Then, convert the MWS to a recommended scale factor by dividing it by the default window size
(32,768 bytes). Use
Table 21 (page 124)
to determine the scale factor.
Table 21 TCP window size scale factors
Scale factor / TCP Window size
MWS scale result
0 / 32KB
0 to 2
1 / 64KB
2 to 4
2 / 128KB
4 to 8
3 / 256KB
8 to 16
4 / 512KB
16 to 32
5 / 1MB
32 to 64
6 / 2MB
64 to 128
7 / 4MB
128 to 256
8 / 8MB
256 to 512
9 / 16MB
512 or greater
TCP window size and scaling factor recommendations
Table 22 (page 124)
through
Table 28 (page 126)
provide TCP window size and scaling factor
settings for specific WAN environments. These tables are organized by typical link speed.
NOTE:
The TCP window size recommendations listed in
Table 22 (page 124)
through
Table 28 (page 126)
are based on low-loss networks (0.0012% average packet-loss ratio over 24
hours). For higher-loss, longer-latency networks, you should reduce the recommended window size
and scaling factor by one setting to compensate for the increased number of packet retransmissions.
Table 22 T1/DS-1 1.554 Mb/sec (bandwidth = 1 Mb)
Scaling factor (2
n
)
Window size (bytes)
Round trip time (RTT) in ms
1
64K
250
0
32K
100
0
32K
50
0
32K
25
0
32K
20
0
32K
15
0
32K
10
0
32K
5
0
32K
2.5
0
32K
1 or less
Table 23 T3/DS-3 45 Mb/sec (bandwidth = 43 Mb)
Scaling factor (2
n
)
Window size (bytes)
Round trip time (RTT) in ms
5
1M
250
4
512K
100
3
256K
50
124
MPX200 FCIP