Link Aggregation Control Protocol - HP 438031-B21 - 1:10Gb Ethernet BL-c Switch Application Manual

Link Aggregation Control Protocol

Link Aggregation Control Protocol (LACP) is an IEEE 802.3ad standard for grouping several physical
ports into one logical port (known as a dynamic trunk group or Link Aggregation group) with any device
that supports the standard. Refer to the IEEE 802.3ad-2002 for a full description of the standard.
The 802.3ad standard allows standard Ethernet links to form a single Layer 2 link using the Link
Aggregation Control Protocol (LACP). Link aggregation is a method of grouping physical link segments of
the same media type and speed in full duplex, and treating them as if they were part of a single, logical
link segment. If a link in a LACP trunk group fails, traffic is reassigned dynamically to the remaining link(s)
of the dynamic trunk group.
NOTE:
Currently, LACP implementation does not support the Churn machine, an option used to
detect if the port is operable within a bounded time period between the actor and the partner. Only
the Market Responder is implemented, and there is no marker protocol generator.
A port's Link Aggregation Identifier (LAG ID) determines how the port can be aggregated. The Link
Aggregation ID (LAG ID) is constructed mainly from the system ID and the port's admin key, as follows:
System ID—The system ID is an integer value based on the switch's MAC address and the system
priority assigned in the CLI.
Admin key—A port's admin key is an integer value (1-65535) that you can configure in the CLI.
Each HP 1:10GbE switch port that participates in the same LACP trunk group must have the same
admin key value. The admin key is local significant, which means the partner switch does not need
to use the same admin key value.
For example, consider two switches, an Actor (the HP 1:10GbE switch) and a Partner (another switch), as
shown in the following table:
Actor vs. partner LACP configuration
Table 8
Actor Switch
Port 20 (admin key = 100)
Port 21 (admin key = 100)
Port 22 (admin key = 200)
Port 23 (admin key = 200)
In the configuration shown in the table above, Actor switch ports 20 and 21 aggregate to form an LACP
trunk group with Partner switch ports 1 and 2. At the same time, Actor switch ports 22 and 23 form a
different LACP trunk group with a different partner.
LACP automatically determines which member links can be aggregated and then aggregates them. It
provides for the controlled addition and removal of physical links for the link aggregation.
Partner Switch 1
Port 1 (admin key = 50)
Port 2 (admin key = 50)
Ports and trunking
Partner Switch 2
Port 3 (admin key = 60)
Port 4 (admin key = 60)
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