How Can I Use FTOS to Create a Port Channel (LAG)?


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 (if the interface is on a Jumbo-enabled line card and the chassis is in Jumbo mode.)
  • ip mtu (if the interface is on an E-Series jumbo-enabled line card and the chassis is in jumbo mode.)

The Link Aggregation Control Protocol (LACP) is a companion protocol that is also defined in the IEEE 802.3ad standard. LACP 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".

Step 1: Create and enable the port channel.

With FTOS, the number of possible port channels depends on the platform -- up to 52 port channels on the S-Series, 128 on the C-Series, and 255 on the E-Series (TeraScale). Port channel numbering is between 1-128 on S-Series and C-Series, 1-255 on E-Series. Each port channel can have up to eight members.

FTOS references port channels by the port channel number that you assign. You can also add a description with the description command, invoked from INTERFACE PORTCHANNEL mode.

Force10(config)#interface port-channel 1
Force10(config)#no shutdown
Force10(conf-if-po-1)#description "line to vegas"

Step 2: Add member interfaces.

Force10(conf-if-po-1)#channel-member 3/15
Force10(conf-if-po-1)#channel-member 3/16
Force10(conf-if-po-1)#channel-member 4/15

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

Note: By default in FTOS, port channels are static, which means they do not 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 machine that is running LACP, you would set each port to LACP as you configure it:

Force10(conf)#interface Gigabitethernet 3/15
Force10(conf-if-gi-3/15)#no shutdown
Force10(conf-if-gi-3/15)#port-channel-protocol LACP
Force10(conf-if-gi-3/15)#port-channel 32 mode active
Force10(conf)#interface Gigabitethernet 3/16
Force10(conf-if-gi-3/16)#no shutdown
Force10(conf-if-gi-3/16)#port-channel-protocol LACP
Force10(conf-if-gi-3/16)#port-channel 32 mode passive
Force10(conf)#interface Gigabitethernet 4/15
Force10(conf-if-gi-4/15)#no shutdown
Force10(conf-if-gi-4/15)#port-channel-protocol LACP
Force10(conf-if-gi-4/15)#port-channel 32 mode active

Note: Creating Port Channels between SFTOS and FTOS Switches

By default, FTOS creates a port channel statically, while SFTOS creates a port channel dynamically. When connecting an FTOS switch to an SFTOS switch, ensure that both switches are set to configure the port channel links the same way -- either static or dynamic.

Step 6: Verify your configuration.

To verify the configuration, above, you can use the show config command within the INTERFACE mode and within the INTERFACE PORTCHANNEL mode. You can also use the command
show interfaces port-channel [channel-number] [brief].

Force10#show interfaces port-channel 1 brief

LAG Mode Status Uptime Ports
1 L2 up 00:00:08 Gi 3/15 (Up) *
Gi 3/16 (Down)
Gi 4/15 (Up)

Ensure that the ports are listed as "(Up)".

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 FTOS version
  • Network diagrams or other descriptions of the network design, including VLAN configurations and IP address ranges
  How do you rate this document ?
Not Helpful Very Helpful
Comments / Suggestions