From: donny.mateo@xxxxxxxxxxxxxxxxxx
Date: Thu Jun 06 2002 - 03:19:12 GMT-3
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 whe
n
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
I 137.20.100.32/28 [100/10476] via 137.20.200.3, 00:00:15,
Serial1/0
I 137.20.64.0/28 [100/8576] via 137.20.192.1, 00:00:15, Serial1/0
I 200.200.100.0/24 [100/8576] via 137.20.200.17, 00:00:15, Serial1/0
[100/8576] via 137.20.200.1, 00:00:15, Serial1/0
[100/8576] via 137.20.200.3, 00:00:16, Serial1/0
[100/8576] via 137.20.192.1, 00:00:16, Serial1/0
I 14.0.0.0/8 [100/8576] via 137.20.200.17, 00:00:16, Serial1/0
[100/8576] via 137.20.200.1, 00:00:16, Serial1/0
[100/8576] via 137.20.200.3, 00:00:16, Serial1/0
[100/8576] via 137.20.192.1, 00:00:16, Serial1/0
r4#
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