From: tom cheung (tkc9789@xxxxxxxxxxx)
Date: Sun Nov 11 2001 - 11:53:39 GMT-3
EIGRP has auto-summary on by default. Your 200.0.0.0 was summarized to a
/24 then redistributed to igrp.
>From: "Albert Lu" <albert_ccie@yahoo.com>
>Reply-To: "Albert Lu" <albert_ccie@yahoo.com>
>To: "'Ccielab \(E-mail\)'" <ccielab@groupstudy.com>
>Subject: Weird IGRP and EIGRP Redistribution Findings!!
>Date: Sun, 11 Nov 2001 22:13:24 +1100
>
>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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