# Solved: Downstream Channel Bonding Problem



## Darkicon (Feb 12, 2008)

About 7 months ago I upgraded to TWC Roadrunner 40/5mbps which required me to upgrade to a DOCSIS 3 modem. Unfortunately, at the time all DOCSIS 3 (That weren't super expensive) were only sold to ISPs so I had to rent from TWC. They gave me an Arris Touchstone TG862.

I now have it in bridge mode due to not liking TWC's extreme policing policies on using rental modems/routers if you're not a Signature subscriber and the router portion didn't support dual-channel and I wanted it. So I switched over to my old Linksys EA2700 router.

However, I am having an issue with downstream channel bonding. The modem used to bond to all 4 channels, now it only bonds to 2 channels. My SNR and power levels are all well within acceptable ranges and I bond to all 4 channels upstream. When the modem was new, it was always bonded to 4 channels, and it started only bonding to 2 and occasionally bonding to a 3rd every once in awhile but quickly dropping it a month or two ago (Before I threw it into bridge). I also have a lot of FEC errors on downstream with a pretty high ratio of uncorrectables to correctables. Unfortunately, I'm not at home right now and the only way to access the modem's HSD diagnostics is to directly connect to it (Downside of bridge mode on this modem). The error log has many RCS partial service and lost MMD timeout events. Many every minute.

I've noticed, starting a few days ago, every once in awhile my connection speed would flatline at about 0.75mbps for 5-10 minutes before regaining full 40mbps with upload remaining at the full 5mpbs. Never fully dropping out, just getting very slow.

Is the slow speed due to the channel bonding issue even though I haven't noticed slow speeds that often prior to a few days ago? Tomorrow I'm gonna try to chat with a level 3 TWC tech, find out who's end the problems is on. Just wanted to see what you guys think. Thanks.


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## Couriant (Mar 26, 2002)

If your modem does not channel bond, then you may end up about 10Mbps. If your modem GUI shows 1 or 2 downstreams then all of the data is going on those one/two.

The bonding issue is either the fault of the modem or the fault of the CMTS (the server it's connecting to). Generally the latter.

What confuses me is that you are seeing more upstream channels than downstream when it's usually 4 downstreams and 2 upstreams. A screenshot would be nice 

Do you have TWC's phone service too? Can they provide you with a TM722G, or TM802G modem instead?


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## Darkicon (Feb 12, 2008)

http://imageshack.com/a/img837/940/qsqx.png
http://imageshack.com/a/img844/224/x4ed.png
http://imageshack.com/a/img844/2883/q9d9.png

Today I swapped out my modem for a new one, unfortunately, I could only get the Ubee/Ambit DVW3201B. Tried to specify but they handed me this one regardless. Appears to have the same downstream bonding problem. Also, after watching the diagnostics, I've noticed channel 3's SNR fluctuates quite a bit. From 27dB (When the channel cuts out) to about 32dB. while the other channels are usually around 36-38dB.

It appears my connectivity issue hasn't been fixed with the changeout. Now I'm seeing about 10mbps. Better than the .75mbps I was seeing all yesterday and last night but still far from my 40mbps. Unfortunately, my networking experience from college is super old and useless now, lol.

Before doing the changeout, I monitored the FEC error rate on my Arris and 10 minutes after resetting the counter, I had 1.6m correctables and 1.4m uncorrectables on channel 3, while 1&2 had 0 FEC errors after 10 minutes. Oh and yes, I also have a landline through TWC.


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## Couriant (Mar 26, 2002)

anything below 28dB is generally a possible issue. Since you are not channel bonding on 4 channels I suspect that the CMTS (server at head end) is not channel bonding correctly for this modem. I would suggest calling them to get this escalated to their engineers. However this:

_I monitored the FEC error rate on my Arris and 10 minutes after resetting the counter, I had 1.6m correctables and 1.4m uncorrectables on channel 3_

It sounds like all the traffic is going on that channel and majority are failing, which will cause speed issues. I suspect the issue is on the head end.


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## Darkicon (Feb 12, 2008)

Okay, thank you. I will get a hold of TWC techs as soon as possible.


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## Couriant (Mar 26, 2002)

:up: any news?


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## Darkicon (Feb 12, 2008)

Took me a couple of days to get their attention but finally after 2 chat sessions and 2 phone calls, a tech ran the loopback diagnostic and identified the problem as my wiring. I replaced with a brand new home run with a brand new RG8 coax, brand new compression-fit F-connectors and a brand new 3GHz grounding block and now all channels bond, SNR never moves from 40dB and no more FEC errors. I was extremely surprised when they offered to schedule a tech same-day. They usually schedule a month or two ahead. But I'd rather replace it all myself, I don't know what quality cable or connectors they use.

I checked my wires before but I guess I forgot to check one splitter and it was the one that was pretty corroded but now I don't use any splitters, just a dedicated run from the grounding block to the CM (I use satellite for TV).


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## Couriant (Mar 26, 2002)

:up: good to hear they finally found the problem ... from us...


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