Cisco Nexus 5000 Series Switch CLI Software Configuration Guide, NX-OS 4.0(1a)N1 (OL-16597-01, January 2009)

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Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 36 Configuring SAN Port Channels
Information About SAN Port Channels
• Exchange based—The first frame in an exchange is assigned to a link, and then subsequent frames
in the exchange follow the same link. However, subsequent exchanges can use a different link. This
method provides finer granularity for load balancing while preserving the order of frames for each
exchange.
Figure 36-3 illustrates how flow-based load balancing works. When the first frame in a flow is received
on an interface for forwarding, link 1 is selected. Each subsequent frame in that flow is sent over the
same link. No frame in SID1 and DID1 utilizes link 2.
Figure 36-3 SID1, DID1, and Flow-Based Load Balancing
Figure 36-4 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.
Frame 1
Frame 2
Frame 3
Frame 1
Frame 2
Frame 3
Frame n
Frame 1
Frame 2
Frame 3
Frame n
Frame n
SID1, DID1,
Exchange 1
SID1, DID1,
Exchange 2
SID2, DID2
Exchange 1
Link 1
Link 2
Link 1
Link 2
Link 1
Link 2
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