About Load Balancing - Cisco DS-C9216I-K9 Configuration Manual

Chapter 14 Configuring PortChannels

About Load Balancing

Two mechanisms support the load balancing functionality:
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•
Figure 14-3
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 14-3
SID1, DID1,
Exchange 1
SID1, DID1,
Exchange 2
SID2, DID2
Exchange 1
OL-7753-01
Flow based—All frames between source and destination follow the same links for a given flow. That
is, whichever link is selected for the first exchange of the flow is used for all subsequent exchanges.
Exchange based—The first frame in an exchange picks a link and subsequent frames in the exchange
follow the same link. However, subsequent exchanges can use a different link. This provides more
granular load balancing while preserving the order of frames for each exchange.
illustrates how source ID 1 (SID1) and destination ID1-based(DID1) load balancing works.
SID1 and DID1Based Load Balancing
Frame 1
Frame 2
Frame 3
Frame n
Frame 1
Frame 2
Frame 3
Frame n
Frame 1
Frame 2
Frame 3
Frame n
Link 1
Link 2
Link 1
Link 2
Link 1
Link 2
Cisco MDS 9000 Fabric Manager Switch Configuration Guide
About Load Balancing
14-5