H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – Link Aggregation
H3C S7500E Series Ethernet Switches Chapter 1 Link Aggregation Overview
1-5
4) As there is a limit on the number of selected ports, not all selected-port candidates
can become selected ports. Before the limit is reached, all the candidates are set
to the selected state. When the limit is reached, the candidates with lower port
numbers are set to the selected state while the other candidates are set to the
unselected state. At the same time, the other system gets aware of the state
change of the ports on the higher priority system and thus sets the state of the
corresponding local ports.
5) Set the selected port with the lowest port number as the master port in the
aggregation group on each system.
III. Port configuration considerations in static aggregation
Like in a manual aggregation group, in a static LACP aggregation group, only ports with
configurations consistent with those of the reference port can become selected. These
configurations include port rate, duplex mode, link state and other basic configurations
described in
Consistency Considerations for Ports in an Aggregation.
You need to maintain the basic configurations of these ports manually to ensure
consistency. As one configuration change may involve multiple ports, this can become
troublesome if you need to do that port by port. As a solution, you may add the ports
into an aggregation port group where you can make configuration for all member ports.
When the configuration of some port in a static aggregation group changes, the system
does not remove the aggregation; instead, it re-sets the selected/unselected state of
the member ports and re-selects a master port.
1.3 Load Sharing in a Link Aggregation Group
Link aggregation groups fall into load sharing aggregation groups and non-load sharing
aggregation groups depending on their support to load sharing.
A load sharing aggregation group can contain at least one selected port but a non-load
sharing aggregation group can contain only one.
Link aggregation groups perform load sharing depending on availability of hardware
resources. When hardware resources are available, link aggregation groups created
containing at least two selected ports perform load sharing, while link aggregation
groups created with only one selected port does not perform load sharing. After
hardware resources become depleted, link aggregation groups created work in
non-load sharing mode.
Load sharing is implemented through the selected ports in an aggregation group.
However, the way of selecting forwarding ports varies by packet type:
z For a Layer-2 unicast packet with a known destination MAC address, if the packet
carries an IP datagram, the switch selects the forwarding port according to the
source IP address and destination IP address; otherwise, the switch selects the