Cisco Nexus 5000 Series Switch CLI Software Configuration Guide (OL-16597-01, July 2009)

• A SAN port channel enables several physical links to be combined into one aggregated logical link.
• An industry standard E port can link to other vendor switches and is referred to as inter-switch link
(ISL), as shown on the left side of the figure below.
• VSAN trunking enables a link transmitting frames in the EISL format to carry traffic for multiple VSAN
. When trunking is operational on an E port, that E port becomes a TE port. EISLs connects only between
Cisco switches, as shown on the right side of the figure below.
Figure 53: VSAN Trunking Only
You can create a SAN port channel with members that are E ports, as shown on the left side of the figure below.
In this configuration, the port channel implements a logical ISL (carrying traffic for one VSAN).
You can create a SAN port channel with members that are TE-ports, as shown on the right side of the
figure below. In this configuration, the port channel implements a logical EISL (carrying traffic for multiple
VSANs).
Figure 54: Port Channels and VSAN Trunking
Related Topics
• Configuring VSAN Trunking, page 507
Understanding Load Balancing
Load-balancing functionality can be provided using the following methods:
• 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 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.
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
516 OL-16597-01
Configuring SAN Port Channels
Understanding Load Balancing