Q-Logic 5800V Manuel D’Utilisation

2–Planning

Performance

2-4

59265-02  B

Extending credits requires a minimum cable length that is dependent on 
transmission speed. Extending credits over short cables can cause excessive port 
resets.

 lists the possible distances and minimum cable lengths for a port 

with 30 credits.

Bandwidth is a measure of the amount of data that can be transmitted at a 
specified transmission rate. An SFP port can transmit or receive at nominal rates 
of 1, 2, 4, or 8Gbps depending on the device to which it is connected. These rates 
correspond to full-duplex bandwidth values of 212MB, 424MB, 850MB, and 
1700MB respectively. XPAK ports transmit at a nominal rate of 10Gbps, which 
corresponds to a full-duplex bandwidth value of 2550MB. With a 20Gbps license 
key, XPAK ports can transmit at a nominal rate of 20Gbps (5100MB bandwidth).

Multiple source ports can transmit to the same destination port if the destination 
bandwidth is greater than or equal to the combined source bandwidth. For 
example, two 2Gbps source ports can transmit to one 4Gbps destination port. 
Similarly, one source port can feed multiple destination ports if the combined 
destination bandwidth is greater than or equal to the source bandwidth.

In multiple chassis fabrics, each link between chassis contributes 424, 850, 1700, 
2550, or 5100MB of bandwidth between those chassis, depending on the speed 
of the link. When additional bandwidth is needed between devices, increase the 
number of links between the connecting switches. The switch guarantees in-order 
delivery with any number of links between chassis.

                                                                                           

1Gbps

50 Km (30÷0.6)

3 Km

2Gbps

25 Km (30÷1.2)

1.5 Km

4Gbps

12 Km (30÷2.4)

0.75 Km

8Gbps

6 Km (30÷4.8)

0.37 Km