US Cable Support > Comcast HSI > momentary internet issues-help.

momentary internet issues-help.

Okay. Here goes:

First off, we are a HEAVY internet usage family.

1) Brighton, TN

2) see above

3) intermittent. No specific time of day.

4) Arris TM722G

5) Arris EMTA-->ZyXel USG50-->ZyXel GS1100-24 Gigabit switch. House is completely gigabit wired. Network devices include my primary PC which is an hp Elitebook 8560p running WinXP docked to a gigabit wired connection, a couple old self built AthlonXP systems with Linksys Gigabit NICs, 4 bluray players, Xbox and a Wii. I also have an old Linksys WRT54GL used as an access point only for phones and tablets. Outage affects all devices wired and wireless.

6) AVG antivirus installed. No software firewalls.

Other info:

I'm a blast subscriber. Comcast also carries my home phone service, which is rarely used. Speed test results are always good. 35Mbps down/ 6Mbps up. I used Firefox exclusively.

Modem always seems to look good. All indicators green but I have constant activity on the link L.E.D. (have since the day comcast was installed).

Modem downstream signal levels are all about -.5dbmv in power, and 37 dB SNR. Correcteds column indicates some errors, but nothing to write home about (about 1000 per channel). Uncorrected contains 0 errors for every downstream channel. Upstream power levels are 42.75 and 42.25 dbmv. Logs do not reveal any errors, except once in a while I get "SIP DNS Query Failure" and the next entry is "SIP DNS Query Failure- Cleared".

I have no splitters. Only one "barrel" connection. House was new and this was the first time cable had been installed, so the drop to the house was new, and I ran one new cable to get the connection in my equipment closet. I use Belden cable (I work in radio/tv as an engineer). The cable is in two sections. The new section I laid was a solid copper center RG6. I also reused one section of cable left over from when I had satellite which is a cheaper copper clad steel center RG6.

I have pingplotter, vtrace, and visualroute, but by the time I get them loaded, the problem is usually cleared, so I can't get useful info from them. Although once I believe visual route reported it could not reach the gateway, whos IP is 73.4.1.1.

-Alan

PS Just to reiterate a point in my initial post that *may* be relevant: I wrote a that batch file that I could quickly access to ping my modem, then ping the gateway, and then loop. I caught the outage last night, ran my batch, and the modem responded, the gateway timed out. Once web and email started working again, the gateway also started responding to pings again. The very strange part is we had a netflix movie trailing out, and it was never interrupted.

Everyone has "constant activity on the link L.E.D" even if the connection is not in use.

You could run a (continuous) ping -t to your gateway IP via a minimized command box. If you are there when connectivity drops, bring up the command box and see if packets are being dropped.

I don't know if Comcast would object to a continuous ping, even if they noticed.

I have done something similar:

My router is actually a dual-wan device, but I only have one internet connection. There for a while I did turn on "connectivity check" and extended logging in the router. I set the connectivity check to ping the gateway every 10 or 15 seconds IIRC.

I would have several entries per day where the connectivity check failed, and the router declared WAN1 connection dead. 10 seconds later in the log were entries where the WAN connection was declared active again. After the problem seemed to clear for a while I turned it back off.

-Alan

reply to FirebirdTN
Your modem/line stats seem to be good, and as intermittent as your problem is, it is going to be very difficult to find the source of the problem (as I am sure you know).

Do you own the Arris TM722G, or do you rent it from Comcast? If it is a rental modem, the place to start troubleshooting is to swap the modem. Even if you do own the modem, it might be worthwhile to temporarily rent one from Comcast to see if that fixes the problem; because it is unlikely that Comcast is even going to start looking at the problem until the modem is replaced.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.

I own it. I am a relatively new subscriber. Was an 8 year DSL customer until I found out Comcast was available in my area. I am extremely pleased with the speed, just wish I could nail this issue down.

I'll check into the possibility of a swap. It was purchased at Best Buy (authorized Comcast retail).

-Alan

Just for s&g's I pulled my USG50, and reconfigured my linksys for router duties, just to eliminate my equipment as a source of the issues. Shortly after putting the WRT54GL in, my wife was complaining about internet on her ipad. I was luckily logging at the time. My log entries coincide with her outage:

-snip-
Reply from 73.4.1.1: bytes=32 time=49ms TTL=254
Reply from 73.4.1.1: bytes=32 time=18ms TTL=254
Reply from 73.4.1.1: bytes=32 time=18ms TTL=254
Reply from 73.4.1.1: bytes=32 time=29ms TTL=254
Reply from 73.4.1.1: bytes=32 time=28ms TTL=254
Reply from 73.4.1.1: bytes=32 time=41ms TTL=254
Reply from 73.4.1.1: bytes=32 time=55ms TTL=254
Reply from 73.4.1.1: bytes=32 time=52ms TTL=254
Reply from 73.4.1.1: bytes=32 time=80ms TTL=254
Reply from 73.4.1.1: bytes=32 time=80ms TTL=254
Reply from 73.4.1.1: bytes=32 time=30ms TTL=254
Reply from 73.4.1.1: bytes=32 time=38ms TTL=254
Reply from 73.4.1.1: bytes=32 time=12ms TTL=254
Reply from 73.4.1.1: bytes=32 time=76ms TTL=254
Reply from 73.4.1.1: bytes=32 time=19ms TTL=254
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 73.4.1.1: bytes=32 time=8ms TTL=254
Reply from 73.4.1.1: bytes=32 time=9ms TTL=254
Reply from 73.4.1.1: bytes=32 time=12ms TTL=254
Reply from 73.4.1.1: bytes=32 time=10ms TTL=254
Reply from 73.4.1.1: bytes=32 time=9ms TTL=254
Reply from 73.4.1.1: bytes=32 time=10ms TTL=254
Reply from 73.4.1.1: bytes=32 time=10ms TTL=254
Reply from 73.4.1.1: bytes=32 time=9ms TTL=254
Reply from 73.4.1.1: bytes=32 time=8ms TTL=254
Reply from 73.4.1.1: bytes=32 time=9ms TTL=254
Reply from 73.4.1.1: bytes=32 time=8ms TTL=254
-snip-

-Alan

Well, tech came out yesterday and didn't find a thing. I knew he wouldn't. He also ran packet loss tests, and everything was looking good.

I showed him several days worth of logs (pings only) where I had the outage. For about a week prior to the visit I would start the logging after getting home from work and let it run overnight. I had outages, Monday, Thursday, Friday, and I did some logging on Sat before the tech got there, and had an outage there as well. Tuesday and Wednesday were flawless...no outages at all. He suggested doing tracert logs instead, and when the issue happens to take a close look at modem stats.

The tech I spoke too on the phone when setting up yesterdays appointment wanted a tech out first before swapping the modem out. Also, the tech on the phone is not seeing the drops on their end. Its almost like the modem stays synced, but for some odd reason, a device somewhere in the chain just decids to quit passing data for brief periods of time.

-Alan

What if you hook one machine (Not the one you are testing from) up directly to the router, what happens?

Doesn't matter, you could have two bad routers. How do I know? Because I've done it to myself. Try a single computer, that's NOT the one you are seeing issues from. For all you know at this point it could be a bad NIC in that box.

Your ping batch file doesn't tell you a whole lot. There are about 1000 reasons a ping ICMP packet may not make it through or be responded to, 995 of which would result in your service operating just fine. What you need to do, is look at your modem stats when you see an issue and note any signal changes or corresponding modem log entries.

While I really do appreciate the attempt to help and advice, the chances are pretty slim for 2 bad routers and one bad nic all simultaneously. Besides, when the outage occurs, it happens simultaneously to all computers/devices. Bluray players unable to connect to services, ipads not able to reach wepages/links, my laptop (docked on a wired gigabit connection) sitting at "connecting" to either a web site or my email server, etc. Also, 1 of the routers worked perfectly with my old DSL connection, NEVER requiring a reboot, although I probably did end up rebooting it every six months or so for one odd reason or another. The other router was purchased after the switch to cable.

I'm still going to go thru the motions, and do as you and the tech suggest.

I understand that my ping batch files doesn't tell me alot....but at the same time they do. I run batch files on one computer, and have issue on all. I look at my logs, and low and behold, ping timesouts match precisely with the outage. I doubt its coincidental. Also, what I didn't post is I simultaneously log replies from the cable modem (on the wan side of my router of course); modem NEVER times out, even when outages occur, but obviously, my first hop does time out at precisely the same time we experience the connectivity drop.

As me and the tech were chatting, we both agree packet loss is normal. It happens. I get that. On a 12 hour log I still might see a stray "request timed out" here and there, but 10 in a row that coincides with my outage again just can't be coincidence. It reminds me of something he said to me....I think it was 3% packet loss is acceptable. Okay, sounds perfectly okay to me, but during a 24 period, if that 3% loss is all right together, thats a problem.

I realize the nature of this problem is such that its going to take some time and patience to figure out what is causing it. The main reason I posted here was to prevent "reinvention" of the wheel if someone has been down this road before.

-Alan

You have no idea if the router(s) are bad or not - you are running the test from the same computer, that could have a bad nic, which would make everything look bad down the line That was why I suggested a different machine, directly connected to the modem.

I am not saying that it's for sure your equipment, but from what you have posted, nothing you have shown indicates a problem outside of your network yet. You NEED to post the modem stats and log while you are seeing your "outage". That will tell us what is going on.

Modem stats are above. Signal levels look darn near perfect. Also, by the time I realize I have an issue, its almost too late to get to the modem to look at the stats.

As far as modem log, it doesn't reveal any issues. Also Comcast is not seeing the drop. I do not believe it is losing sync, just again something in the chain just stops passing data for brief periods of time.

I did not have any issues at all Mon-Wed, and my "ping" logs (and now tracert logs as well per tech request) show zero issue and zero lost packets.

Thursday I had an outage, and again my logs reflect it, as the ping log looks exactly like above. Also, tracert shows same thing....perfect trace response until the outage.

This is all again thru router. Next step...pc directly to modem and repeat.

-Alan

reply to FirebirdTN
Grab a copy of PingPlotter Standard and let it run until you have the issue. You can open a second copy and and have it pinging the modem while you are pinging a location on the internet in a different copy.

»www.pingplotter.com/

reply to FirebirdTN
You should already be at the PC direct to the modem stage, and NOT the computer you are using for monitoring now. Ping doesn't help at all, because you have no idea what is causing the loss or where. Ping Plotter will help, but if there is no corresponding modem issues, it's moving towards not being a comcast issue. If it was a headend issue, this would have already set off alarms that would have been addresses as a lot of people would be experiencing it.

But, a Ping Plotter log will help narrow the scope a bit.

Beachintech,

I do apologize, maybe I'm not relaying my test results satisfactorily.

When I say I'm running a "ping" test, I am not just running a single test. I have two separate pings going simultaneously. One that pings my modem. The other that pings my first hop.

To date, I have not seen a single lost ICMP request to my modem, even during outages. Although that doesn't necessarily prove anything, it would seem to indicate communication between my LAN and at least the modem ethernet interface is rock solid.

ICMP test results to my first hop looks almost perfect as well...UNTIL an outage. So even during an "outage" ICMP requests still make it thru my router to the modem and modem responses always make it back, but ICMP requests do not make it to the first hop when the problem arises.

As to the possibility of a questionable NIC, again if the NIC was intermittent, then I should be seeing time outs to ICMP packets to both my modem and my first internet hop. Again, modem results show not a single lost packet.

Also, as to using a different PC than one I am experiencing the issues on...I am NOT solely using my main PC when the outage is experienced, nor am I looking at the logs solely as an indicator of an outage. Quite on the contrary. What I in fact do is get home from work, start the logging, then go do something else. As soon as someone in the house yells "Dad the internet isn't working again" (whether they are on an ipad, Xbox, bluray player, their own PC, etc) I then quickly run back to my logging computer and pull up the logs to see if the "timeouts" coincide with the outage. In EVERY single case, they do. Also, I am not just going by family member's words for these outages. I have experienced them first hand myself as well.

The reason I had not removed the router yet, is I want to arm myself with logs (again Tracert logs are per comcast tech request) both with and without the router.

-Alan

Well, picked up what looks like an old beat up RCA. Looks like a DOCSIS 2 modem. Lost 10 Megs on the download speed, and upload speed is cut in half. I don't care, so long as its stable.

The things has seen better days though. Beat up pretty good.

I didn't realize by the time I got it home and really looked at it, it didn't even have a backup battery in it. Good thing my equipment closet is on a UPS.

Fingers crossed.

-Alan