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New Member

inter vlan routing and port channels


I need some help clearing up some issues in my mind. We have a couple core switches which our 6509's and distribution switches on all of the floors (either 5500/6500.) Each floor basically has its own vlan along with some third party vlans. The way the routing is set up is this. There are 2 msm's, one on each core 6509. It appears that the routing is done via a port channel. The port channel is associated with each of the vlans. For example vlan 1 is port channel 1.1 and vlan 15 is interface port channel 1.15. If I was going to create a test network with its own vlan and that sort of thing, would I need to create a port channel for this network as well? I was just not sure about this and needed some help. When I did a show config on one of the core switches it seems it auto assigns ports a port channel admin....

Very interesting and thanks for clearing this up...

New Member

Re: inter vlan routing and port channels

If you wanted to communicate between your test network vlan and the other vlans then yes, you would have to create a port channel subinterface similar to the others on the core switch. Once you have configured the vlan on the necessary switches, console to your core switches and create a new subinterface as follows:

(config)interface port-channel 1.x (where x is the new vlan number)

(config-subif)encapsulation isl/dot1q x (using either isl or dot1q encapsultion. All subinterfaces within the port-channel must use the same encapsulation so look at what the others are set to. The x value should represent the vlan number of your test network)

(config-subif)ip address x.x.x.x x.x.x.x (This should be equal to the ip address of the default gateway configured on the workstations within the vlan. This will provide intervlan routing of IP packets!)

Don't worry about the admin group. As far as I'm aware it is only used to show a specific channel when multiple channels exist on a switch. For example, if you have 10 channels configured and only want to see information regarding one of the channels, on a switch you would enter:

show channel group x (where x is the admin group number). You can set the admin group to a value yourself (rather than it being automatically assigned) but spanning tree then has to reconverge leaving users offline for approx 30 seconds.

Hope this helps, let me know how you go on!

New Member

Re: inter vlan routing and port channels

thanks man....I'll try that...