Not getting anywhere near the speeds I should be...

[hadriel]

For a very long time, most likely since we've had the service, I have gotten very poor speeds. Where we should be getting 512Kbps-1Mbps according to our HSI plan, the maximum speed I have ever gotten is and was 91Kbps. According to my router page(192.168.1.1) it should be862 Kbps down / 159 Kbps up. I have benchmarked it many times, and the average is 91kbps down 16kbps up. The DSL lines and my phone lines have been tested and are fine. 

Heres from Speedtest.net a few minutes ago:

And the Verizon Broadband Speed test:

Analysis information:

Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
SendBufferSize set to [8192]
running 10s outbound test (client to server) . . . . . 131.44Kb/s
running 10s inbound test (server to client) . . . . . . 735.73kb/s

------ Client System Details ------
OS data: Name = Windows 7, Architecture = x86, Version = 6.1
Java data: Vendor = Oracle Corporation, Version = 1.7.0

------ Web100 Detailed Analysis ------
Client Receive Window detected at 17424 bytes.
Cable modem/DSL/T1 link found.
Link set to Full Duplex mode
No network congestion discovered.
Good network cable(s) found
Normal duplex operation found.

Web100 reports the Round trip time = 178.62 msec; the Packet size = 1452 Bytes; and
No packet loss - but packets arrived out-of-order 0.26% of the time
This connection is receiver limited 33.05% of the time.
Increasing the the client's receive buffer (17.0 KB) will improve performance
This connection is sender limited 64.49% of the time.
This connection is network limited 2.46% of the time.

Web100 reports TCP negotiated the optional Performance Settings to:
RFC 2018 Selective Acknowledgment: ON
RFC 896 Nagle Algorithm: ON
RFC 3168 Explicit Congestion Notification: OFF
RFC 1323 Time Stamping: OFF
RFC 1323 Window Scaling: ON
Information: Network Middlebox is modifying MSS variable
Server IP addresses are preserved End-to-End
Information: Network Address Translation (NAT) box is modifying the Client's IP address
Server says [XX.XX.XXX.XXX] but Client says [192.168.1.24]

External IP is replaced with X's

Not sure why the speeds are so unbearably low, and can Verizon fix this?

[jmw1950]

First of all it isn't clear that you aren't getting the speed Verizon promised. You are confusing two different units of measure.

Kilobytes per second versus Kilobits per second. There are 8 bits in a byte, so 91 kilobytes per second is 728 kilobits per second, the speed test measures 735 kilobits per second.  16 kilobytes per second is 128 kilobits per seconds, and that is all the bottom tier of DSL service is good for.  Verizons lowest tier DSL service is 512k-1 million BITS per second down, and 128k bits per second up.

One of the things the speed test is telling us is that you don't have enough or large enough buffers. Note that the test says you are sender limited as opposed to network limited about 65% of the time. Windows 7 allocates buffer space dynamically, so if you don't use it, windows 7 de-allocates space, and isn't very responsive about rolling it back out. There are other places that can tell you how to get Windows 7 to allocate more buffer space for you. I suggest 64k buffering as a bare minimum.

More importantly, you have not posted your transceiver statistics. The transceiver stats will show if your line is capable of higher speeds than you have today. You would have to upgrade to a higher tier to get higher speeds (cost $'s), but it may be possible to go considerable faster. That would depend upon the quality and length of the copper pair between you and the central office.

So please post your transceiver statistics so we can see the losses and transmit levels.

[smith6612]

Going to need Transceiver Statistics to answer this question right now. It's also worth pointing out that the speed the modem reports and what you get are going to be two different things. By nature, DSL lines will be overprovisioned instead of being set at your "max" line rate to make up for mainly the ATM overhead that occurs on DSL. The value is somewhere around 14% of the total line speed goes towards overhead, 10% of it being from ATM+PPPoE, perhaps a little more, and perhaps another 3-5% of the speed going towards regular TCP/IP packet overhead. Quite inefficient in these days to have that much overhead where the elimination of say, an ATM network may increase speeds a bit.

[hadriel]

Oh wow I can't believe I mixed those two up. Everything seems to make more sense now...

Here's the transceiver statistics:

Transceiver Statistics

Transceiver Revision A2pB020b3.d20h Vendor ID Code 4D54 Line Mode ADSL_2plus Data Path FAST

Transceiver Information Down Stream Path Up Stream Path DSL Speed (Kbits/Sec) 862 159 Margin (dB) 31.2 40.0 Line Attenuation (dB) 26.0 12.0 Transmit Power (dBm) -1.0 11.4

I guess my only other question would be what should I make the buffer size for my PC then?

[jmw1950]

In this age of cheap memory (when I started in the business, 128k of core memory cost $70,000), it makes no sense to skimp on buffers. I'd go with 512kb. I use 1mb, but I have FiOS Service, which is a whole lot faster. Frankly in today;s multi-gigabyte memory envirornments, even a 1mb for the buffers is a drop in the proverbial bucket.

Your transcevier statistics show that you could easly go to the 3mbps/768kbs tier for DSL service,and probably  all the way to the 7mbps tier. The line attenuation  and margin figures suggest you either have an excellent copper pair, or are quite close to the Central office(or both). You would need to talk to Verizon to determine the ultimate capability, because there may be issues with capacity upstream from the Central Office.

So the short answer is you should be able to get to at least 3 times your current DSL speed, and  quite possibly much more.

[smith6612]

You have a nice healthy line there. Right now you can get Verizon to bump your speed to 1Mbps/384kbps so that you fall into the max speed of your tier. You could also consider going up a package, which will give you hopefully a full 10Mbps/1Mbps provided Verizon isn't capping your DSLAM to 3Mbps. You might slip by with 15Mbps if the line is running that clean.