Slow download speeds...is it the ISP or the CPU?
Posted: Sat Feb 07, 2009 11:08 pm
Hi,
Thanks in advance for any guidance anyone here can provide.
I'm paying for a five Mbps down/1Mbps up cable service via Charter (Suffolk, VA). This is a new computer running Vista. I have an old cable modem (Motorola SB4200) connected via ethernet to my linksys wireless router. I have another computer elsewhere in the house connected wirelessly. Interestingly...the other computer seems to have reasonable download and upload speeds (around 3 Mbps earlier this evening at the same time primary computer was less than 1 Mbps).
I noticed about a week ago that the speed started to get horrible in the evenings (less than 1 Mbps down as measured via speakeasy.net).
I spoke with Charter service. No known issues in my area. He had me do a netstat check at the command prompt. It showed what he said was an excessive amount of TCP/UDP hits that were indicative of spyware.
Norton showed nothing but Spybot caught a virtumonde.sci trojan. I reran in safe mode and dumped the trojan. Still wicked slow...30 minutes to download Ad Aware.
IP Address: XX.XX.X.X (XX.XX.X.X)
Client OS: Windows Vista
Browser: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; WOW64; GTB5; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.0.04506; Media Center PC 5.0)
Please Read the Analyzer FAQ if the above is not your IP address.
TCP options string = 020405b40103030201010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.
Default TCP Receive Window (RWIN) = 65700
RWIN Scaling (RFC1323) = 2 bits (scale factor: 2^2=4)
Unscaled TCP Receive Window = 16425
In Windows Vista, unless "TCP/IP Auto-Tuning" is disabled, only the Current TCP Window is displayed. Use the SG Vista TCP/IP patch instead of the TCP Optimizer for automatic tweaking.
RWIN is not fully optimized (even though it is a comparatively large number). The unscaled RWIN value is lower than it should be. Also, RWIN being close to and above 65535 does not justify the header overhead of enabling TCP 1323 Options. You might want to use one of the recommended RWIN values below.
RWIN is a multiple of MSS
Other RWIN values that might work well with your current MTU/MSS:
64240 (up to 2 Mbit lines, depending on latency. MSS * 44)
128480 (1-5 Mbit lines, depending on latency. MSS * 44 * 2)
256960 (2-14 Mbit lines, depending on latency. MSS * 44 * 2^2)
513920 (8-30 Mbit lines, depending on latency. MSS * 44 * 2^3)
1027840 (25-60 Mbit lines depending on latency. MSS * 44 * 2^4)
bandwidth * delay product (Note this is not a speed test):
Your TCP Window limits you to: 2628 kbps (329 KBytes/s) @ 200ms
Your TCP Window limits you to: 1051 kbps (131 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 111 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000 (0)
Thanks in advance for any guidance anyone here can provide.
I'm paying for a five Mbps down/1Mbps up cable service via Charter (Suffolk, VA). This is a new computer running Vista. I have an old cable modem (Motorola SB4200) connected via ethernet to my linksys wireless router. I have another computer elsewhere in the house connected wirelessly. Interestingly...the other computer seems to have reasonable download and upload speeds (around 3 Mbps earlier this evening at the same time primary computer was less than 1 Mbps).
I noticed about a week ago that the speed started to get horrible in the evenings (less than 1 Mbps down as measured via speakeasy.net).
I spoke with Charter service. No known issues in my area. He had me do a netstat check at the command prompt. It showed what he said was an excessive amount of TCP/UDP hits that were indicative of spyware.
Norton showed nothing but Spybot caught a virtumonde.sci trojan. I reran in safe mode and dumped the trojan. Still wicked slow...30 minutes to download Ad Aware.
IP Address: XX.XX.X.X (XX.XX.X.X)
Client OS: Windows Vista
Browser: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; WOW64; GTB5; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.0.04506; Media Center PC 5.0)
Please Read the Analyzer FAQ if the above is not your IP address.
TCP options string = 020405b40103030201010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.
Default TCP Receive Window (RWIN) = 65700
RWIN Scaling (RFC1323) = 2 bits (scale factor: 2^2=4)
Unscaled TCP Receive Window = 16425
In Windows Vista, unless "TCP/IP Auto-Tuning" is disabled, only the Current TCP Window is displayed. Use the SG Vista TCP/IP patch instead of the TCP Optimizer for automatic tweaking.
RWIN is not fully optimized (even though it is a comparatively large number). The unscaled RWIN value is lower than it should be. Also, RWIN being close to and above 65535 does not justify the header overhead of enabling TCP 1323 Options. You might want to use one of the recommended RWIN values below.
RWIN is a multiple of MSS
Other RWIN values that might work well with your current MTU/MSS:
64240 (up to 2 Mbit lines, depending on latency. MSS * 44)
128480 (1-5 Mbit lines, depending on latency. MSS * 44 * 2)
256960 (2-14 Mbit lines, depending on latency. MSS * 44 * 2^2)
513920 (8-30 Mbit lines, depending on latency. MSS * 44 * 2^3)
1027840 (25-60 Mbit lines depending on latency. MSS * 44 * 2^4)
bandwidth * delay product (Note this is not a speed test):
Your TCP Window limits you to: 2628 kbps (329 KBytes/s) @ 200ms
Your TCP Window limits you to: 1051 kbps (131 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 111 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000 (0)