Configuring Switch Load Sharing - Extreme Networks ExtremeWare XOS Guide Manual

Link Aggregation on the Switch
All ports configured in a LAG begin in an unselected state. Based on the LACPDUs exchanged with the
remote link, those ports that have a matching key are moved into a selected state. If there is no matching
key, the ports in the LAG remain in the unselected state.
However if more ports in the LAG are selected than the aggregator can handle because of the system
hardware, those ports that fall out of the hardware's capability are moved into standby state. As the
name implies, these ports are available to join the aggregator if one of the selected ports should go
offline.
Once the ports in the LAG move into the selected state, LACP uses the mux portion of the protocol to
determine which ports join the aggregator and can collect and distribute traffic. A few seconds after a
port is selected, it moves into the mux state of waiting, and then into the mux state of attached. The
attached ports then send their own LACP sync messages announcing that they are ready to receive
traffic.
The protocol keeps sending and receiving LACPDUs until both sides of the link have echoed back each
other's information; the ends of the link are then considered synchronized. Once the sync messages
match up on each end, that port is moved into the aggregator (into the mux state of collecting-
distributing) and is able to collect and distribute traffic.
The protocol then enables the aggregated link for traffic and monitors the status of the links for changes
that may require reconfiguration. For example, if one of the links in a LAG goes down and there are
standby links in that LAG, LACP automatically moves the standby port into selected mode and that
port begins collecting and distributing traffic.
The marker protocol portion of LACP ensures that all traffic on a link has been received in the order in
which it was sent and is used when links must be dynamically moved between aggregation groups. The
Extreme Networks LACP implementation responds to marker frames but does not initiate these frames.
NOTE
Always verify the LACP configuration by issuing the show ports sharing command; look for the ports listed as being
in the aggregator.

Configuring Switch Load Sharing

To set up a switch for load sharing, or link aggregation, among ports, you must create a load-sharing
group of ports, also known as a link aggregation group (LAG). The first port in the load-sharing group
is configured to be the "master" logical port. This is the reference port used in configuration commands
and serves as the LAG group ID. It can be thought of as the logical port representing the entire port
group.
All the ports in a load-sharing group must have the same exact configuration, including
autonegotiation, duplex setting, ESRP host attach or don't-count, and so on. All the ports in a load-
sharing group must also be of the same bandwidth class.
To define a load-sharing group, or LAG, you assign a group of ports to a single, logical port number. To
enable or disable a load-sharing group, use the following commands:
enable sharing <port> grouping <port_list> {algorithm [port-based | address-based
{L2|L3}]} {lacp}
disable sharing <port>
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ExtremeWare XOS 11.3 Concepts Guide