Host FCoE session load balancing differs depending on the version of OS10 that is being used.
OS10 version 10.5.2.4 or later
The FC uplinks from the MX9116n follow industry-standard protocols. Unlike the Ethernet LACP Link Aggregation Group (LAG) protocol, there is no industry-standard mechanism for bonding multiple FC uplinks together. Because of this, Fibre Channel switch manufacturers independently developed their own proprietary mechanisms that are not interoperable. This prevents the MX9116n FC uplinks to be bonded using the native or proprietary protocols.
Instead, load balancing is achieved through a single Fibre Channel Forwarder (FCF) per vFabric. The following describes the behavior of the logical FCF:
- This feature presents all available operational Fibre Channel uplinks in a fabric as a single logical unit. The uplinks are presented as one logical Fibre Channel Forwarder (FCF) to the end points connected to the same fabric.
- Better load balancing is achieved during boot-up and bulk configuration by requiring the FC uplink successfully completed the initial login with the upstream switch at the time of timer expiry. Note: Set timeout value using the CLI command fcoe delay fcf-adv timeout.
- The system finds the optimally loaded FC uplink while the load balancing algorithm makes use of the link's session count and the link speed as factors for session re-balancing.
- End devices do not have control over the link chosen for session establishment. This behavior ensures better load balancing across the available uplinks. After the session is established, the FCoE/FC data traffic is re-directed to the appropriate port to which the login request was associated. Note: As of OME-M 1.20.00 and OS10.5.0.7, it is possible to rebalance FCoE sessions across FCFs. For more information, see Rebalancing FC and FCoE sessions.
OS10 version 10.5.1.9 and earlier
The FC uplinks from the MX9116n follow industry-standard protocols. Unlike the Ethernet LACP Link Aggregation Group (LAG) protocol, there is no industry-standard mechanism for bonding multiple FC uplinks together. Because of this, Fibre Channel switch manufacturers independently developed their own proprietary mechanisms that are not interoperable. This prevents the MX9116n FC uplinks to be bonded using the native or proprietary protocols.
Instead, load balancing rule are used and listed below:
- Load is calculated based on number of server sessions that are connected to the fibre channel forwarder (FCF). The FCF runs in OS10 and provides the FC gateway functionality. There is one FCF for each physical uplink.
- If only one FCF is available, then all the servers form FCoE sessions with that FCF.
- In the case of multiple FCFs, the NPG module running in OS10 will provide the least loaded FCF available at that time to the next server that will log in to the FC fabric.
- Load balancing is performed only during the server login process.
- If a new FCF/uplink is created, existing server sessions will not be automatically balanced across the new session. New server sessions will leverage the new FCF.
- Once a server is logged into an FCF, it will not shift to least loaded FCF until there is a disruption to the existing session. Note: As of OME-M 1.20.00 and OS10.5.0.7, it is possible to rebalance FCoE sessions across FCFs. For more information, see Rebalancing FC and FCoE sessions.