Trunks And Portchannels - Cisco MDS 9000 Series Configuration Manual

Interface Overview

Trunks and PortChannels

Trunks and PortChannels
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.
Cisco MDS 9000 Series Interfaces Configuration Guide, Release 8.x
7