HP ProCurve Management And Configuration Manual page 310

Port Trunking
Outbound Traffic Distribution Across Trunked Links
12-28
Table 12-6. Example of Link Assignments in a Trunk Group (SA/DA Distribution)
Source: Destination:
Node A Node W
Node B Node X
Node C Node Y
Node D Node Z
Node A Node Y
Node B Node W
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 other links in the same trunk have unused bandwidth capacity
even if the assignments were evenly distributed across the links in a trunk.
Link:
1
2
3
1
2
3