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Defining the Proxy Load-Balancing Algorithm

 

When the QFX Series is configured as an FCoE-FC gateway, it balances the FCoE session load assigned to each NP_Port link between the gateway and the FC switch in the FC SAN to avoid overloading or underutilizing each link. The QFX Series supports three types of load-balancing mechanisms:

  • Simple load balancing—Load balancing is based on the weighted utilization (session load) of the NP_Ports connected to an FC fabric. The session load is the sum of the FLOGI and FDISC sessions on each link. Each new ENode fabric login (FLOGI) or VN_Port fabric discovery (FDISC) session is assigned to the least-loaded link, so an FDISC session initiated by the VN_Port on an ENode might not be assigned to the same link as the parent ENode’s FLOGI session. Simple load balancing is the default algorithm. Simple load balancing is the default load-balancing algorithm. Rebalancing the link load disrupts only selected sessions to minimize the impact (the switch uses an algorithm to log out only the sessions that need to be moved to other links to balance the load when those sessions log in again).

  • ENode-based load balancing—Load balancing is based on the weighted utilization (session load) of the NP_Ports connected to an FC fabric. The session load is the sum of the FLOGI and FDISC sessions on each link. However, when an ENode logs in to the fabric, the switch places all subsequent VN_Port FDISC sessions associated with that ENode on the same link as the ENode FLOGI session, regardless of the link load. New ENode FLOGIs are placed on the least-loaded link. The switch calculates the link load based on the combined total of FLOGIs and FDISCs on each NP_Port link. Rebalancing the link load disrupts all sessions (all sessions log out and then log in again).

  • FLOGI-based load balancing—Load balancing is based on the weighted utilization (session load) of the NP_Ports connected to an FC fabric. The session load is the sum of the FLOGI sessions on each link. FDISC sessions are not counted. When an ENode logs in to the fabric, the switch places all subsequent VN_Port FDISC sessions associated with that ENode on the same link as the ENode FLOGI session, regardless of the link load. New ENode FLOGIs are placed on the least-loaded link. Rebalancing the link load disrupts only selected sessions to minimize the impact (the switch uses an algorithm to log out only the sessions that need to be moved to other links to balance the load when those sessions log in again).

To define the proxy load-balancing algorithm for a proxy fabric on the FCoE-FC gateway, set the algorithm as enode-based, simple, or flogi-based:

  • [edit fc-fabrics fabric-name proxy]

    user@switch# set load-balance-algorithm (enode-based | simple | flogi-based)



    For example, to configure a gateway fabric named san_fab1 to use enode-based load balancing:

    user@switch# set fc-fabrics san_fab1 proxy load-balance-algorithm enode-based