From: Antonio Soares (amsoares@netcabo.pt)
Date: Mon Nov 17 2008 - 14:38:57 ARST
Usually in these type of scenarios there are 3 steps:
1) Adjust the OSPF cost of the interface.
2) Avoid recursive routing.
3) Permit/deny the desired networks.
######################################################################################
Step #1)
######################################################################################
R1#sh ip route ospf
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 21.21.21.2, 00:00:12, Serial1/1
[110/65] via 12.12.12.2, 00:00:12, Serial1/0
20.0.0.0/24 is subnetted, 1 subnets
O 20.20.20.0 [110/65] via 21.21.21.2, 00:00:12, Serial1/1
[110/65] via 12.12.12.2, 00:00:12, Serial1/0
R1#
R1#sh ip ospf int | inc Cost
Process ID 1, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 11111
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
Process ID 1, Router ID 1.1.1.1, Network Type LOOPBACK, Cost: 1
Process ID 1, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 64
Process ID 1, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 64
R1#
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int tu12
R1(config-if)#ip ospf cost 64
R1(config-if)#end
R1#
00:27:58: %SYS-5-CONFIG_I: Configured from console by console
R1#
R1#sh ip route ospf
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 200.0.0.2, 00:00:01, Tunnel12
[110/65] via 21.21.21.2, 00:00:01, Serial1/1
[110/65] via 12.12.12.2, 00:00:01, Serial1/0
20.0.0.0/24 is subnetted, 1 subnets
O 20.20.20.0 [110/65] via 200.0.0.2, 00:00:01, Tunnel12
[110/65] via 21.21.21.2, 00:00:01, Serial1/1
[110/65] via 12.12.12.2, 00:00:01, Serial1/0
R1#
######################################################################################
Step #2)
######################################################################################
R1#
00:28:27: %TUN-5-RECURDOWN: Tunnel12 temporarily disabled due to recursive routing
00:28:28: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel12, changed state to down
00:28:28: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Tunnel12 from FULL to DOWN, Neighbor Down: Interface down or detached
R1#
R1#
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#ip access-list standard no-ospf-recursive-routing
R1(config-std-nacl)# deny 2.2.2.2
R1(config-std-nacl)# permit any
R1(config-std-nacl)#router ospf 1
R1(config-router)#distribute-list no-ospf-recursive-routing in Tunnel12
R1(config-router)#end
R1#
R1#
00:29:24: %SYS-5-CONFIG_I: Configured from console by console
R1#
00:29:38: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel12, changed state to up
R1#
R1#
R1#
00:29:41: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Tunnel12 from LOADING to FULL, Loading Done
R1#sh ip route ospf
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 21.21.21.2, 00:00:04, Serial1/1
[110/65] via 12.12.12.2, 00:00:04, Serial1/0
20.0.0.0/24 is subnetted, 1 subnets
O 20.20.20.0 [110/65] via 200.0.0.2, 00:00:04, Tunnel12
[110/65] via 21.21.21.2, 00:00:04, Serial1/1
[110/65] via 12.12.12.2, 00:00:04, Serial1/0
R1#
######################################################################################
Step #3)
######################################################################################
R1#
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#ip access-list standard only-tunnel-destination
R1(config-std-nacl)# permit 2.2.2.2
R1(config-std-nacl)#
R1(config-std-nacl)#router ospf 1
R1(config-router)# distribute-list only-tunnel-destination in Serial1/0
R1(config-router)# distribute-list only-tunnel-destination in Serial1/1
R1(config-router)#
R1(config-router)#end
R1#
R1#
00:31:23: %SYS-5-CONFIG_I: Configured from console by console
R1#
R1#
R1#sh ip route ospf
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 21.21.21.2, 00:00:11, Serial1/1
[110/65] via 12.12.12.2, 00:00:11, Serial1/0
20.0.0.0/24 is subnetted, 1 subnets
O 20.20.20.0 [110/65] via 200.0.0.2, 00:00:11, Tunnel12
R1#
R1#
Regards,
Antonio Soares, CCIE #18473 (R&S)
amsoares@netcabo.pt
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of GAURAV MADAN
Sent: segunda-feira, 17 de Novembro de 2008 14:14
To: ccie forum
Subject: GRE tunnel : Loop
Hi All
This is 2nd time i am asking related question on this forum .. PLss excuse me for that .. i still couldnt get the concept .
f0/0 f0/0
| |
R1========= Serial========= R2
========= FE =========
1) I want comm between f0/0 of R1 and f0/0 of R2.
2) I want this to go via GRE tunnel . I want to use 1 and only 1 protocol OSPF .
3) Tunnel should be able to sustain failures in one of link between 2 routers.
R1
------
interface Tunnel12
ip address 200.0.0.1 255.0.0.0
keepalive 10 3
tunnel source Loopback0
tunnel destination 2.2.2.2
R2
-----
interface Tunnel12
ip address 200.0.0.2 255.0.0.0
keepalive 10 3
tunnel source Loopback0
tunnel destination 1.1.1.1
I do understand the fact that since I am learning tunn dest via ospf and hence can not establish OSPF adj on tunnel interface .
Having said that what are the options to do this task keeping in mind all above req.
I was able to do this by violating a few req :
[A] I learnt 2.2.2.2 on R1 via rip and 1.1.1.1 on R2 via RIP . Hence OSPF can be est on tunn and hence communication was over OSPF .
PLease suggest
Gaurav Madan.
Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Mon Dec 01 2008 - 08:18:30 ARST