Performance; Distance - Qlogic SANbox 5602 Installation Manual

3 – Planning

Performance

3.3
Performance
The SANbox 5602 switch supports class 2 and class 3 Fibre Channel service at
transmission rates of 1-, 2-, 4-, or 10-Gbps with a maximum frame size of 2148
bytes. A 1-Gbps/2-Gbps 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. 10-Gbps ports transmit at 10-Gbps. 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 a 16 credit capacity;
that is, 16 maximum sized frames. For fibre optic cables, this enables full
bandwidth over the following approximate distances:
26 kilometers at 1-Gbps (0.6 credits/Km)
13 kilometers at 2-Gbps (1.2 credits/Km)
6 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 on 1-Gbps/2-Gbps ports by
extending credits to G_Ports, F_Ports, and E_Ports. Each port can donate 15
credits to a pool from which a recipient port can borrow. However, 1-Gbps/2-Gbps
ports can borrow only from other 1-Gbps/2-Gbps ports. 10-Gbps ports cannot
borrow or donate credits. The recipient port also loses a credit in the process. For
example, you can configure a 1-Gbps/2-Gbps recipient port to borrow 15 credits
from one donor port for a total of 30 credits (15+15=30). This will support
communication over the following approximate distances:
50 Km at 1-Gbps (30÷0.6)
25 Km at 2-Gbps (30÷1.2)
12 km at 4-Gbps (30÷2.4)
3-4
for more information about cable types and
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59096-01 A