.com>
>Reply-To: <albert_ccie@yahoo.com>
>To: "'Ccielab \(E-mail\)'" <ccielab@groupstudy.com>
>CC: <tkc9789@hotmail.com>, "'Ben-Shalom, Omer'" <omer.ben-shalom@intel.com>
>Subject: RE: Weird IGRP and EIGRP Redistribution Findings!!
>Date: Mon, 12 Nov 2001 08:14:51 +1100
>
>I've tried no auto-summary, rebooted and still it keeps doing it.
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Ben-Shalom, Omer
>Sent: Sunday, November 11, 2001 11:17 PM
>To: Albert Lu; 'Ccielab (E-mail)'
>Subject: RE: Weird IGRP and EIGRP Redistribution Findings!!
>
>
>Other people may correct me but on the surface of it you are getting a
>summary route to the classful network 200.0.0.0 , do no auto summary and
>check again.
>
>Omer.
>
>-----Original Message-----
>From: Albert Lu [mailto:albert_ccie@yahoo.com]
>Sent: Sun, November 11, 2001 1:13 PM
>To: 'Ccielab (E-mail)'
>Subject: Weird IGRP and EIGRP Redistribution Findings!!
>
>
>Hi All,
>
>Ok, I've found something really strange redistributing between EIGRP and
>IGRP. From what I know, the FLSM and VLSM redistribution will only
>redistribute routes in the VLSM domain that has the same subnet length as
>the interface of the router connecting the two networks together. For
>instance, if a router that connects IGRP and EIGRP together and they both
>have /24 subnet length, then only the /24 networks in EIGRP (the VLSM) will
>be redistributed into IGRP.
>
>I've encounterd a scenario with two routers, where the border router
>between
>EIGRP and IGRP has a loopback interface of /32 belonging to EIGRP. The
>interfaces in EIGRP and IGRP of the border router is /24, so I would assume
>that any other network that is not a /24 in EIGRP will not be redistributed
>into IGRP.
>
>However, this /32 network is being redistributed into IGRP from EIGRP as a
>/24. So does that mean the redistribution of only /24 networks only apply
>to
>networks that are not directly connected to the border router?
>
>Does this also apply for OSPF and IGRP(or RIP) redistribution?
>
>Take a look at my configs, debugs and routing tables. Basically, it's two
>routers with RA being the border router that has IGRP and EIGRP running on
>it. RB has only IGRP running on it.
>
>The 200.0.0.2/32 loopback interface belongs to the EIGRP process, however
>after the redistribution in IGRP process on the same router, it is sent out
>to RB as 200.0.0.0/24.
>
>Please comment and help!! =)
>
>Thanks
>
>Albert
>
>
>RA
>------
>hostname RA
>!
>ip subnet-zero
>!
>interface Loopback0
> ip address 10.2.17.1 255.255.255.0
> no ip directed-broadcast
>!
>interface Loopback10
> ip address 200.0.0.2 255.255.255.255 <-------***** This has a mask of /32
> no ip directed-broadcast
>!
>interface Serial0
> ip address 10.1.1.1 255.255.255.0
> no ip directed-broadcast
> clockrate 64000
>!
>interface Serial1
> ip address 10.2.2.1 255.255.255.0
> no ip directed-broadcast
> clockrate 64000
>!
>router eigrp 50
> passive-interface Loopback10
> network 200.0.0.0 <-----------******* Network
>200.0.0.2/32 part of EIGRP, not IGRP
>!
>router igrp 100
> redistribute eigrp 50 metric 1000 100 255 1 1500
> passive-interface Loopback0
> passive-interface Serial0
> network 10.0.0.0
>!
>no ip classless
>!
>
>RC
>-------
>hostname RC
>!
>ip subnet-zero
>!
>interface Loopback0
> ip address 10.2.25.2 255.255.255.0
>!
>interface Serial0
> ip address 10.2.2.2 255.255.255.0
>!
>
>router igrp 100
> redistribute connected
> passive-interface Loopback0
> network 10.0.0.0
>!
>ip classless
>!
>
>
>RA Routing Table
>----------------
>04:58:51: IGRP: received update from 10.2.2.2 on Serial1
>04:58:51: subnet 10.2.25.0, metric 8976 (neighbor 501)
>04:59:17: IGRP: sending update to 255.255.255.255 via Serial1 (10.2.2.1)
>04:59:17: subnet 10.1.1.0, metric=8476
>04:59:17: subnet 10.2.17.0, metric=501
>04:59:17: network 200.0.0.0, metric=501
>
>RA#sh ip route
>Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate
>default
> U - per-user static route, o - ODR
>
>Gateway of last resort is not set
>
> 200.0.0.0/32 is subnetted, 1 subnets
>C 200.0.0.2 is directly connected, Loopback10
> 10.0.0.0/24 is subnetted, 4 subnets
>C 10.2.2.0 is directly connected, Serial1
>C 10.1.1.0 is directly connected, Serial0
>I 10.2.25.0 [100/8976] via 10.2.2.2, 00:00:10, Serial1
>C 10.2.17.0 is directly connected, Loopback0
>RA#
>
>RC Routing Table
>----------------
>05:01:02: IGRP: sending update to 255.255.255.255 via Serial0 (10.2.2.2)
>05:01:02: subnet 10.2.25.0, metric=501
>05:01:29: IGRP: received update from 10.2.2.1 on Serial0
>05:01:29: subnet 10.1.1.0, metric 10476 (neighbor 8476)
>05:01:29: subnet 10.2.17.0, metric 8976 (neighbor 501)
>05:01:29: network 200.0.0.0, metric 8976 (neighbor 501)
><--------------****** EIGRP 50 redistributed into IGRP 100
>RC#
>
>RC#sh ip route
>Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
>area
> * - candidate default, U - per-user static route, o - ODR
> P - periodic downloaded static route
>
>Gateway of last resort is not set
>
>I 200.0.0.0/24 [100/8976] via 10.2.2.1, 00:01:19, Serial0
> 10.0.0.0/24 is subnetted, 4 subnets
>I 10.1.1.0 [100/10476] via 10.2.2.1, 00:01:19, Serial0
>C 10.2.2.0 is directly connected, Serial0
>C 10.2.25.0 is directly connected, Loopback0
>I 10.2.17.0 [100/8976] via 10.2.2.1, 00:01:19, Serial0
>RC#
>
>
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