SG Broadband Community

Hello.

I'm trying to figure out my RWIN but am finding alot of inconsistencies. I've run a tracert on about 7 sites and my maximum ms #'s are all over the place.

On most sites the average max ms is 70. On one of these 7 sites, the max was 110 ms and on my 7th tracert of a site the max was 632.

I'd like to figure out my RWIN using the formula but I don't know what to put in as the maximum anticipated latency.

Any help would be greatly appreciated. Thanks.

Windows XP SP2
Optimum Online ISP (Cable)
I believe the advertised speeds are 10000/100

MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.

Default Receive Window (RWIN) = 64240
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 64240

RWIN is a multiple of MSS
Other values for RWIN that might work well with your current MTU/MSS:
513920 (MSS x 44 * scale factor of 8)
256960 (MSS x 44 * scale factor of 4)
128480 (MSS x 44 * scale factor of 2)
bandwidth * delay product (Note this is not a speed test):

Your RcvWindow limits you to: 2569.6 kbps (321.2 KBytes/s) @ 200ms
Your RcvWindow limits you to: 1027.84 kbps (128.48 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 119 hops

TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000

I would suggest using a Latency value of 100. The calculation would then be:

(10000 * 100 / 8) / 1460 = 85.6164

Round to the nearest whole number which would be 86

86 * 1460 = 125560


I would just use 128480 for your RWIN. Remember to set Tcp13210pts to 1 to turn on Windows Scaling.