Trunking, also known as VSAN trunking, is a feature specific to switches in the Cisco MDS 9000 Series. Trunking enables interconnect
ports to transmit and receive frames in more than one VSAN, over the same physical link. E and F ports support trunking.
Port channels aggregate multiple physical ISLs into one logical link with higher bandwidth and port resiliency for both Fibre
Channel and FICON traffic. With this feature, up to 16 expansion ports (E-ports) or trunking E-ports (TE-ports) can be bundled
into a port channel. ISL ports can reside on any switching module, and they do not need a designated primary port. If a port
or a switching module fails, the port channel continues to function properly without requiring fabric reconfiguration.
Cisco NX-OS software uses a protocol to exchange the port channel configuration information between adjacent switches to
simplify the port channel management, including misconfiguration detection and autocreation of port channels among compatible
ISLs. In the autoconfigure mode, ISLs with compatible parameters automatically form channel groups; no manual intervention
is required.
Port channels load balance Fibre Channel traffic using a hash of source FC-ID and destination FC-ID, and optionally the exchange
ID. Load balancing using port channels is performed over both Fibre Channel and FCIP links. Cisco NX-OS software can also
be configured to load balance across multiple same-cost FSPF routes.