Configuring Performance Parameters; Configuring Open Trunking - McDATA 316095-B21 - StorageWorks Edge Switch 2/24 User Manual

Configuring Performance Parameters

Configuring Open
Trunking
The following sections describe how to configure performance
parameters:
•

Configuring Open Trunking

•
Configuring Preferred Paths
The Open Trunking page enables you to configure open trunking
settings. OpenTrunking is an optional software feature that is
enabled using a feature key.
The purpose of open trunking is to make efficient use of redundant
interswitch links (ISLs) between neighboring switches by means of
load balancing. ISLs are fiber optic cables that connect ports between
Fibre Channel switches and link these switches into a multiswitch
fabric. Fibre Channel traffic flows through these ISLs from end
devices (servers and storage devices) attached to ports on individual
switches.
When the traffic on a particular port exceeds a specified threshold,
the open trunking functionality routes some of the traffic to another
ISL. This prevents traffic from becoming congested on an ISL. Open
trunking provides automatic, dynamic, statistical traffic load
balancing across ISLs in a fabric environment.
The OpenTrunking feature monitors Fibre Channel data rates
through multiple ISLs, dynamically applies a fibre shortest path first
(FSPF) networking algorithm to calculate the optimum path between
fabric elements, and balances the Fibre Channel traffic load
accordingly. The objective is to make the most efficient possible use
of redundant ISLs between neighboring switches, even if these ISLs
have different bandwidths.
The OpenTrunking feature monitors the average data rates of all
traffic flows, from a transmit port to a destination domain. It
periodically adjusts routing tables to reroute data flows from
congested links to lightly loaded links and optimize bandwidth use.
Load balancing among the ISLs does not require user configuration,
other than enabling open trunking and selecting optional or default
settings for congestion thresholds (per port) and a response threshold
for lack of BB_Credits. In particular, you do not need to manually
configure ISLs into trunk groups of redundant links where data can

Configuring Performance Parameters

on page 3-25
on page 3-27
Configuring the Product
3
3-25