Bad pings & packet loss at node

[apmonte]

I've been working with my cable company (Insight Communications) over the past few months to resolve an problem I am having with pings & packet loss while gaming.

Problem:

Seemingly, anything over 3-4kBps will cause my ping times to go up. I am using a registered copy of PingPlotter to monitor my ping times. Once I cross that threshold (it varies from day to day, hour to hour), my in-game ping times sore to 500ms. Running a test by uploading a large Word file to my web space showed ping times to 600ms. Even repetative refreshing of web pages show increases in the 200-300ms range. Ping times fluctuate a bit under no load, but generally look good. (Notice the current value column that indicates the pings I was getting after I exited the game)

This is an image of PingPlotter while gaming.

http://members.home.com/apmonte/badping.jpg


The Solution:

I don't have one. The techs have been out numerous times, I've got a new drop, new cables, new modem, tap, etc... They've "shot the line" and performed whatever other meaningless tests they know how, but I am still having problems. They expect to have some new analyzer in this month that they plan to use to somehow check the node, but I don't hold out much hope.

My cable setup looks like this, more or less. The COM21 modem is gone now, replaced by a 3com SharkFin. The tap has also been replaced. Removing the cable router made no difference.

http://members.home.com/apmonte/StructuredWiring.html

This website will be gone on the 28th when I am transitioned from @home to ATT.

I really need some suggestions on where to point these guys to. I need some specifics as not to make their job to difficult. If you say that it's a problem with the headend, tell me how they can diagnose the problem and what the solution might be.

I'd jump ship for DSL, but it's not available in my area yet.

All suggestions are welcome!

Thanks!

Aaron

[MosDef112]

Very neat wiring job! I wish I had thought of that before wiring my apartment. :)

I pinged what seems to be either your headend or a router in your area, bb1-fe0-0.rockfd1.il.home.net [24.255.247.1], and latency averages 45ms which is not bad considering that I live in New York. You may want to check your signal levels and/or eliminate that splitter into which you connect your cable modem and try it out that way for a day or two. Not really familiar with the 3Com modem, but you may want to check the firmware as well. I have read about stability issues with the Sharkfin modem on older firmware versions.

Man.. I really can't appreciate that neat wiring job enough! Next time I move into a different apartment I may spend the money you did for something like that.

[Kip Patterson]

This isn't going to be the answer you wanted.

Your ping times are excellent.

You cannot measure latency when any other application is running. The packets sent by the traceroute program have to wait their turn in the queue in your PC, and the returned packets get the same treatment in the queue at the CMTS.

Let's take the data you posted, and I'll assume that your RWIN is 64kbytes, and that Insight's cap on your download is 2mbits.

60ms ping x 2mbits per second is 120kbits of data in transit over the net, or 15kbytes. That means that there is 49kbytes already at the queue in the CMTS.

49kbytes x 8 / 2mbits = 200 ms. additional "latency" that really isn't there.

Kip

[MosDef112]

So the answer would be to lower the RWIN?

[apmonte]

Originally posted by Kip Patterson
This isn't going to be the answer you wanted.

Your ping times are excellent.

You cannot measure latency when any other application is running. The packets sent by the traceroute program have to wait their turn in the queue in your PC, and the returned packets get the same treatment in the queue at the CMTS.

Let's take the data you posted, and I'll assume that your RWIN is 64kbytes, and that Insight's cap on your download is 2mbits.

60ms ping x 2mbits per second is 120kbits of data in transit over the net, or 15kbytes. That means that there is 49kbytes already at the queue in the CMTS.

49kbytes x 8 / 2mbits = 200 ms. additional "latency" that really isn't there.

Kip

Kip -

Thanks for the response. Please explain to me how my ping times to my router are rock solid with a max of 10ms, while my pings to the node and beyond look horrible.

You lost me with the 49kbytes. Does your example apply even if I am not downloading at max rate? Typically while gaming, I have Unreal Tournament set for a netspeed of 4000 - or 4000 bytes/sec up/down. 4000 bytes/sec x 8 bits/byte = 32kbps, far below my 128kbps upload cap. I think download cap is about 2M. I will not typically have any other net resource running while gaming.

And do you have any suggestions as to how I could more accurately track down the problems that are causing my high ping times and packet loss while gaming? (I really thought running PP in the background was the answer) I could care less about ping times when I'm surfing, so long as things load or download in a timely fashion.

Thanks!

Aaron

[apmonte]

Originally posted by MosDef112
Very neat wiring job! I wish I had thought of that before wiring my apartment. :)

I pinged what seems to be either your headend or a router in your area, bb1-fe0-0.rockfd1.il.home.net [24.255.247.1], and latency averages 45ms which is not bad considering that I live in New York. You may want to check your signal levels and/or eliminate that splitter into which you connect your cable modem and try it out that way for a day or two. Not really familiar with the 3Com modem, but you may want to check the firmware as well. I have read about stability issues with the Sharkfin modem on older firmware versions.

Man.. I really can't appreciate that neat wiring job enough! Next time I move into a different apartment I may spend the money you did for something like that.

Thanks for the kind words! :)

The wiring project was fun and interesting, but I wouldn't want to do it for a living!

I've already bypassed everything that I can think of. I've bypassed the tap and the router, changed NICs, moved from W2k Pro to XP Pro, etc.. Nothing I change on my end seems to help. I had the same problems with the COM21 modem that the 3com replaced. Line levels all look good according to the techs that have been out here several times.

[MosDef112]

Why not do it for a living? It is fun, and you get to build something useful every day. :)

Eh.. It sucks when you have a problem in front of you which you understand more than the ISP does. At least they're being proactive about it though.

Were you having this problem just recently?

[Kip Patterson]

Two questions -

What is your RWIN?

I'm not sure what you mean by "node". Nodes are analog devices and don't have IP's.

Kip

[Cable_Dood]

Yeah....I'm with Kip here: your router pings out ok. A node is a tranceiver-like device on your cable line that converts RF to light and vice-versa....it's where you hit fiber optics.

I was seeing similar problems in my market before we left @Home. I pounded my head on the table for weeks and was never able to resolve it. Same equipment and now no problem since we're off the @Home network.

I suspected lot of stuff....poor routing, lack of network maintenance, @home pimping off their pipe for extra revenue.....but I couldn't prove any of it.

I would say sit tight until you get cut over and look for vast improvements in network consistency, if not throughput.

p.s. I'm sure I'll get flamed again for bashing @Home.....but let's get real. They were awesome once, but they aren't the same company they used to be. How dedicated would you be if you knew that you were going to be out of a job in a couple of weeks? I'm impressed that the guys and gals there have the diligence to keep showing up.

[apmonte]

Originally posted by Kip Patterson
Two questions -

What is your RWIN?

I'm not sure what you mean by "node". Nodes are analog devices and don't have IP's.

Kip

This is the data I gather about my settings from DSL reports:

Receive Window (RWIN): 32120
Window Scaling: 0
Path MTU Discovery: ON
RFC1323 Window Scaling: ON
RFC1323 Time Stamping: OFF
Selective Acks: ON
MSS requested: 1460
TTL: 64
(less any hops behind firewall)
TTL remaining: 51


And I guess by "node" I mean my first hop. I assumed that to be whatever is at the pole, but that may not be correct. Whatever piece of hardward is at the 10.96 IP.

We're supposed to make a full conversion to ATT on the 28th, so maybe that will help, but I have my doubts as I've been battling this demon for months.