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Rakeesh
join:2011-10-30
Phoenix, AZ

Rakeesh

Member

[AZ] Any other broadband choices out here?

I think I've finally had it, I'm sick of having to power cycle my modem all the time because it stops responding to the network. I keep calling Cox to try to sort it out but they seem rather disinterested in solving the problem, whatever is causing it. (They keep blaming it on my equipment even though I've tried three different routers and three different cable modems. I suspect the problem has to do with when the cable modem needs to switch frequencies, but the logs are insufficient to determine.)

Anyways, is there anything out here besides cox and centurystink that I might not be aware of yet? No wireless unless its some kind of point-to-point without a low cap.
m8trix
join:2003-12-24
Chandler, AZ

1 recommendation

m8trix

Member

when was the last time you had a tech out

antonio010
join:2002-11-24

antonio010 to Rakeesh

Member

to Rakeesh
Nothing until you're further east then you have the option of Mediacom.

Your best bet is to involve Cox tech support. Get it escalated.
Rakeesh
join:2011-10-30
Phoenix, AZ

Rakeesh

Member

said by antonio010:

Nothing until you're further east then you have the option of Mediacom.

Your best bet is to involve Cox tech support. Get it escalated.

How far east are we talking? I'm in very far East Mesa.

odog
Minister of internet doohickies
Premium Member
join:2001-08-05
Atlanta, GA
Nokia BGW320-505

odog to Rakeesh

Premium Member

to Rakeesh
Can you something a bit unorthodox?

Clone your routers external MAC address into your computer. Or vice versa, so that the computer and the router have the same CPE MAC. Next time it happens plug in to the modem directly and do a release/renew, hopefully you'll get on.

Like you've said before, the modem says it is working fine right up until you power cycle it.

Also try setting up concurrent pings to these, and hopefully you'll catch it happen.

inside of router 192.168.0.1 (or whatever your NAT'd default gateway is)
inside of CM 192.168.100.1
first hop use tracert to find the first 10.0.0.0 IP.

antonio010
join:2002-11-24

antonio010 to Rakeesh

Member

to Rakeesh
said by Rakeesh:

How far east are we talking? I'm in very far East Mesa.

I would say closer to the unincorporated areas of east Mesa. Then all of AJ and most of Queen Creek/San Tan Valley.
Rakeesh
join:2011-10-30
Phoenix, AZ

Rakeesh to odog

Member

to odog
said by odog:

Can you something a bit unorthodox?

Clone your routers external MAC address into your computer. Or vice versa, so that the computer and the router have the same CPE MAC. Next time it happens plug in to the modem directly and do a release/renew, hopefully you'll get on.

Like you've said before, the modem says it is working fine right up until you power cycle it.

Also try setting up concurrent pings to these, and hopefully you'll catch it happen.

inside of router 192.168.0.1 (or whatever your NAT'd default gateway is)
inside of CM 192.168.100.1
first hop use tracert to find the first 10.0.0.0 IP.

I'll try it after the next time it happens (tech came out and just replaced a bunch of cable on my side of the drop as a troubleshooting measure.)

Though when this happens, the CMTS side can't see the modem; it's as if it were powered off (so the other person on the phone says.) However it does respond to a CMTS issued reset, which temporarily resolves the issue until it happens again.
Ameth
join:2011-07-20

Ameth to Rakeesh

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to Rakeesh
whats the model number of your modem?
Rakeesh
join:2011-10-30
Phoenix, AZ

Rakeesh

Member

said by Ameth:

whats the model number of your modem?

Motorola SB6141.

Just had another tech come out Thursday, this time it was a senior tech. He said he's seen this exact problem before with the SB6141 and the only fix was to replace with a different model.

I don't want to speak prematurely, but I put the old Cisco modem back, and the issues it once had seem to be gone (probably as a result of the old wiring being replaced.) I'll report back after a week, but the typical times that it's supposed to either crash or (in past times with the Cisco modem) have high latency have had no problems so far (the SB6141 never stopped having this crash problem though.)

I suspect the culprit is a firmware bug in the SB6141. Since it is an intermittent problem that obviously only affects very few uses, I don't expect we'll see an update to fix it within this lifetime.

odog
Minister of internet doohickies
Premium Member
join:2001-08-05
Atlanta, GA

odog

Premium Member

I'd be interested to hear what he thought the SB6141 problem was? PM his name if you remember it, I'd like to ask him about it.

What model Cisco modem are you using now?

bbeesley
join:2003-08-07
Richardson, TX

bbeesley to Rakeesh

Member

to Rakeesh
said by Rakeesh:

the CMTS side can't see the modem....However it does respond to a CMTS issued reset

That's incongruous. If the CMTS can't "see the modem" then it can't send an SNMP command to make it reset.

based on what odog said, the modem is alive and logging up until you power cycel it so you need to troubleshoot elsewhere and not just assume the modem is the cause
Rakeesh
join:2011-10-30
Phoenix, AZ

1 edit

Rakeesh

Member

said by bbeesley:

said by Rakeesh:

the CMTS side can't see the modem....However it does respond to a CMTS issued reset

That's incongruous. If the CMTS can't "see the modem" then it can't send an SNMP command to make it reset.

based on what odog said, the modem is alive and logging up until you power cycel it so you need to troubleshoot elsewhere and not just assume the modem is the cause

My personal theory is that its layer 3 software stack has crashed. I came to this theory because using tcpdump I could see ethernet frames coming and going (I don't recall what all they were, and I've since discarded the dumps) meanwhile nothing else responds.

I don't know how the reset command is sent from the CMTS end (I don't know docsis) but I have a feeling that it isn't much more complicated than an ethernet frame containing the modem's mac address and a simple instruction to reset. In which case, the cable modem doesn't need layer 3 functionality, indeed it doesn't even need to reply to the command, rather it simply needs to do as its told. I may be wrong, but I don't believe that particular function is SNMP driven. It would make sense for it not to be.

Odog, I figure you'd know, could you chime in on this one?

Which by the way, if tcpdump is working on my router and is actively sending data to wireshark, then I'd like to hear how you think the router is having the problem during these times? (There really is no other point that I can troubleshoot; I can't control anything past the WAN port of my router.)

In any case, since switching back to the Cisco modem I haven't yet seen any problems. Sunday nights I would ALWAYS see problems with the SB6141, yet last Sunday everything was working fine.
Rakeesh

Rakeesh to odog

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to odog
said by odog:

I'd be interested to hear what he thought the SB6141 problem was? PM his name if you remember it, I'd like to ask him about it.

What model Cisco modem are you using now?

Cisco DPC-3000. You've got PM.

bbeesley
join:2003-08-07
Richardson, TX

bbeesley to Rakeesh

Member

to Rakeesh
said by Rakeesh:

how the reset command is sent from the CMTS end (I don't know docsis) but I have a feeling that it isn't much more complicated than an ethernet frame containing the modem's mac address

first, the CMTS and modem are using DOCSIS at layer 2, not Ethernet. The modem acts as a bridge between your Ethernet network and the DOCSIS network

the reset is sent via SNMP - layer 3 to the modem's IP addy

here is some PHP to show you how it works »docsis.org/node/9

here is a complete list of DOCSIS MIBs in case you are curious as to what all can be done via SNMP »www.oidview.com/mibs/0/D ··· MIB.html
Rakeesh
join:2011-10-30
Phoenix, AZ

Rakeesh

Member

said by bbeesley:

said by Rakeesh:

how the reset command is sent from the CMTS end (I don't know docsis) but I have a feeling that it isn't much more complicated than an ethernet frame containing the modem's mac address

first, the CMTS and modem are using DOCSIS at layer 2, not Ethernet. The modem acts as a bridge between your Ethernet network and the DOCSIS network

I figured that much (I suspected docsis itself was a layer 2 protocol but never researched it; I honestly know didly about docsis) but isn't it a separate network? e.g. I can't send an ethernet frame to my cable modem containing the mac address of somebody else's cable modem and expect my cable modem to forward it as a docsis frame?

Anywho, are you sure that is the only means that the cable co can issue a reset? I'm telling you this actually happened multiple times, they COULD NOT SEE the modem, yet sending a reset from their end worked.

bbeesley
join:2003-08-07
Richardson, TX

bbeesley

Member

said by Rakeesh:

this actually happened multiple times, they COULD NOT SEE the modem

yeah...I've seen techs make specious statements multiple times too. I just got off the phone with a friend in Oklahoma who was told that the reason his modem was pulling things slow off the Internet was that he just got it and it had not been activated.

clearly, if he was surfing the Internet his modem was activated and indeed, the person at the Cox store had activated it for him

Hard Harry7
join:2010-10-19
Narragansett, RI

Hard Harry7

Member

If I had to guess, the tool the representative was using was having a hard time communicating with the modem and errored out, giving the impression that the modem was offline. I have had times where Cox has told me "I can't see your modem" while I am standing there, using it to talk to that representative, since it a phone modem.
Maltz
join:2011-01-08
Fayetteville, AR
Calix 844G
Netgate SG-2100
Ubiquiti U6-LR

Maltz to bbeesley

Member

to bbeesley
said by bbeesley:

yeah...I've seen techs make specious statements multiple times too. I just got off the phone with a friend in Oklahoma who was told that the reason his modem was pulling things slow off the Internet was that he just got it and it had not been activated.

clearly, if he was surfing the Internet his modem was activated and indeed, the person at the Cox store had activated it for him

Actually... that is a thing. Depending on how slow we're talking, anyway.

I had a friend who got a new DOCSIS 3 4x4 channel modem to replace his old DOCSIS 2 modem. He was on premier and should have been getting 50Mb+ with the new modem after we went through the self-activation process. But the evening we first hooked it up, he only got 35Mb. I figured the bottleneck was probably now his older router. A few days later I checked again, and sure enough, he was now topping out at 65Mb on the speed test. I later heard that Cox may provision DOCSIS 2 and 3 modems differently, so I assume the new modem was originally provisioned at the lower speed of the modem it replaced and that the nightly firmware update etc. routine re-provisioned it for the higher speed. (Thankfully, I saw that before he went a bought a new router. lol)

That said, I HAVE heard techs spout total nonsense though. Usually in an attempt to ensure the customer actually does what they ask them to do. Having been on both sides of that conversation, I can't really blame them. And sometimes, the most knowledgable customers are the worst because we assume we've covered the simple things. Support rep: "Is it plugged in?" Offended customer: "YES! I'm not an idiot!!" 20 minutes later... sheepish customer: "Oh, look at that. It wasn't plugged in. thanksbye" So instead they ask you to unplug and replug to reset the IP connection to the tachyon collector or some such. lol

It's also possible they understand the what but not the why and are just guessing about that part. I always comply anyway because A) it forces me to check something simple I might have overlooked, and B) it might actually have an effect that I, and possibly the support rep, are not aware of. The rep might not understand all the nuances of the system, and I sure don't, but whoever wrote the troubleshooting script they're following probably had a pretty good handle on it.

bbeesley
join:2003-08-07
Richardson, TX

bbeesley

Member

said by Maltz:

Cox may provision DOCSIS 2 and 3 modems differently

in this instance, the good folks at the service center where he bought the modem made a point to provision it before he left to avoid such things

his issue was actually a short piece of cable between a tap and his house amp that a tech tried to stuff back into a J-box, kinking it

the cable was likely causing microreflections due to the impedance mismatch from the kink and the house amp was amplifying it, raising the noise floor in his house and causing his modem and set-tops to be very, very unhappy

he replaced the cable and voila!....all was well