From: Mingzhou Nie (mnie@xxxxxxxxx)
Date: Thu Jun 06 2002 - 09:16:57 GMT-3
Donny,
Now if I only configured secondaries on r5 but only main ip on r4, I
can understand that. In this case, r5 will advertise routers with the
subnet mask defined in secondaries, and r4 will apply ony 28bit mask.
However, I have secondaries configured on r4 also. When r4 receives a
say 20bit route, it should look for its 20bit secondary.
--- donny.mateo@sg.ca-indosuez.com wrote:
>
>
> Hi ,
>
> I suppose the following link would help to explain the behaviour of
> classfull
> routing protocol when receiving route update :
>
> http://www.cisco.com/warp/public/105/54.html
>
> In short, I guess this is what happens.
> You use secondary with all the subnet mask to get the route to be
> advertised to
> R4. Default behaviour of IGRP (and RIP I supposed) is to not
> advertising route
> with the same major network if the mask of the route is not the same
> with the
> mask of the outgoing interface.
>
> Now as R4 received this route, it will do the following ..
> 1. If the route update major network is not the same with the
> interface it's
> receiving the update, summarized it at classfull boundaries
> 2. else (means the same major network), apply the subnetmask of the
> interface
> (which is /28).... also check if there is any bit falls to the host
> portion when
> a applying the mask. If there is make it a host route (/32)
>
> so hence all the /28 network.
>
> Regards
> Donny
>
>
> |--------+------------------------>
> | | Mingzhou Nie |
> | | <mnie@yahoo.co|
> | | m> |
> | | Sent by: |
> | | nobody@groupst|
> | | udy.com |
> | | |
> | | |
> | | 06-06-2002 |
> | | 13:39 |
> | | Please respond|
> | | to Mingzhou |
> | | Nie |
> | | |
> |--------+------------------------>
>
>
>----------------------------------------------------------------------------|
> |
> |
> | To: ccielab@groupstudy.com
> |
> | cc:
> |
> | Subject: igrp/ospf redistribution using secondary
> |
>
>
>----------------------------------------------------------------------------|
>
>
>
>
> Hi, all,
>
> I though I had it working before. Now I'm confused. r5's point to
> point
> subinterface connected to r4. r5's running both protocols and r4 is a
> igrp router. the subnet mask for the link between them is 28bit.
> There
> are 20, 24, 27 and 28 bit networks in r5's routing table learned from
> ospf. I put secondary for all these subnets on both routers and
> redistribute ospf to igrp. r4 does get all routes but the subnet mask
> is all 28bit. Any idea?
>
> (ospf)r5/s0.2 ---igrp--- s0/r4
>
> r5
> interface Serial0.2 point-to-point
> ip address 137.20.200.1 255.255.255.0 secondary
> ip address 137.20.200.3 255.255.255.224 secondary
> ip address 137.20.192.1 255.255.240.0 secondary
> ip address 137.20.200.17 255.255.255.240
> no ip split-horizon
> frame-relay interface-dlci 504
> !
> interface Serial1
> ip address 137.20.25.2 255.255.255.0
> !
> router ospf 1
> log-adjacency-changes
> area 1 virtual-link 137.20.33.33
> area 1 virtual-link 200.200.100.1
> redistribute igrp 1 metric 100 metric-type 1 subnets
> network 137.20.25.2 0.0.0.0 area 2
> network 137.20.64.0 0.0.15.255 area 0
> network 137.20.100.32 0.0.0.31 area 1
> network 137.20.224.5 0.0.0.0 area 0
> distribute-list 1 out igrp 1
> !
> access-list 1 permit 137.20.40.16 0.0.0.15
> access-list 1 permit 137.20.200.16 0.0.0.15
>
> r5#i
> 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
>
> O 200.200.200.0/24 [110/65] via 137.20.25.1, 00:59:51, Serial1
> 137.20.0.0/16 is variably subnetted, 16 subnets, 6 masks
> C 137.20.200.16/28 is directly connected, Serial0.2
> C 137.20.200.0/27 is directly connected, Serial0.2
> C 137.20.200.0/24 is directly connected, Serial0.2
> C 137.20.192.0/20 is directly connected, Serial0.2
> C 137.20.240.0/20 is directly connected, Loopback0
> C 137.20.224.0/20 is directly connected, Dialer1
> O 137.20.30.0/24 [110/70] via 137.20.100.35, 00:40:30,
> Serial0.1
> C 137.20.25.0/24 is directly connected, Serial1
> S 137.20.0.0/16 [1/0] via 137.20.25.0
> O 137.20.60.1/32 [110/11] via 137.20.64.6, 00:38:51, Ethernet0
> I 137.20.40.16/28 [100/8486] via 137.20.200.18, 00:00:32,
> Serial0.2
> O IA 137.20.33.0/24 [110/65] via 137.20.100.35, 00:29:34,
> Serial0.1
> O 137.20.100.33/32 [110/64] via 137.20.100.33, 00:40:30,
> Serial0.1
> C 137.20.100.32/27 is directly connected, Serial0.1
> O 137.20.100.35/32 [110/64] via 137.20.100.35, 00:40:30,
> Serial0.1
> C 137.20.64.0/20 is directly connected, Ethernet0
> O 200.200.100.0/24 [110/65] via 137.20.100.33, 00:40:30, Serial0.1
> 14.0.0.0/24 is subnetted, 1 subnets
> O IA 14.20.2.0 [110/74] via 137.20.100.33, 00:38:51, Serial0.1
> r5#
>
> r4
> interface Serial1/0
> ip address 137.20.200.2 255.255.255.0 secondary
> ip address 137.20.200.4 255.255.255.224 secondary
> ip address 137.20.192.2 255.255.240.0 secondary
> ip address 137.20.200.18 255.255.255.240
> encapsulation frame-relay
> no fair-queue
> serial restart_delay 0
> !
> router igrp 1
> network 137.20.0.0
> !
>
> r4#i
> 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 200.200.200.0/24 [100/8576] via 137.20.200.17, 00:00:14,
> Serial1/0
> [100/8576] via 137.20.200.1, 00:00:14, Serial1/0
> [100/8576] via 137.20.200.3, 00:00:14, Serial1/0
> [100/8576] via 137.20.192.1, 00:00:14, Serial1/0
> 137.20.0.0/16 is variably subnetted, 14 subnets, 4 masks
> C 137.20.200.16/28 is directly connected, Serial1/0
> I 137.20.200.0/28 [100/10476] via 137.20.200.1, 00:00:14,
> Serial1/0
> [100/10476] via 137.20.200.3, 00:00:15,
> Serial1/0
> C 137.20.200.0/27 is directly connected, Serial1/0
> C 137.20.200.0/24 is directly connected, Serial1/0
> I 137.20.192.0/28 [100/10476] via 137.20.192.1, 00:00:15,
> Serial1/0
> C 137.20.192.0/20 is directly connected, Serial1/0
> I 137.20.240.0/28 [100/8976] via 137.20.192.1, 00:00:15,
> Serial1/0
> I 137.20.224.0/28 [100/182571] via 137.20.192.1, 00:00:15,
> Serial1/0
> I 137.20.30.0/28 [100/8576] via 137.20.200.1, 00:00:15,
> Serial1/0
> I 137.20.25.0/28 [100/10476] via 137.20.200.1, 00:00:15,
> Serial1/0
> C 137.20.40.16/28 is directly connected, FastEthernet0/0
> I 137.20.33.0/28 [100/8576] via 137.20.200.1, 00:00:15,
> Serial1/0
>
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