Cisco configuration needed for port-aggregation with Nortel switch


  • Description
    Port aggregation (Etherchannel/PortChannel/Trunk) between Cisco and Nortel switches must use the correct mode on the Cisco switch for reliable operation.
    Note that Nortel calls the "EtherChannel port aggregation" a trunk whereas Cisco uses the trunk definition with 802.1q VLAN tagging.

  • Symptoms
    In certain cases, port aggregation between Cisco and Nortel switches may result in link failures.

  • Cause
    Nortel switch supports the standard EtherChannel and optional LACP protocol whereas Cisco might use a proprietary  protocol.

  • Solution
    Several possibilities exist to configure a link aggregation between a Nortel and Cisco switch.
    1. First (recommended)

      Create a static EtherChannel (Port-Channel mode ON) on a Cisco switch and assign the desired interfaces to the Port-Channel. 
      Create a static Trunk on the Nortel switch and assign the desired interfaces.

      Cisco: router (config) interface Port-Channel 1
                router (config-if) exit
                router (config) interface fastethernet 0/1
                router (config-if) channel-group 1 mode ON
                router (config) interface fastethernet 0/2
                router (config-if) channel-group 1 mode ON

      Nortel:    /cfg/l2/trunk 1
                    ena
                    add Ext1
                    add Ext2

      This simple configuration will create a static link aggregation between most on Cisco and Nortel equipment.
      To verity the Trunk Status:
            Cisco:      show int port-channel 1
            Nortel:      /info/l2/trunk
    2. Second

      Both Cisco and Nortel support the industry standard IEEE 802.3ad (LACP). 
      You can create an LACP aggregation on both sides.  Refer to Nortel’s “Applications Guide” and Cisco’s documentation for configuration details.
    3. Third

      Nortel also allows a manual configuration of all possible parameters creating a link aggregation. 
      This configuration possibility can be useful if supporting older proprietary equipment or simply for optimizing traffic distribution over multiple links.
      When enable, several L2 and L3 values, are taking into account for the hashing algorithm use by the link distribution.

      Nortel:         /cfg/l2/thash

  • VSOS

    N/A


    • This article applies to:
    NG 8000
    This article was previously published as:
    Finjan KB 1337

    Last Modified 3/23/2009.
    https://support.trustwave.com/kb/KnowledgebaseArticle13236.aspx