11-30
Optimizing Port Usage Through Traffic Control and Port Trunking
Port Trunking
Ports: Traffic Control
and Trunking
Outbound Traffic Distribution Across Trunked Links
All three trunk group options (LACP, Trunk, and FEC) use source-destination
address pairs (SA/DA) for distributing outbound traffic over trunked links.
SA/DA (source address/destination address) causes the switch to distribute
outbound traffic to the links within the trunk group on the basis of source/
destination address pairs. That is, the switch sends traffic from the same
source address to the same destination address through the same trunked link,
and sends traffic from the same source address to a different destination
address through a different link, depending on the rotation of path assign-
ments among the links in the trunk. Likewise, the switch distributes traffic for
the same destination address but from different source addresses through
different links. Because the amount of traffic coming from or going to various
nodes in a network can vary widely, it is possible for one link in a trunk group
to be fully utilized while others in the same trunk have unused bandwidth
capacity even though the address assignments are evenly distributed across
the links in a trunk. In actual networking environments, this is rarely a
problem. However, if it becomes a problem, you can use the HP TopTools for
Hubs & Switches network management software available from Hewlett-
Packard to quickly and easily identify the sources of heavy traffic (top talkers)
and make adjustments to improve performance.
Broadcasts, multicasts, and floods from different source addresses are dis-
tributed evenly across the links. As links are added or deleted, the switch
redistributes traffic across the trunk group. For example, in figure 11-13
showing a three-port trunk, traffic could be assigned as shown in table 11-8.
Interface Option Dynamic LACP
Trunk Group
Static LACP
Trunk Group
Static Non-Protocol
or FEC Trunk Group
Menu Interface No Yes Yes
CLI show trunk No Yes Yes
CLI show interfaces No Yes Yes
CLI show lacp Yes Yes No
CLI show spanning-tree No Yes Yes
CLI show igmp No Yes Yes
CLI show config No Yes Yes