2–Planning
Feature Licensing
59265-02 B 2-5
Latency
Latency is a measure of how fast a frame travels through a switch from one port to
another. The factors that affect latency include transmission rate and the source
and destination port relationship as shown in Table2-4.
Feature LicensingLicense keys provide a way to expand the capabilities of your switch and fabric as
your needs grow. Consider your need for the following features and arrange to
purchase license keys from your switch distributor or authorized reseller:
The Enterprise Fabric Suite license provides access to the Enterprise Fabric
Suite graphical user interface that provides comprehensive fabric
management for fabrics of four or more switches. This license enables you
to download, install, and use Enterprise Fabric Suite on an unlimited number
of workstations. Enterprise Fabric Suite is available with a 30-day trial
license on the CD that is included with the switch product.
The port activation license activates additional SFP ports for a total of 16,
20, or 24 ports.
The 20Gb license enables the XPAK ports to transmit and receive at
25.5Gbps instead of the default 12.75Gbps.
Upgrading a switch is not disruptive, nor does it require a switch reset. To order a
license key, contact your switch distributor or your authorized reseller. For more
information about installing a license key, refer to “Installing Feature License
Keys” on page 3-19.
Table 2-4. Port-to-Port Latency
Destination Rate
Source Rate
Gbps 24810 20
2 < 0.6 µs < 0.7 µs 1
1 Based on minimum frame size of 36 bytes. Latency increases for larger frame sizes.
< 0.6 µs1< 0.6 µs1< 0.6 µs1
4< 0.4 µs < 0.3 µsec < 0.4 µsec1< 0.4 µsec1< 0.3 µsec1
8 < 0.3 µs < 0.2 µs < 0.2 µs < 0.2 µs1< 0.2 µs1
10 < 0.3 µs < 0.3 µs < 0.2 µs < 0.2 µs < 0.2 µs1
20 < 0.3 µs < 0.2 µs < 0.2 µs < 0.2 µs < 0.2 µs