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. Trunking is supported on E ports
and F ports.
PortChannels 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 PortChannel. ISL ports can reside on any switching module, and they do not need a designated master port. If a port
or a switching module fails, the PortChannel continues to function properly without requiring fabric reconfiguration.
Cisco NX-OS software uses a protocol to exchange PortChannel configuration information between adjacent switches to simplify
PortChannel management, including misconfiguration detection and autocreation of PortChannels among compatible ISLs. In the
autoconfigure mode, ISLs with compatible parameters automatically form channel groups; no manual intervention is required.
PortChannels load balance Fibre Channel traffic using a hash of source FC-ID and destination FC-ID, and optionally the exchange
ID. Load balancing using PortChannels is performed over both Fibre Channel and FCIP links. Cisco NX-OS software also can be
configured to load balance across multiple same-cost FSPF routes.