H3C S5120-EI Series, Operation Manual

Page: 55 / 1191

1-4
For details about IRF, member devices, intermediate devices, and the LACP MAD mechanism, see
IRF
Configuration
in the
System Volume
.
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
higher the
priority
value, the
higher the
priority.
Marker protocol
During a session, if member ports are added to or removed from a dynamic link aggregation group,,
service traffic will need to be redistributed among all the new member ports of the link aggregation
group. The Marker protocol can be employed to quickly redistribute service traffic within link
aggregation groups and ensure the orderly transmission of data frames. The process is as follows:
z
The device stops transmitting service traffic and starts a timer during which no data frames will be
transmitted on the links.
z
The local end uses the Marker protocol to send a Marker Protocol Data Unit (PDU).
z
When a Marker Response Protocol Data Unit (PDU) is received from the peer or the timer expires,
the device starts to redistribute service traffic on all the new link aggregation member ports in
selected state.
Currently, the S5120-EI series Ethernet switches support returning Marker Response PDUs only after
dynamic link aggregation member ports receive Marker PDUs.
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