Installation guide

2–Planning
Fibre Channel Performance
2-2 ISR651103-00 C
Fibre Channel Performance
The iSR6152 router supports Fibre Channel service at transmission rates of
2Gbps, 4Gbps, or 8Gbps with a maximum frame size of 2,148 bytes. It supports
Ethernet service at transmission rates of 1000Mbps or 100Mbps with a maximum
transmission unit (MTU) size of 1,500 bytes or 9,000 bytes (jumbo frames).
Related performance characteristics include the following:
“Distance” on page 2-2
“Bandwidth” on page 2-2
“Latency” on page 2-3
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, five maximum-sized frames. For fiber optic cables, this enables full
bandwidth over the following approximate distances:
2.5km at 2Gbps (1.2 credits/km)
1.25km at 4Gbps (2.5 credits/km)
0.625km at 8Gbps (5 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
2Gbps, 4Gbps, or 8Gbps Fibre Channel port can transmit or receive at nominal
rates of 2Gbps, 4Gbps, or 8Gbps, depending on the device to which it is
connected. This corresponds to actual bandwidth values of 106MB and 212MB,
respectively. WAN data rates range from 1.5Mbps (T1) to greater than 600Mbps
(OC-12).
NOTE:
An MTU size greater than 1,500 should only be used when the router is
connected to a 1000Mbps Ethernet network and all links (switches, routers,
and so on) that make up the LAN or WAN support greater than 1,500byte
frames and are configured for frames greater than 1,500bytes.