Default route and Ospf

Answered Question
Dec 21st, 2008

I have a 3745 w/ a NME-16ES-1G-P and have 7 vlans on the NME

and I'm running OSPF on both and I'm able to ping any ip assined to the router but not past that

I'm sure its something simple that I'm just over looking

I've attached the Configs of both the ether switch and the router

I have this problem too.
0 votes
Correct Answer by Harold Ritter about 8 years 4 weeks ago

One more thing. Do not forget to configure "ip nat inside" on interface gig1/0.


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Overall Rating: 4.3 (3 ratings)
Giuseppe Larosa Sun, 12/21/2008 - 13:43

Hello Richard,

to generate a default route that is sent to another OSPF neighbor on the router add

router ospf 1

default-information originate

redistribute static is not enough

Sorry for the other post about IPv6 I didn't realize the module had its own IOS and configuration

Hope to help


is66rlhntadm Sun, 12/21/2008 - 13:49

thats fine

I've added default-information originate and still can't ping z.x.y.38 from the ehterswitch but I can ping it from the router

38 is the ip assigned to my side of the ISP router

also the ehterswitch can't ping (well known any-cast dns server)

Harold Ritter Sun, 12/21/2008 - 13:48


Try assigning the ip address directly under interface Gig1/0/2 rather than under the vlan interface. It should fix the issue.


is66rlhntadm Sun, 12/21/2008 - 13:57

I issued the commands

Int vlan 200

no Ip address

int gi 1/0/2

no switchport

Ip address

Ip ospf 1 area 0

and still can't ping Z.X.Y.38

Giuseppe Larosa Sun, 12/21/2008 - 14:04

Hello Richard,

I don't see any network command in your router ospf processes you need them to build adjacencies

router ospf 1

network area 0

on both sides otherwise the default originate command is useless


I haven't seen you were using the new syntax ignore this post

Hope to help


is66rlhntadm Sun, 12/21/2008 - 14:07

just a little after I started the conversation I changed the commands under ospf 1 to

network area 0

network area 0

network area 0

network area 0

network area 0

network area 0

oh is it better to use range than network?

is66rlhntadm Sun, 12/21/2008 - 14:28

anything else?

the etherswitch still can't reach the internet

I have this feeling that after its sorted that it'll seem so simple and it was just being overlooked

Harold Ritter Sun, 12/21/2008 - 14:55


Can you verify that the ospf adjacency is up between the two devices (show ip ospf nei) and whether you are receiving the default route on the ethernet switch.


Correct Answer
Harold Ritter Sun, 12/21/2008 - 15:54

One more thing. Do not forget to configure "ip nat inside" on interface gig1/0.


is66rlhntadm Sun, 12/21/2008 - 16:09

Entered Show ip ospf Nei on ethSW 1 FULL/DR 00:00:35 GigabitEtherne


Entered Show ip ospf Nei on Router 1 FULL/BDR 00:00:35 GigabitEtherne


and added Ip nat inside to Gi 1/0

is66rlhntadm Sun, 12/21/2008 - 16:14

ok I just tested again from a computer in vlan 2 and it can now ping

but the ethSW still can't

I think at this point I can say its working

Harold Ritter Sun, 12/21/2008 - 17:19


The fact that it doesn't work when you ping from the ethSW is due to the fact that the source address by default is and this address doesn't match any one of your NAT rules. An extended ping with one of the vlans IP address as the source address will solve this issue. This is not a big issue though as long as it works for the vlan users.

Have a great holiday season

is66rlhntadm Sun, 12/21/2008 - 20:14


my intent is so that the managment IP's of devices other than the router don't reach the internet so now that I have it worked out its fine

I could easily set the network in the ACL for the nat trans

the part that fixed hosts in the 3 Internet vlans was the IP nat inside part

thanks for the help and Have a great holiday season as well


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