Overview

A port channel, also referred to as a Link Aggregation Group (LAG), per IEEE 802.3ad, is a mechanism for combining the bandwidth of multiple physical ports in a switch into one logical link.

Treat a port channel as if it were an individual port: It can be configured as a Layer 2 or Layer 3 interface, as a tagged or untagged member of a VLAN, etc.

In contrast, the interfaces that comprise the port channel must have a minimal configuration. Only the following commands can be configured on an interface if it is a member of a port channel:

• description
• shutdown/no shutdown
• mtu
• ip mtu

The Link Aggregation Control Protocol (LACP) is defined in the IEEE 802.3ad standard and provides a way for two systems to automatically establish and maintain LAGs. 

When configuring port channels, note the following important points:

• LACP does not interoperate with Cisco System’s proprietary port aggregation protocol (PAgP) or Fast Etherchannel (FEC).

• Other vendors refer to the port channel concept with many other terms, such as EtherChannel, Ethernet trunk, and "port teaming".

Configuring Port Channels in SFTOS 2.5

Step 1: Create the port channel.

Starting with SFTOS 2.5, up to 48 port channels, with numbering between 1-128, may be created. Up to six can be dynamic LAGs. Each port channel can have up to eight members.

Unlike previous versions, SFTOS now references port channels by their port channel number, rather than a name, but you can also add a description with the description command, invoked from Interface Port Channel Config mode.

Note: Older configurations that are upgraded to SFTOS 2.5 will have a port channel number automatically created, and the name previously used will become a description under that port channel

Force10(Config)#interface port-channel 1
Force10(conf-if-po-1)#description "line to vegas"

Step 2: Enable the port channel.

Note: It is not possible to add interfaces to a port channel that is not enabled.

Force10(conf-if-po-1)#no shutdown

Note: You can globally enable (or disable) all port channels with the command [no] port-channel enable all.

Step 3: (Optional) Set the mode to static.

Note: By default in SFTOS, port channels are dynamic, which means they use Link Aggregation Control Protocol (LACP), to automatically negotiate port channel connections with similarly configured ports on adjacent machines. The type of connection must be the same on any two connected switches. If you wish to use LACP and are connecting to ports on an adjacent S-Series or other machine that is running LACP, this step should be skipped.

Force10(conf-if-po-1)#protocol static

Step 4: Add member interfaces,

Force10(conf-if-po-1)#channel-member 1/0/33
Force10(conf-if-po-1)#channel-member 1/0/34
Force10(conf-if-po-1)#channel-member 1/0/35

Example of a dynamic LAG

Example of a Static LAG

Configuring Port Channels in SFTOS 2.4 or earlier

Step 1: Determine whether you will create dynamic LAGs or static LAGs.

A dynamic port channel uses special LACP control frames, or protocol data units (PDUs), to negotiate and communicate port information and port channel membership status with the remote network device. A static port channel does not use LACP and essentially forces the ports to join a port channel.

Step 2: Create the port channel and give it a name.

Issue the following commands to create and verify a dynamic port channel using the SFTOS CLI:
Note: In this example, we have created a new port channel named 'newlag'

Force10(Config)#port-channel newlag

Force10(Config)#exit

Step 3: Determine the logical interface number.

Issue the show port-channel all command to determine the logical interface ID assigned by SFTOS automatically to the port channel. 

Force10#show port-channel all

        Port-                Link

Log.    Channel        Adm.  Trap  STP                Mbr     Port   Port

Intf    Name     Link  Mode  Mode  Mode  Type   Ports   Speed  Active

------ --------------- ----- ----  ----  ------ ------- ------ --------

0/1/2  newlag    Down  En.   En.   En.   Dynamic 

!— SFTOS assigned a logical interface number of 0/1/2.

!- Ensure "Adm. Mode" is set to "En." or enable. 

Step 4: Administratively enable the port channel.

Ensure that the "Adm. Mode" or administrative mode is set to "En." or enabled. If the administrative mode is set to disable ("Dis."), use the following command to enable it, depending on your SFTOS version.

Force10#configure
!-- Enter Global Config mode 
Force10(Config)#port-channel enable all
!--The option all enables every configured port-channel.

Force10#configure

!-- Enter Global Config mode 
Force10(Config)#port-channel adminmode all
!-- The option all enables every configured port-channel.

Note: Individual port channel interfaces can be enabled or disabled in Interface Port Channel Config mode for the logical interface. For example, for the port channel in the above example, enter interface 0/1/2 in Config mode to go to Interface Config mode.

Step 5: Add physical ports to the port channel.

Add physical ports as members to the port channel (in this example, the port channel ID is 0/1/2) using the addport command.

Force10#configure

Force10(Config)#interface 1/0/35

Force10(Interface 1/0/35)#addport 0/1/2

Force10(Interface 1/0/35)# exit

Force10(Config)#interface 1/0/36

Force10(Interface 1/0/35)#addport 0/1/2

Force10(Interface 1/0/35)# exit

Step 6: Verify your configuration.

To verify the configuration, above, use the show port-channel 0/1/2 command.

Force10#show port-channel 0/1/2

        Port-          Link

Log.    Channel  Adm.  Trap  STP                Mbr     Port   Port

Intf    Name     Link  Mode  Mode  Mode  Type   Ports   Speed  Active

------ --------------- ----- ----  ----  ------ ------- ------ --------

0/1/2  newlag    Up    En.    En.  En.  Dynamic 1/0/35  Auto    True

                                                1/0/36  Auto    True

Ensure the Port Active field lists “True” for all the member ports. 

Note: To configure a static port channel, use the port-channel staticcapability command to change the LACP setting globally, and then follow the same commands to create a port channel and add ports to it. 

Note: Creating a Port Channel Between an SFTOS switch and an FTOS switch

By default, SFTOS creates a port channel dynamically, while FTOS creates a port channel statically. When connecting an SFTOS switch to an FTOS switch, ensure that you configure the port-channel staticcapability command on the SFTOS switch. Symptoms of a configuration mismatch include incorrect Layer 2 and Layer 3 forwarding behavior. 

Information to Collect if You Open a TAC Case

If you would like assistance from Force10 Networks after following the steps above, please use the Create Service Request form on the iSupport page and include the following information if available:

• Console captures showing the steps taken
• Output from the show tech-support command to capture the installed hardware and the SFTOS version
• Network diagrams or other descriptions of the network design, including VLAN configurations and IP address ranges