3Com 4210 PWR, Configuration Manual

Page: 112 / 567

110 C
HAPTER
10: L
INK
A
GGREGATION
C
ONFIGURATION
Port status of dynamic aggregation group
A port in a dynamic aggregation group can be in one of the two states: selected
and unselected.
■
Both the selected and the unselected ports can receive/transmit LACP protocol
packets;
■
The selected ports can receive/transmit user service packets, but the unselected
ports cannot.
■
In a dynamic aggregation group, the selected port with the smallest port
number serves as the master port of the group, and other selected ports serve
as member ports of the group.
There is a limit on the number of selected ports in an aggregation group.
Therefore, if the number of the member ports that can be set as selected ports in
an aggregation group exceeds the maximum number supported by the device, the
system will negotiate with its peer end, to determine the states of the member
ports according to the port IDs of the preferred device (that is, the device with
smaller system ID). The following is the negotiation procedure:
1 Compare device IDs (system pr system MAC address) between the two
parties. First compare the two system priorities, then the two system MAC
addresses if the system priorities are equal. The device with smaller device ID will
be considered as the preferred one.
2 Compare port IDs (port pr port number) on the preferred device. The
comparison between two port IDs is as follows: First compare the two port
priorities, then the two port numbers if the two port priorities are equal; the port
with the smallest port ID is the selected port and the left ports are unselected
ports.
n
For an aggregation group:
■
When the rate or duplex mode of a port in the aggregation group changes,
packet loss may occur on this port;
■
When the rate of a port decreases, if the port belongs to a manual or static
LACP aggregation group, the port will be switched to the unselected state; if
the port belongs to a dynamic LACP aggregation group, deaggregation will
occur on the port.
Aggregation Group
Categories
Depending on whether or not load sharing is implemented, aggregation groups
can be load-sharing or non-load-sharing aggregation groups. When load sharing
is implemented, the system will implement load-sharing based on source MAC
address and destination MAC address.
In general, the system only provides limited load-sharing aggregation resources, so
the system needs to reasonably allocate the resources among different
aggregation groups.
The system always allocates hardware aggregation resources to the aggregation
groups with higher priorities. When load-sharing aggregation resources are used
up by existing aggregation groups, newly-created aggregation groups will be
non-load-sharing ones.