Brocade Network OS Administrator’s Guide v4.1.1 - Manual (Page 439)

You can configure a maximum of 24 LAGs with up to 16 links per standard LAG, or four links per
Brocade-proprietary LAG. Each LAG is associated with an aggregator. The aggregator manages the
Ethernet frame collection and distribution functions.
On each port, link aggregation control does the following:
• Maintains configuration information to control port aggregation.
• Exchanges configuration information with other devices to form LAGs.
• Attaches ports to and detaches ports from the aggregator when they join or leave a LAG.
• Enables or disables an aggregator’s frame collection and distribution functions.
Each link in the Brocade VDX hardware can be associated with a LAG; a link cannot be associated with
more than one LAG. The process of adding and removing links to and from a LAG is controlled
statically, dynamically, or through LACP.
Each LAG consists of the following components:
• A MAC address that is different from the MAC addresses of the LAG’s individual member links.
• An interface index for each link to identify the link to neighboring devices.
• An administrative key for each link. Only links having the same administrative key value can be
aggregated into a LAG. On each link configured to use LACP, LACP automatically configures an
administrative key value equal to the port-channel identification number.
Virtual LAGs
Configuring a virtual LAG (vLAG) is similar to configuring a LAG. Once the Brocade VCS Fabric detects
that the LAG configuration spans multiple switches, the LAG automatically becomes a vLAG.
LACP on the Brocade VCS Fabric emulates a single logical switch by sending the same LACP
system ID and sending the same admin and operational key.
Note these vLAG features :
• Only ports with the same speed are aggregated.
• Brocade proprietary LAGs are not available for vLAGs.
• LACP automatically negotiates and forms the vLAG.
• A port-channel interface is created on all the vLAG members.
• The Brocade VCS Fabric relies on you to consistently configure all nodes in the vLAG.
• Similar to static LAGs, vLAGs are not able to detect configuration errors.
• A zero port vLAG is allowed.
• IGMP snooping fits into the primary link of a vLAG to carry multicast traffic.
• Interface statistics are collected and shown per vLAG member switch. The statistics are not
aggregated across switches participating in a vLAG.
• In order to provide link and node level redundancy, the Brocade VCS Fabric supports static vLAGs.
A Brocade VCS Fabric vLAG functions with servers that do not implement LACP because it supports
static vLAGs as well.
Link aggregation setup
The following sections discuss how to set up link aggregation.
Virtual LAGs
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