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smith606306
Beginner

No IP classless

I am having trouble logging into one of my remote switches (SSH2 via TACACS) I can log into a different one succesfully at the same site.

The only difference i can see in the configuration is the one it fails on has the 'no ip classless' line on it.

Would this affect it?

Will it have any immediate impact on the network if i chane it to 'IP classless'?

Switch A

ip default-gateway 10.123.111.78

ip classless

ip route 0.0.0.0 0.0.0.0 10.123.111.78

Switch B

ip default-gateway 10.123.111.78

no ip classless

ip route 0.0.0.0 0.0.0.0 10.123.111.78

2 ACCEPTED SOLUTIONS

Accepted Solutions

Hi Andrew

Are you able to ping the Switch under question of no remote access. I believe you would be not able to ping it either.

From my understanding what is going on here is that due to the "ip classless" command being disabled the routing table on the Switch is acting Classfully and the default-route is not being taken into consideration for reverse routing to the source of Remote Access. Is the source part of  Major Network 10.0.0.0/8 ?

If its so the defaulr route will not be followed because of Classfull routing as there is specific route (

10.123.111.78) for the Major Subnet 10.0.0.0/8 in the routing-table.

You can enable the "ip classless" command and everything will be working fine as the other switch.

Regards

Varma

View solution in original post

Jon Marshall
VIP Community Legend

Andrew

If these are L2 switches ie. no inter-vlan routing then as Reza says simply remove the "ip route 0.0.0.0 ...." statement and then ip classless doesn't come into it.

If these are L3 switches then ip classless could be having an affect although on recent IOS versions you need to have disabled CEF as well for it to take effect.  If they are L3 as Varma suggests then simply remove the "no ip classless"

Jon

View solution in original post

3 REPLIES 3
Reza Sharifi
Hall of Fame Expert

ip classless and no ip classless should not prevent you from login to the switch. 

if your switches are layer-2 only, you only need ip default-gateway, and no need for the default route.

Why do you have both?

HTH

Hi Andrew

Are you able to ping the Switch under question of no remote access. I believe you would be not able to ping it either.

From my understanding what is going on here is that due to the "ip classless" command being disabled the routing table on the Switch is acting Classfully and the default-route is not being taken into consideration for reverse routing to the source of Remote Access. Is the source part of  Major Network 10.0.0.0/8 ?

If its so the defaulr route will not be followed because of Classfull routing as there is specific route (

10.123.111.78) for the Major Subnet 10.0.0.0/8 in the routing-table.

You can enable the "ip classless" command and everything will be working fine as the other switch.

Regards

Varma

View solution in original post

Jon Marshall
VIP Community Legend

Andrew

If these are L2 switches ie. no inter-vlan routing then as Reza says simply remove the "ip route 0.0.0.0 ...." statement and then ip classless doesn't come into it.

If these are L3 switches then ip classless could be having an affect although on recent IOS versions you need to have disabled CEF as well for it to take effect.  If they are L3 as Varma suggests then simply remove the "no ip classless"

Jon

View solution in original post