Lenovo ThinkSystem NE2552E, Application Manual

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© Copyright Lenovo 2018 Chapter 9: Ports and Link Aggregation (LAG)
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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 Link
Aggregation Group) with any device that supports the standard. Please refer to
IEEE 802.3ad ‐ 2002 for a full description of the standard.
IEEE 802.3ad 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 LAG fails, traffic is reassigned dynamically to the remaining link or links of
the dynamic LAG.
The NE2552E supports up to 32 ports in a single LACP LAG. It also supports a total
of 52 LACP LAGs.
Note:
LACP implementation in Lenovo ENOS 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 Marker 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 : 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 NE2552E port that participates in the same LACP
LAG must have the same admin key value. The admin key is locally significant ,
which means the partner switch does not need to use the same admin key value.
For example, consider two switches, an Actor (the NE2552E) and a Partner
(another switch), as shown in Table 17 .
In the configuration shown in Table 17 , Actor switch ports 38 and 39 aggregate to
form an LACP LAG with Partner switch ports 1 and 2. Only ports with the same
LAG ID are aggregated in the LAG. Actor switch port 40 is not aggregated in the
LAG because it has a different LAG ID. Switch ports configured with the same
admin key on the Actor switch but have a different LAG ID (due to Partner switch
admin key configuration or due to partner switch MAC address being different)
can be aggregated in another LAG i.e. Actor switch port 40 can be aggregated in
another LAG with ports that have the same LAG ID as port 40.
Table 17.
Actor vs. Partner LACP configuration
Actor Switch Partner Switch 1
Port 38 (admin key = 100) Port 1 (admin key = 50)
Port 39 (admin key = 100) Port 2 (admin key = 50)
Port 40 (admin key = 100) Port 3 (admin key = 70)