Cisco IOS to CatOS Etherchannel Configuration

Here are the relevant parts of the configuration to setup an etherchannel between an IOS device and a CatOS device. First lets start with the CatOS device, in this case a 6509. We will be using ports 3/9 and 3/10.

We first need to set the ports we want to use to be a trunk. Here we are forcing dot1q.

6509#set trunk 3/1-2 nonegotiate dot1q

Now we need to setup the port channels. These channels will be used as 1 and aggregate bandwidth between them.

6509#set port channel 3/9-10

Note: There is an option at the end of this command to specify the admin group. This is how the CatOS groups the ports. If you do not specify the admin group, the CatOS will automatically assign one. This is something to watch out for if you set each port separately.

Now, turn the port channel on.

6509#set port channel 3/9-10 mode on

That is it for the CatOS. The config for the IOS is quite a bit different. First, create a port channel interface and make it a trunk.

3750(config)#interface port-channel 1
3750(config-if)#switchport trunk encapsulation dot1q
3750(config-if)#switchport mode trunk

Assign ports to the port channel group.

3750(config)#interface GigabitEthernet1/0/1
3750(config-if)#channel-group 1 mode on
3750(config-if)#interface GigabitEthernet1/0/2
3750(config-if)#channel-group 1 mode on

Just connect the ports and everything should come up. To check on the CatOS.

6509#show port channel
Port Status Channel Admin Ch Mode Group Id
—– ———- ——————– —– —–
3/9 connected on 746 1734
3/10 connected on 746 1734

Port Device-ID Port-ID Platform
—– ——————————- ————————- —————-
3/9 3750 GigabitEthernet1/0/1 cisco WS-C3750-48P
3/10 3750 GigabitEthernet1/0/2 cisco WS-C3750-48P

Here, both ports 3/9 and 3/10 show as connected and on the same admin channel.

And for the IOS.

3750#show etherchannel summary
Flags: D – down P – in port-channel
I – stand-alone s – suspended
H – Hot-standby (LACP only)
R – Layer3 S – Layer2
U – in use f – failed to allocate aggregator
u – unsuitable for bundling
w – waiting to be aggregated
d – default port

Number of channel-groups in use: 1
Number of aggregators: 1

Group Port-channel Protocol Ports
——+————-+———–+———————————————–
1 Po1(SU) – Gi1/0/1(P) Gi2/0/1(P)

The last line is the important one. Notice that is shows both ports are in port channel 1.

To configure and IOS to IOS etherchannel, just repeat the exact steps for the IOS on the second switch.
That’s all there is to it.


18 Responses to “Cisco IOS to CatOS Etherchannel Configuration”


  1. 1 Mike May 15th, 2008 at 2:04 pm

    You rock, thanks! Was having trouble until I read this, I was missing the command on the 5500 that aggregated the ports into a single channel.

  2. 2 noobiew Mar 6th, 2009 at 3:12 am

    Hi James,

    I have one question regarding Cisco EtherChannel, let assume i am having a cisco 3750 switch and a cisco 6509 high end switch. Can i create a pair of etherchannel connections between them?

    My concern is because of 3750 switch are running on FastEthernet 100Mb ports, while 6509 switch are running on GigabitEthernet 1000Mb ports. Because i heard it somewhere you need the same speed for the EtherChnnel to be worked.

    So can i create the etherchannel? Or i need to configure the cisco 6509 ports speed settings to auto/100-full deplex to make it work?

    Thank you,

    Have a nice day !

  3. 3 James Mar 6th, 2009 at 8:54 am

    noobiew,

    The difference in port speeds should not be an issue. When you connect the 3750 to the 6509, the 6509 should configure its ports to run at 100Mbps full duplex. You can manually configure the 6509 ports to run at 100Mpbs full duplex, but you should not need to do this.

    Once the connection has been made and the interfaces are up and communicating, you can setup the Etherchannel connection.

    Let me know if you have any more questions.

    James

  4. 4 noobiew Mar 10th, 2009 at 8:00 pm

    Thanks James,

    I can setup the etherchannel connection, and your are right that i no need to manually configure the port speed as default setting for the cisco switches are set to auto negotiation, so as i connect the 3750 to the 6509, i can see the connection are up and the speed settings is set to 100Mbps full duplex (auto negotiation).

    Thank you

    Have a nice day !

  5. 5 Joseph Oct 12th, 2009 at 8:22 am

    Dear James,
    I have got a different situation. Our 6509 gi3/5, gi4/5)connects to 2 different 3750Gs(Sitting very close physically)throgh two fibers.
    We would like to make these ports, part of a port channel for eredundancy,linking the two 3750Gs throgh trunk port.
    Is it possible?
    Can you give some configs please?

    Thanks
    Joseph.

  6. 6 James Oct 13th, 2009 at 1:47 pm

    Joseph,

    Are the 2 3750Gs in a stack configuration, so they are acting like one switch, or are they separate? If they are stacked, you can use the config above.

    Unfortunately, if they are 2 separate switches, you will not be able to do port channel between them unless you run more connections from the 6509 to each 3750G (each 3750G will need 2 cables back to the 6509).

    You can still create the trunk to pass multiple vlans to the 3750Gs though.

    Please let me know if you have any more questions.

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