Installation guide

2–Planning
GbE Performance
ISR651103-00 C 2-3
Latency
Latency measures how long a transaction takes to travel through the router or
over a communication link.
GbE Performance
The iSR6152 router supports Ethernet service at transmission rates of 1000Mbps
or 100Mbps with a MTU size of 1,500 or 9,000 (jumbo frames).
Consider the physical distance between routers, which is usually measured in
round-trip delay. Round-trip delay ranges anywhere from less than 1ms to as
great as 250ms.
Performance Tuning
Properly configuring the router maximizes its performance. Knowing the round-trip
delay (distance) between routers and the WAN effective data rate (connection
type) allows you to tune the routers for optimal performance. The following tables
provide TCP Window Scaling Factor and Window Size settings for specific
WAN environments.
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/WAN support greater than 1,500byte
frames and are configured for frames greater than 1,500bytes.
NOTE:
For high loss networks, QLogic recommends decreasing the TCP Window
Size from the initial recommended setting until the network achieves optimal
performance.
Table 2-1. T1 / DS-1—1.554 Mbps
Round Trip Delay
(ms)
Total Window Size
(bytes)
Scaling Factor
250 64K 1
100 32K 0
50 32K 0