04-17-2009 08:57 AM - edited 03-06-2019 05:14 AM
I've configured a L2 etherchannel between two ports on a WS-X6548-GE-TX on a 6509 and two ports on a WS-X6148-GE-45AF on a 6503. Both 6500s are at IOS 12.2(33)SXH4. (This is in a lab which is why I have a mix of chassis and blades.)
I config'd the individual interfaces first as switchports and access vlan 533, then config'd the channel-group which automatically created the port channel. Vlan 533 on each 6500 is configed with a /29 ip subnet. (I will be adding a WAE-7341 device on each 6500 in the same vlan for L2 connectivity, hence the /29). So far so good.
However the port channel on the 6509 is automatically created and config'd as a truck port, whereas the port channel on the 6503 is automatically created and has no trunk config.
And surprisingly the port-channel works and traffic passes between the two 6500s just fine.
Here is the resulting config:
ENGLAB-6509
interface Port-channel3
switchport
switchport access vlan 533
switchport trunk encapsulation dot1q <<-----???
switchport mode access
mls qos trust dscp
!
!
interface GigabitEthernet2/23
switchport
switchport access vlan 533
switchport mode access
speed 100
duplex full
mls qos trust dscp
spanning-tree portfast
channel-group 3 mode desirable
!
interface GigabitEthernet2/24
switchport
switchport access vlan 533
switchport mode access
speed 100
duplex full
mls qos trust dscp
spanning-tree portfast
channel-group 3 mode desirable
ENGLAB-6503
interface Port-channel1
switchport
switchport access vlan 533
switchport mode access
mls qos trust dscp
!
!
interface GigabitEthernet3/24
switchport
switchport access vlan 533
switchport mode access
speed 100
duplex full
mls qos trust dscp
spanning-tree portfast
channel-group 1 mode desirable
!
interface GigabitEthernet3/48
switchport
switchport access vlan 533
switchport mode access
load-interval 30
speed 100
duplex full
mls qos trust dscp
spanning-tree portfast
channel-group 1 mode desirable
If I try to remove the trunk statement from the 6509 to match the port-channel config on the 6503, it complains like:
ENGLAB-6509(config)#int p3
ENGLAB-6509(config-if)#no switchport trunk encapsulation dot1q
Command rejected! GigabitEthernet2/23 in port-channel only support Dot1q Trunk Encapsulation
Any idea why the 6509 port-channel includes the trunk, but the 6503 doesn't and is this a stable configuration?
04-17-2009 09:13 AM
The reason you are seeing that is some of the newer linecards only support dot1q trunks. Therefor you don't need to specify "switchport trunk encapsulation dot1q" on the interface config. I know the WS-X6148-GE-45AF is one of those cards.
HTH,
Mark
04-17-2009 09:21 AM
So, should I add the "switchport trunk encapsulation dot1q" to the port-channel on the 6503 with the 6148 line card, or just keep the config on both 6500s the way it is?
04-17-2009 09:34 AM
You should be fine the way that it is.
Mark
04-17-2009 09:40 AM
Mark
I'm a little confused, doesn't take much :-).
The ports were not configured as trunks ie. they are in switchport mode access so why is it even putting that line "switchport trunk encapsulation dot1q" into the config. I could understand if it was configured as a trunk link but it isn't.
On other switches eg 2960 when there is only one option the command "switchport trunk encap... etc." is simply not available.
Not questioning your answer, just would like a bit more clarification as to what is happening.
Jon
04-17-2009 10:19 AM
Jon,
Good question! As to where the "switchport trunk encapsulation dot1q" came from I would like to know myself. My logic was that since switchport mode access was configured on all the ports he should be fine the way that it is. No trunk should form since it will fall back to the access vlan. Which is why it works.
Mark
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