mlcarson
join:2001-09-20
Las Cruces, NM
| [Connectivity] Intermittent packet loss
I've about had it with Comcast. Since about mid August, I started having Internet connectivity issues. Repeated calls to Comcast yielded lots of tech visits but the problem remains. I've had all my splitters replaced (only 1 before the cable modem). I've had all of my indoor cable replaced. I've had my underground cable replaced. I had my modem (SB5101) replaced. I had some kind of outdoor line tap replaced. The last line tech who came out in November managed to prevent problems in December but they recurred in January.
The problem is intermittent packet loss. For example, this morning from 7:00am to 1pm I had 90% packet loss on ICMP packets of byte size 512. It was about 10-20% on the standard 32 byte ICMP packet size. Power cycling the modem yielded a very long boot time (up to an hour) due to the inability to obtain a DHCP address and still had the same packet loss after it eventually did get one. Comcast executive account assistants (phone support) were able to see the packet loss but couldn't obtain any signal stats presumably due to the bad connection. Everything seems fine this afternoon and I'm getting zero percent packet loss regardless of packet size. A tech is scheduled to come out on Saturday (3 days is the earliest appointment) but the problem usually lasts less than 8 hrs.
10 days ago I had the exact same problem. The tech was scheduled to come out yesterday (earliest appointment was 9 days from problem date) and I canceled the appointment when he called since there was no packet or signal loss yesterday. And the tech was threatening me with service charges if he got out here and didn't find anything. I've had so many techs come out and anybody less than a line tech basically just comes out and takes a signal measurement and reterminates a connection and says everything looks good. The problem either doesn't happen when they're here or if it does -- they don't have the necessary equipment to do any diagnostics.
I've got VOIP service so every time there is a problem -- I have to use a prepaid cell phone to contact Comcast. This costs me $2-$3 a pop due to hold time and the like. I agreed to rent one of their cable modems for a few months to rule out my own modem (finally turned it in after last week's outage since it didn't make any difference).
I love the service when it works but I've had so many issues that it hardly seems worth the speed increase over DSL when I can't depend on it. My latest bill also shows rate increases coming. Effective in March, basic cable is going up from $11 to $14.99. HSI is $42.95 here so that will drive it up to $57.94. Dry loop DSL would be $28 (3MBs) - $38 (6MBs if avail).
Cable modem signal stats here are:
Downstream
----------
SNR: 38.3dB
Power Level: 5.5 dBmV
Upstream
--------
Power Level: 35.8 dBmV
=========
I had phone support do some testing of neighbor's accounts when I was having packet loss last week. I'm apparently the last guy on the street with cable modem service. 2 doors up from me there was no packet loss while my modem showed it. The only house in between the good service and mine shares the same green cable box as my connection. They seem to place one every other house here. If there's a physical problem -- it would seem like it would be in the cable between the 2 houses. Why is this so hard to fix?
Why do I have to have service tech's come to my house days later when the problem no longer exists when this has all been looked at before? I wish they could just send the line tech's out promptly while the problem exists so it wouldn't have lasted 5-6 months and counting.
Ironically, the primary reason I switched to Comcast was originally reliability since I started having sync issues with DSL. |
|
gar187er
Premium Alcoholic
join:2006-06-24
Dover, DE | what do your numbers look like when you have packet loss? |
|
helter
join:2007-09-11
Silverdale, WA
| reply to mlcarson
»Connection dies
PS packet loss can occur on DSL too and its actually can be harder to trace down the fault on twisted pair than coax. 
That said try to follow the thread above. |
|
mlcarson
join:2001-09-20
Las Cruces, NM
| reply to gar187er
My cable modem status look the same whether I'm having packet loss or not. Tech's always say the numbers look fine. Problem is getting more prominent again. I've had issues Wed, Thurs, Friday. Wed and Thurs it was primarily in the morning. Friday was all day. Checked with the neighbor who supposedly didn't have packet loss one of the days that I did. She said that she's been having connection issues almost daily but doesn't bother reporting them anymore. Just expects things to get better in a few hours and claims it's better than it was a few months back when the problems would last up to a week at a time.
Comcast seems to use their online tools to check signal strengths and connectivity with standard 32 byte ICMP packets. If these don't show a problem -- then everything is deemed fine. My signal strengths seem to have been fine and a standard ping doesn't always show the problem. I can have 5-10% packet loss with a standard ping size but 90-100% packet loss with a 512 byte packet size.
Tech is scheduled to visit tomorrow afternoon. Expect everything will be working fine when he arrives or he'll simply be a no show.
Nothing too interesting in the "Connection dies" thread. I'm currently using a SB5101 but had swapped for a webstar one which didn't seem to make any difference. I think there are just issues with either the physical cabling on my street or the node itself and the subscribers are so worn down with the constant outages that nobody bothers to report them anymore. So, Comcast continues to tell me that it's just me and won't dedicate the resources to fix it. |
|
gar187er
Premium Alcoholic
join:2006-06-24
Dover, DE
| reply to mlcarson
quote:
I'm currently using a SB5101 but had swapped for a webstar one which didn't seem to make any difference. I think there are just issues with either the physical cabling on my street or the node itself and the subscribers are so worn down with the constant outages that nobody bothers to report them anymore. So, Comcast continues to tell me that it's just me and won't dedicate the resources to fix it.
those issues would surface in signal abnormalities.....
where do you ping and get that loss? at the destination? somewhere along the way?! level 3 router? aat? |
|
mlcarson
join:2001-09-20
Las Cruces, NM
| Believe it occurred first hop after the cable modem. I was pinging the comcast website and a DNS server. Both sites can go days without dropping a packet if no problem exists. Pings to my own router show no packet loss. Pings to the cable modem show no packet loss. Pings anywhere else show high loss and drop packets at the same time. This rules out switches, router, and all ethernet cabling. Taking the router out temporarily made no difference either.
I'm at work so can't do a traceroute to see which public IP address was the first hop. |
|
helter
join:2007-09-11
Silverdale, WA
1 edit | reply to mlcarson
Nothing too interesting in that thread?
Oh well sorry to hear that. So ping plotter showing you which hop is loosing the packets is not interesting to you. Hmm... |
|
mlcarson
join:2001-09-20
Las Cruces, NM
| Ping plotter is not interesting at all if your packets are dropping at the first hop and Comcast is seeing the same packet loss you are to the modem.
In my case, the IP address is 68.86.140.225.
Had to cancel my tech appointment again. He said he had a half dozen or so that cancelled in the neighborhood since today there's no loss. Wed-Fri -- lots of loss; tech arrives on Sat and there's no problem. I guess I can only hope they actually fixed something Friday but the history of it's been that nothing gets fixed -- the problem just recurs in a couple weeks. |
|
