SG Broadband Community

Hi. I need some cablenut settings for my Comcast 1800/128 connection (yep, its 1800 -- not 1500 contrary to popular belief). I'm using Windows 2000 with 512MB of SDRAM and a 1.4GHz P4 processor.

SG Analyzer results are as follows:

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TCP options string = 020405b401010402

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:
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 = 47 hops
TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349)= 00000000

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Thx for your help.

OK, your TcpWindowSize looks perfect but make sure you have the rest of these values in CableNut:

DefaultReceiveWindow = 230400
DefaultSendWindow = 16384
DisableAddressSharing = 1
InitialLargeBufferCount = 100
InitialMediumBufferCount = 240
InitialSmallBufferCount = 320
LargeBufferSize = 81920
MaxFastTransmit = 64000
MediumBufferSize = 15040
PriorityBoost = 0
SmallBufferSize = 1280
TransmitWorker = 32
FastSendDatagramThreshold = 4096
EnableFastRouteLookup = 1
EnablePMTUDiscovery = 1
IgnorePushBitsOnReceive = 0
GlobalMaxTcpWindowSize = 64240
MaxFreeTcbs = 8000
MaxHashTableSize = 16384
MaxNormLookupMemory = 5000000
SackOpts = 1
SynAttackProtect = 1
Tcp1323Opts = 0
TcpLogLevel = 1
TcpMaxDupAcks = 2
TcpMaxHalfOpen = 100
TcpMaxHalfRetried = 80
TcpRecvSegmentSize = 1460
TcpSendSegmentSize = 1460
TcpTimedWaitDelay = 30
TcpUseRFC1122UrgentPointer = 0
TcpWindowSize = 64240
MaxConnectionsPer1_0Server = 20
MaxConnectionsPerServer = 10
DefaultTTL = 64
DisableUserTOSSetting = 0
TcpMaxDataRetransmissions = 6
DefaultTOSValue = 92

LOL.... that took less than a minute. Thx for the quick response.

I have a problem... my RWIN won't go above 64240. This has happened before, and I installed SG Optimizer and it resolved itself, but is there a patch to fix this?

Your confusing the AFD values and the TCP/IP values. DefaultReceiveWindow is an AFD value and uses RAM as a buffer for data, the TCP/IP Analyzer shows your TCP/IP values not your AFD values...... GloabalMaxTcpWindowSize & TcpWindowSize = RWIN (in the TCP/IP Analyzer).

Oh, didn't notice they are different in those settings.

Thx.