Switch to switch connectivity

[M Talha]

Dear all,

I ran into a problem where i cant ping my two interconnected switches. i have configured LACP between them, they can see each other using sh cdp neighbours but cant ping each other. Although if i configure normal trunking between them it works fine for some time and then they cant ping it each other. i tried debug ip packet and it shows encapsulation failed message. Both are configured with SVI and are part of same vlan. Need help

Regards,

MT

[nazimkha]

Is the port-channel between them up.
Can you paste the configuration of both switches

[M Talha]

Yes the port-channel shows up and they can see each other as well.

[M Talha]

switch A

int fa0/23 - fa0/24

switchport mode trunk

channel-group 1 mode active

Switch B

int fa0/23 - fa0/24
switchport mode trunk
channel-group 1 mode active

[Leo Laohoo]

Are the two switches Catalyst 2K?  If it's not, then there is a command line missing:  switchport trunk encap dot1q

What happens if you try "mode on" instead of "mode active"?

[S-Lemming]

Make sure the Port-channel interface is configured as a trunk and that the VLAN the switches SVI are configured in is allowed on the trunk.

[M Talha]

Port-channel is configured as trunk and vlan is allowed from both sides.

[nazimkha]

Look for CRC errors under the interface.

Can you put all the configs and output of the following CLI

1. show interface port-channel 1

2. show interface fastethernet 0/23 & 0/24

3.sh ip route