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New Member

default route seems not working on my 6500

i have a core and and edge switch both with 2 vlans configured and both running OSPF..

vlanA--vlanB------------vlanC--vlanD---internet

6506 | 3550

OSPF 1 | OSPF 1

Area 4 | area 4

|OSPF 1, Area 4

router 3640

| | |

| | |

| | |

remote sites

ON 6506 MSFC config

interface VlanA

ip address IP_A

!

interface VlanB

ip address IP_B

!

router ospf 1

log-adjacency-changes

network IP_A 0.0.15.255 area 4

network IP_B 0.0.0.255 area 4

!

ip classless

ip route 0.0.0.0 0.0.0.0 IP_C

ON THE SUP ENGINE CONFIG

set interface sc0 vlanA IP_(vlanA_part)

set vlanA

set vlanB

set ip route 0.0.0.0/0.0.0.0 IP_C

NOTE: 1.THE IP_C is on the same subnet of IP_B

2.NO TRUNK ON LINK BET SWITCHES

3.VLANB & VLANC ARE OF DIFF VLAN ID.

observations;

1. intervlan comms is ok

2. no one can go to internet from the core

3. CANT SEE ANY OSPF DERIVED ROUTE

QUESTIONS;

1. IT SEEMS THAT MY DEFAULT ROUTE IS NOT WORKING AT ALL. BUT why. It is clear that i have it in the configuration.

2.Why dont i have ospf derive routes.

anyone could help pls.

10 REPLIES
New Member

Re: default route seems not working on my 6500

I'm not sure I understand this correclty, but here are few things.

When you say intervlan communication works properly, I assume you have ports assigned to these vlans and traffic flows between the machines on different vlans properly.

The IP_C you assigned under the sup for default route should be the IP address of the msfc interface on the vlanA.

In order for OSPF to advertise the default route, you'd need to include "default-information originate"

under ospf process.

If none of this helps, please clarify.

New Member

Re: default route seems not working on my 6500

When you say intervlan communication works properly, I assume you have ports assigned to these vlans and traffic flows between the machines on different vlans properly.

THAT IS RIGHT.

The IP_C you assigned under the sup for default route should be the IP address of the msfc interface on the vlanA.

ARE YOU SAYING ON THE SWITCH CONFIG OR ON THE MSFC CONFIG. I NEED YOUR EXPLANATION ON THIS. IP_C IS THE IP ADDRESS OF THE FAR SWITCH VLAN_C WHICH HAS THE LINK TO MY CORE. YOU MEAN MY DEFAULT ROUTE SHOULD BE THE VLAN ADDRESS OF VlanA?

In order for OSPF to advertise the default route, you'd need to include "default-information originate"

under ospf process.

ITS ONLY MY SWITCH VLANS WHO NEEDS TO KNOW THE DEFAULT ROUTE.

If none of this helps, please clarify

Bronze

Re: default route seems not working on my 6500

If you ping an internet address from the MSFC prompt, does this work ? If it fails, use traceroute and/or an extended ping using the "record" route option to figure out where the failure is occuring.

New Member

Re: default route seems not working on my 6500

hi,

that part works perfectly..i can go anywhere from the msfc prompt. but on the switch prompt, i could go only as far as the vlan where the sc0 belongs.

one thing, tracert to the internet from the workstation on a vlan stops at the vlans ip address. It is not reaching at all the default gateway which is the far end switch.

look, ifeel something wrong with the way i understand about the deafult route on the SWITCH and on the MSFC.

IVE POINTED TO THE SAME FAR END SWITCH..AM NOT SURE ABOUT THIS

New Member

Re: default route seems not working on my 6500

The default route on the switch will be the IP address on the same VLAN on MSFC card. Since you only have 2 vlans, sc0 belongs to vlanA and the IP_C defined on the MSFC belongs to vlanB, your switch default address should point to IP_A address of the MSFC.

What makes no sense here is that a workstastion plugged to either vlanA or vlanB should be able to reach the internet as long as the default gateway on that workstation is configured properly to the IP address of the corresponding vlan interface on the MSFC. The switch's sc0 interface, whether misconfigured or pointing to a wrong default gateway should have no impact at all on your workstations communicating to outside thru the MSFC.

New Member

Re: default route seems not working on my 6500

thats wat puzzles me alot too...dont u think my default gateway is not working fine..i just dont have access to it now, but in the msfc config i captured, i notice that theres no IP ROUTING line..it should have followed the ip subnet zero in some of my readings..dont you think so..i just cant confirm that now..

i am just gathering as much info i can b4 attacking the problem comin few days..what do you think..

thx again

Bronze

Re: default route seems not working on my 6500

One other thing to try is an extended ping from the MSFC, except this time, source the ping from vlan IP_A... and ping IP_C.

This will verify that IP_C knows how to route traffic back to the IP_A network.

You may just be having a routing problem.

New Member

Re: default route seems not working on my 6500

isnt this same as pinging from a host on vlanA?..routing prob? yes, i guess so..but where? am not even expecting my prob will start from this point..

Bronze

Re: default route seems not working on my 6500

if you cannot ping IP_C from vlan A, then the router with IP_C does not know anything about vlan A. You need to somehow make sure that vlan A is known to the router with IP_C and beyond. Are you advertising vlan A out to the internet ? Are you using NAT ?

New Member

Re: default route seems not working on my 6500

IP_C is only 1 of the 3 vlans on a 3550 running ospf..the network statement on the 3550 corresponding to the subnet where IP_C belongs, is also stated on the core switch

on 3550

network vlanC netmask area 4

on core

network vlanB netmask area 4

where lanC = vlanB

it looks like you got me there..it seems like i have to put a static route on 3550 for route on vlanA pointing to IP_B. The network statements on the ospf are not engh right.

correct me if iam wrong.

correct me if iam wrong

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