Again, combined security and speed (here because it adds to the above section B): Added to that one above in B? Using ping -l 1400 -f (start at 1300 and go up to 1500 on Cable/DSL) and seeing your LOWEST ms times on those pings? You can figure out your MTU to add as well under each Network Adapter Interface!

EXAMPLE: ping -l 1500 -f www.twcny.rr.com

(Ping your DNS connection Default Gateway from your ISP if you can, that's your doorway! That is determined by using IPConfig /all from the commandline, or using wntipcfg.exe from the reskit... a GUI one like the winipcfg.exe in Win9x (both from MS, both free now). If not, next best bet is to ping your ISP's webpage!)

1500 is the default and 1472 seems to be the largest anyone can do without fragmentation... the ping command will show you your best one and when it starts to fragment? You use the one before it that did not as YOUR individually best value!

They look like this in the registry:" HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesTcpipParametersAdapters{09EC4F91-EABC-419C-BEF4-433971144FE5}"

Under each of them, add in the MTU as a DWORD value with your best non-fragmented packet size after doing the ping test I showed above. In the above tip I wrote on the Parameters section? Make that equal to your EXACT TcpRecvSegmentSize and TcpSendSegmentSize so you take in the BIGGEST chunks per packet you can at once and do not fragment!)

Then, get your RWIN:

On cablemodems, the generic network MTU/MaxMTU is usually 1472 (largest non fragmented value) a.k.a 1500. -40 would be 1460 MSS.

56K modems use 576 MTU and 536MSS.

The generic PPOE (dsl) mtu is 1492. -48 (40bytes for the default TCP OPTIONS + 8 bytes for the ppoe header involved) 1444 MSS.

The -40 amount is TCP HEADER size. Which can be affected by certain RFC options like Timestampings.

The RWIN amount needs to be an even multiple of MSS x even number the forumla I use is:

Download Rate in Kb (kilobits) x 1024 = n
n * .5 (.5 is the latency of the line or 500ms) = n
n / 8 = n

1472 is my MTU/MaxMTU derived from ping -l 1472 -f to my ISP gateway and website also... largest I could be before fragmenting packets!
472 - 48 = 1424 + 12 packets gained by using Tcp1230pts TimeStamps removed on packet headers = 1436
512 x 1024 = 524288
524288 x .5 = 262144
262144 / 8 = 32768
32768 / 1436 = 22.8 ~ 23
23 x 1436 = 33028 my RWIN figure...

Now you've got a number you can utilize for the next step!

Take that last N / MSS = n You'll usually get something like 30.23341341 Round up/down to the nearest even number. So in our case it would be 30 Then Take 30 x MSS = RWIN VALUE

This RWIN value is added right alongside MTU in your registry interface keys!

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