Cisco MDS 9000 Series Configuration Manual page 240

Configuring PortChannels
Load Balancing
Figure 13: SID1 and DID1-Based Load Balancing
Figure 14: SID1, DID1, and Exchange-Based Load Balancing, on page 223 illustrates how exchange-based
load balancing works. When the first frame in an exchange is received for forwarding on an interface, link 1
is chosen by a hash algorithm. All remaining frames in that particular exchange are sent on the same link. For
exchange 1, no frame uses link 2. For the next exchange, link 2 is chosen by the hash algorithm. Now all
frames in exchange 2 use link 2.
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