Improving Connection Reliability

[istari675]

I am having a lot of packet loss and general outages on my internet. I currently have comcast and any hopes of having them fix this issue have been shot down. They have visited my house 3 times in the past few months only for each of them to try something new and have the issue come back the next night. The device is running on a hard line.

Everything in my network has been replaced in the time this issue has been going on. When I purchased my own modem I chose whatever was compatable so I didnt think about buying a high quality, or high performance one. It seemed to help for a few months but it seems the issue has come back in full force. I am considering upgrading from a SB6121 modem to a SB6141. Do you think this upgrade will help at all? If not what would you suggest.

Router is NETGEAR WNR2000-100NAR if you are interested. But I have used 5 different routers on my home network during the lifespan of this issue.

 

[Terry Kennedy]

I am having a lot of packet loss and general outages on my internet. I currently have comcast and any hopes of having them fix this issue have been shot down. They have visited my house 3 times in the past few months only for each of them to try something new and have the issue come back the next night. The device is running on a hard line.

I have Comcast Business Internet at one site and have been surprised at how well it has been working and how pro-active they are - they occasionally call and say "We see low signal levels - would you mind if we came out and looked at it?" From what I hear, their residential support is nowhere as good.

The first thing you should do is isolate the problem to your network or their network. When you are experiencing the problem, disconnect everything from the LAN port on your cable modem and then plug in a single computer with a direct cable (no switch, etc.). The computer will need to be set to acquire an Internet address via DHCP (it probably is already). Do not power cycle or reset your modem - we'll want to look at some of its data later on.

Now, repeat the tests (speedtest.net, pingtest.net, etc.) and see if you still have the problem. If you do, then it is not on your network. If you don't, then either you have a problem on your network or you just have very bad timing, where the problem cleared while you were switching things over.

If you do still have a problem, you'll want to capture some information from your cable modem. Point your browser to http://192.168.100.1. You should see a page with a Surfboard logo on the top left (since you have a Motorola / Arris modem). There will be tabs along the top. On my modem, they are: Status / Signal / Addresses / Configuration / Logs / Open Source / Help. It may be helpful to take a screen capture of the information (among other things, you can show it to your Comcast tech next time).

We want to look at Signal first. You will see one or more columns for "Downstream". For each column, note the "Signal to Noise Ratio" and "Power Level". These should be relatively consistent across all of the columns (if more than one). Lower on that page you will see one or more columns for "Upstream". Note the "Power Level" in each column there as well. Even further down the page, look for "Signal Stats (Codewords)". We don't care about absolute numbers here, just that for each column "Total Unerrored Codewords" should be a really big number and "Total Correctable Codewords" and "Total Uncorrectable Codewords" should be a lot smaller. For example, in one of my columns I have 10712765113, 616, and 727.

Now, move to the Logs tab and copy all of that data. It is normal for the logs to have some scary-sounding things in them. Rather than try to describe what is bad and what isn't, just post the log here.

Lastly, move to the Help tab. For completeness, copy the info from the top left of the page and paste it here. You may want to x out the serial number - that's fine.

Post that info here and I'll look at it.

Continue reading my next reply for other things you can look at.

 

[Terry Kennedy]

[continued]

You can do some additional testing as well - use the traceroute facility to determine the path between you and the "outside world". On Linux, etc. the command is called traceroute. On Windows, you need to open up a command window (type "cmd" into the start box and click on the cmd.exe it shows you) and the command is called tracert. We'll pick a generic target - ftp.uu.net - for historical reasons. Now type "traceroute ftp.uu.net" (or "tracert ftp.uu.net" if on Windows. You should get something that looks sort of like this (Unix command output, but Windows is similar, but displays times before hostnames/IP addresses):

[0:1] myhost:~> tcptraceroute ftp.uu.net
traceroute to ftp.uu.net (192.48.96.9), 64 hops max, 52 byte packets
1  myhost.example.com (10.20.30.1)  17.934 ms  0.421 ms  0.340 ms
2  96.120.70.109  8.971 ms  8.595 ms *
3  68.85.117.123  23.059 ms  8.504 ms  16.564 ms
4  be-20-ar03.plainfield.nj.panjde.comcast.net (68.85.62.17)  10.803 ms  10.751 ms  10.743 ms
5  he-3-8-0-0-cr01.newyork.ny.ibone.comcast.net (68.86.95.177)  11.672 ms  15.033 ms  11.852 ms
6  he-0-12-0-1-pe03.111eighthave.ny.ibone.comcast.net (68.86.85.86)  15.154 ms  11.302 ms  10.577 ms
7  n-a.GW13.NYC1.ALTER.NET (152.179.220.125)  10.712 ms  21.552 ms  11.290 ms
8  * * *
9  GigabitEthernet6-1.GW3.IAD5.ALTER.NET (152.63.38.1)  21.372 ms  21.745 ms  21.557 ms
10  pos5-0.soesr1.ash.ops.us.uu.net (207.18.173.162)  18.176 ms  18.230 ms  17.867 ms
11  gig1-0.esr-b-10-9-1.ash.ops.us.uu.net (198.5.240.35)  21.413 ms  21.446 ms  21.478 ms
12  gig1-0.esr-b-10-9-1.ash.ops.us.uu.net (198.5.240.35)  19.777 ms !A * 19.796 ms !A

Each of the numbered lines represents one "hop" or step closer to ftp.uu.net. Each hop will have an IP address (#.#.#.#) either at the beginning of the line or in parenthesis to the right. For each one of those, in order from 1 to whatever, use the "ping" command and the IP address. In my case I know that #1 is a piece of equipment at my place that I know is working, so I'd start with:

(0:2) myhost:~> ping 96.120.70.109
PING 96.120.70.109 (96.120.70.109): 56 data bytes
64 bytes from 96.120.70.109: icmp_seq=0 ttl=55 time=15.098 ms
64 bytes from 96.120.70.109: icmp_seq=1 ttl=55 time=14.024 ms
64 bytes from 96.120.70.109: icmp_seq=2 ttl=55 time=14.039 ms
64 bytes from 96.120.70.109: icmp_seq=3 ttl=55 time=13.704 ms
64 bytes from 96.120.70.109: icmp_seq=4 ttl=55 time=14.011 ms
^C
--- 96.120.70.109 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 13.704/14.175/15.098/0.478 ms

On Windows, this will stop by itself. On Linux, etc. you will have to use Control-C to stop it. Look for any missing packets (the "5 packets transmitted, 5 packets received, 0.0% packet loss" part). It is possible for you to interrupt this between when it sends the last request and when the response comes back, so one lost packet at the end is OK.

Repeat this for each hop. So, the next one would be:

ping 68.85.117.123

and so on. Continue until you make it out of Comcast (in the above, that is when the names switch from comcast.net to ALTER.NET).

Problems in the wiring near your house will usually show up in the first few hops - the fiber from the local node (which converts from fiber to coaxial cable) on into the rest of Comcast is usually fine. Sometimes problems happen between Comcast and other providers (like when they were having that spat with Netflix some time ago), but your problem is probably closer to you.

Continued in my next reply.

 

[Terry Kennedy]

[continued]

You should now have an idea about your signal levels and packet loss and will be in better shape to talk to Comcast support. And you'll sound technical enough that they might hand your call off to someone technical, too.

When you talk to the Comcast tech (the support people probably won't tell you), ask them the "node number" your service is on. That's the fiber-to-coax converter I mentioned above. A node may serve only a few blocks in an urban area or a larger area in the suburbs. Being out in the weather, they can become flakey. The node I used to be on (before I got my own) would overheat on summer afternoons when the sun hit it one particular way.

Now that you know your node number, when you call in for support, ask the agent "are there other trouble reports for node xxx?". They might tell you, they might not. If they don't, ask the tech when they come out to investigate your problem report. Multiple complaints on a node mean that there is probably something wrong with the node itself, or (less likely) the fiber from the node deeper into Comcast's network. If there are no other complaints on the node, then the problem is likely somewhere between the pole and your cable modem. Due to the type of coax used between poles ("hard line"), it is probably in the "drop" from the pole to your house, or the lightning protector, splitter (if any), or wiring inside your house. It is occasionally possible for there to be a problem in the splitter in the hard line (on the pole outside or near your house) that your drop connects to, though unlikely.

When they come out, one of the tests they should do is to unscrew the coax from the back of your modem and connect it to their diagnostic box. It will tell them the signal levels and let them do a test for errors ("BERT"). If they don't do that, they're wasting both their time and yours (assuming it isn't something obvious like birds nesting on the pole).

Also ask them if all of the cable on the drop and in your house is the correct kind (the exact type they use varies by region). If older cable was in use for an existing drop when you added Internet service, it may never have been upgraded to the more recent type. Likewise for splitters and (less likely) lightning protectors - they should all be of a type that supports Internet service. Problems here would probably be more continuous than what you are seeing, but it is worth checking. Make sure you can get to (and know where) all of the splitters, etc. are in your house - the tech doesn't have the time to go on a scavenger hunt with you if you haven't already mapped it out. If you are in an apartment building, the cable company is usually required to get the signal into your apartment (stuff outside is their problem). If you are in an apartment, it might be worth talking to the landlord or super ahead of time to ensure the tech can get to any areas where building splitters, etc. might be located.

You have probably had a bunch of service calls by now. You want to keep track of the ticket numbers they give you, and you can then tell support (either phone or the tech when they come out) something like "I've had # trouble tickets for the same problem over the last # months. Can you please perform an extended monitoring on my service?" That will (if they do it) have their test equipment continually watch your line to catch any problems when they happen. If the problem doesn't happen all the time, that is probably the only way they will be cable to catch it.

 

[Terry Kennedy]

Don't you just hate it when you compose a long series of detailed replies to someone who turns out to be a hit-and-run poster who never came back after posting their question?

 

[istari675]

Oh sorry, I thought that all was just a copy/paste. The issue stopped on its own, but I stayed subscribed to this thread in case it comes back so I can do the steps you suggested. Thank you for all the effort you put into helping me and im sure I will use it once this issue shows up again.

 

[Terry Kennedy]

Oh sorry, I thought that all was just a copy/paste.

Nope, composed just for you.

The issue stopped on its own, but I stayed subscribed to this thread in case it comes back so I can do the steps you suggested. Thank you for all the effort you put into helping me and im sure I will use it once this issue shows up again.

Well, this would be a good time to look at your upstream/downstream signal levels and ratio of good to correctable/uncorrectable codewords, so you will know what things look like when it is working and compare them with what happens when it isn't working properly.