Performance; Distance - Qlogic SANbox 1400 Series Installation Manual

3 – Planning

Performance

3.3
Performance
The SANbox 1400 Series switch supports class 2 and class 3 Fibre Channel
service with a maximum frame size of 2148 bytes at transmission rates of 1-Gbps,
2-Gbps, or 4-Gbps. A switch port adapts its transmission speed to match that of
the device to which it is connected prior to login when the connected device
powers up. Related performance characteristics include the following:

Distance

Bandwidth
Latency
3.3.1
Distance
Consider the physical distribution of devices and switches in the fabric. Choose
SFP transceivers that are compatible with the cable type, distance, Fibre Channel
revision level, and the device host bus adapter. Refer to
Appendix A Specifications
transceivers.
Each Fibre Channel port is supported by a data buffer with an 8 credit capacity;
that is, 8 maximum sized frames. For fibre optic cables, this enables full
bandwidth over the following approximate distances:
13 kilometers at 1-Gbps (0.6 credits/Km)
6 kilometers at 2-Gbps (1.2 credits/Km)
3 kilometers at 4-Gbps (2.4 credits/km)
Beyond these distances, however, there is some loss of efficiency because the
transmitting port must wait for an acknowledgement before sending the next
frame.
Longer distances can be spanned at full bandwidth by extending credits to
G_Ports, F_Ports, and E_Ports. Each port can donate 7 credits to a pool from
which a recipient port can borrow. The recipient port also loses a credit in the
process. For example, you can configure a recipient port to borrow 7 credits from
one donor port for a total of 14 credits (7+7=14). This will support communication
over the following approximate distances:
23 Km at 1-Gbps (14÷0.6)
11 Km at 2-Gbps (14÷1.2)
5 Km at 4-Gbps (14÷2.4)
You can configure recipient and donor ports using the SANsurfer Switch Manager
application or the Set Config command. Refer to
page B-40
3-4
for more information about cable types and
for more information.
"Set Config Command" on
S
59225-00 B