Bandwidth; Latency - Qlogic SANbox 5000 Series Installation Manual

A
3.3.2

Bandwidth

Bandwidth is a measure of the volume of data that can be transmitted at a given
transmission rate. A 1/2/4-Gbps port can transmit or receive at nominal rates of 1-,
2-, or 4-Gbps depending on the device to which it is connected. This corresponds
to full duplex bandwidth values of 212 MB, 424 MB, and 850 MB respectively.
10-Gbps ports transmit at a nominal rate of 10-Gbps which corresponds to a full
duplex bandwidth value of 2550 MB. 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 1-Gbps source ports can transmit
to one 2-Gbps 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 212, 424, 850,
or 2550 megabytes 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.
3.3.3

Latency

Latency is a measure of how fast a frame travels from one port to another. The
factors that affect latency include transmission rate and the source/destination
port relationship as shown in
1 Based on minimum frame size of 36 bytes. Latency increases for larger frame sizes.
59096-04 A
Table
Table 3-3. Port-to-Port Latency
Gbps 1
< 0.6 µsec
1
< 0.5 µsec
2
< 0.4 µsec
4
< 0.4 µsec
10
3-3.
Destination Rate
2
1
< 0.8 µsec < 0.8 µsec
< 0.4 µsec
< 0.4 µsec
< 0.3 µsec < 0.3 µsec
< 0.3 µsec < 0.3 µsec
3 – Planning
Performance
4 10
1
< 0.8 µsec
1
< 0.4 µsec
< 0.3 µsec
< 0.2 µsec
1
1
1
3-5