H3C Technologies H3C S5120 Series Switches - Manual (Page 102)

1-4
For details about IRF, member devices, intermediate devices, and the LACP MAD mechanism, see the
operation manuals of IRF-supported devices.
2) LACP priorities
There are two types of LACP priorities: system LACP priority and port LACP priority, as described in
Table 1-3 .
Table 1-3 LACP priorities
Type Description Remarks
System LACP
priority
Used by two peer devices (or systems) to determine which one is
superior in link aggregation.
In dynamic link aggregation, the system that has higher system
LACP priority sets the selected state of member ports on its side first
and then the system that has lower priority sets port state
accordingly.
Port LACP
priority Determines the likelihood of a member port to be selected on a
system. The higher port LACP priority, the higher likelihood.
The
smaller
the
priority
value, the
higher the
priority.
Link aggregation modes
There are two link aggregation modes: dynamic and static. Dynamic link aggregation uses LACP while
static link aggregation does not. A link aggregation group operating in static mode is called a static link
aggregation group, while a link aggregation group operating in dynamic mode is called a dynamic link
aggregation group. Table 1-4 compares the two aggregation modes.
Table 1-4 A comparison between static and dynamic aggregation modes
Aggregation
mode
LACP status
on member
ports
Pros Cons
Static Disabled
Aggregation is stable. The
aggregation state of the member
ports is not affected by their
peers.
The member ports cannot
change their aggregation
state in consistent with their
peers. The administrator
needs to manually maintain
link aggregations.
Dynamic Enabled
The administrator does not need
to maintain link aggregations. The
peer systems maintain the
aggregation state of the member
ports automatically.
The aggregation state of
member ports is easily
affected by the network
environment, which makes
dynamic aggregation
instable.
In a dynamic link aggregation group:
z A selected port can receive and send LACPDUs.
z An unselected port can receive and send LACPDUs only if it is up and have the same class-two
configurations as the aggregate interface.