Q-Logic ISR6142 manual ISCSI/Gigabit Ethernet Performance, Distance, Bandwidth, Latency

A

3 – Planning iSCSI/Gigabit Ethernet Performance

Distance

Consider the physical distance between Fibre Channel devices. Choose SFP transceivers that are compatible with the cable type and distance you need.

Each Fibre Channel port is supported by a data buffer with a three-credit capacity; that is, three maximum sized frames. For fibre optic cables, this enables full bandwidth over the following approximate distances:

„5 kilometers at 1 Gbps (0.6 credits/Km)

„2.5 kilometers at 2 Gbps (1.2 credits/Km)

Transmitting data beyond these distances reduces efficiency because the transmitting port must wait for an acknowledgement before sending the next frame.

Bandwidth

Bandwidth measures the amount of data transmitted over a channel or network. A 1-Gbps/2-Gbps FC port can transmit or receive at nominal rates of 1- or 2-Gbps, depending on the device to which it is connected. This corresponds to actual bandwidth values of 106 MB and 212 MB, respectively. WAN data rates range from 1.5 Mbps (T1) to greater than 600 Mbps (OC-12).

Latency

Latency measures how long a transaction takes to travel through the router or over a communication link.

iSCSI/Gigabit Ethernet Performance

The iSR6142 router supports Ethernet service at transmission rates of 1000-, 100- or 10-Mbps with a MTU size of 1500 or 9000 (jumbo frames).

NOTE:

An MTU size greater than 1500 should only be used when the router is connected to a 1000 Mbps Ethernet network.

Related performance characteristics include the following:

„Distance

„Bandwidth

„Latency

SN0051102-00 A 3-3