User manual

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McDATA Sphereon™ 4500 Fabric Switch Product Manager User Manual
Optional Features
OpenTrunking
Interswitch links (ISLs) connect ports between E_Ports on Fibre
Channel switches and link these switches into a multiswitch fabric.
Multiple ISLs may be connected between the switches in the fabric.
Data from an attached end device (server or storage) flows through
these ISLs to a target end-device connected to a switch somewhere in
the fabric. A data flow is data received from a specified receive port
that is destined for a port in a specified target domain (switch). The
list of ISLs that are candidates for being rerouted (to or from) is
derived from the fibre shortest path first (FSPF) algorithm.
The OpenTrunking feature monitors the average data rates of all
traffic flows on ISLs (from a receive port to a target domain), and
periodically adjusts routing tables to reroute data flows from
congested links to lightly loaded links and optimize bandwidth use.
The objective of open trunking is to make the most efficient possible
use of redundant ISLs between neighboring switches, even if these
ISLs have different bandwidths.
Load-balancing among the ISLs does not require user configuration,
other than enabling OpenTrunking. However, you can modify
default settings for congestion thresholds (per port) and the Low
BB_Credit Threshold if desired.
In particular, you do not need to manually configure ISLs into “trunk
groups” of redundant links where data can be “off-loaded.”
Candidate links for rerouting flow are identified and maintained
automatically. This means that flow may be rerouted onto a link that
goes to a different adjacent switch, as long as that link is on the least
cost/shortest path to the destination domain ID.
To install and enable this option, select the Configure Feature Key
option under the Product Manager’s Configure menu. Refer to
Configure Feature Key on page 3-17.