Enabling Mac Address Table Synchronization For Cross-Card Aggregation - 3Com S7906E Configuration Manual

To do...
Configure the
aggregation group to
work in dynamic
aggregation mode
Exit to system view
Enter Layer 2 Ethernet
interface view
Assign the Ethernet
interface to the
aggregation group
Assign the port a LACP
priority
Removing a dynamic aggregate interface also removes the corresponding aggregation group. At
the same time, the member ports of the aggregation group, if any, leave the aggregation group.
To guarantee a successful dynamic aggregation, ensure that the peer ports of the ports
aggregated at one end are also aggregated. The two ends can automatically negotiate the selected
state of the ports.
When a load-sharing aggregation group becomes a non-load-sharing aggregation group because
of insufficient load sharing resources, one of the following problems may occur: the number of
selected ports of the actor is inconsistent with that of the partner, which may result in incorrect
traffic forwarding; the peer port of a selected port is an unselected one, which may result in
upper-layer protocol and traffic forwarding anomalies. You should fully consider the situation when
making configuration.

Enabling MAC Address Table Synchronization for Cross-Card Aggregation

The S7900E series switches support cross-card link aggregation, namely the member ports of the
aggregation group locate on different cards. One problem with cross-card link aggregation is that the
outgoing port for a packet and the incoming port for the reply to the packet may reside on different cards.
If this occurs, the outgoing port will never learn the source MAC address in the reply packet, and all
subsequent packets to the same destination will be flooded as unknown unicast packets. To improve
forwarding efficiency, an automatic MAC address table synchronization mechanism must be used
between line cards.
For cards of the same type, synchronization is performed automatically and requires no administrative
interference. For link aggregation across different types of cards, however, you may need to enable
Use the command...
link-aggregation mode dynamic
quit
interface interface-type
interface-number
port link-aggregation group
number
lacp port-priority port-priority
1-8
Remarks
Required
By default, an aggregation group
works in static aggregation
mode.
—
Required
Repeat the two steps to assign
multiple Ethernet interfaces to
the aggregation group.
Optional
By default, the LACP priority of a
port is 32768.
Changing the LACP priority of a
port may affect the
selected/unselected state of the
ports in the dynamic aggregation
group.