6500 Configuration
interface GigabitEthernet0/25
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 10 mode on (Or desirable)
shut
!
interface GigabitEthernet0/26
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 10 mode on (Or desirable)
shut
interface Port-channel10
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no shut
-------------------------------------------------------------
On the 3750
interface GigabitEthernet1/0/40
description Connected to 6500
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 15 mode (Or desirable)
shut
!
interface GigabitEthernet1/0/41
description Connected to 6500
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 15 mode (Or desirable)
shut
!
interface Port-channel15
switchport trunk encapsulation dot1q
switchport mode trunk
no shut
Based on the port types I assume you had the labels reversed. On Cisco to Cisco links I always use "desirable" versus "on". Although "on" should work.
One the channel is up, all configuration is done on the channel and not on the individual ports. Ecept for a few things like the description. I always configure the port that belong to the channel as shut. I then unshut them with on the port channel.
