Comments on: DOCSIS and Cable Modems – How it works :: Station Maintenance http://volpefirm.com/docsis-101/docsis101_station-maintenance/ A Technical Communications Company Wed, 16 May 2012 06:51:01 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: D.J. http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-348 D.J. Wed, 02 May 2012 21:39:10 +0000 http://bradyvolpe.com/?p=245#comment-348 I have to agree with you that many of the name brand modem vendors have had issues with firmware for Docsis 3.0 modems. Our company has seen issues with many different brands. I have to agree with you that many of the name brand modem vendors have had issues with firmware for Docsis 3.0 modems. Our company has seen issues with many different brands.

]]> By: Douglas Courchaine http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-180 Douglas Courchaine Tue, 13 Mar 2012 16:00:44 +0000 http://bradyvolpe.com/?p=245#comment-180 Brady, Thank you sir! Brady,

Thank you sir!

]]> By: Brady http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-179 Brady Tue, 13 Mar 2012 13:42:08 +0000 http://bradyvolpe.com/?p=245#comment-179 Hi Douglas, I have just completed some pretty detailed testing of a number of different vendors of DOCSIS 3.0 cable modems. I am pretty shocked at how poorly some brand name modems performed in my testing. These are companies you would not expect to have any problems at all, but I fought with them to stay online. So to see a subscriber as yourself experiencing similar problems with DOCSIS 3.0 modems does not surprise me. You are not alone and the reason is that DOCSIS 3.0 is new enough that the DOCSIS 3.0 cable modem firmware has not been completely de-bugged by the manufacturers. Since I don't know the configuration of the Cox DOCSIS plant, I am only speculating as to your possible problem. There is one message that looks like it could be the cause of the problem, although this may just be a symptom. <strong>Tue Mar 6 08:54:52 2012 Error (4) DCC-ACK not received;CM-MAC=removed CMTS-MAC=68:ef:…</strong> This is showing that the CMTS is trying to move the DOCSIS 3.0 cable modem to a different channel and your cable modem is not listening. I believe that is a bug with the cable modem firmware. What I don't know is why the CMTS is telling the cable modem to move. Maybe its moving the cable modem for load balancing (because there are too many cable modems on that CMTS) or maybe its moving the DOCSIS 3.0 cable modem to a DOCSIS 3.0 CMTS. Again, I have no way of knowing, but your cable modem appears to not be listening and so the CMTS is black-listing the cable modem into what is known as a "flap-list". When Cox installed a DOCSIS 3.0 modem that they knew worked fine your problems went away. This was the right solution. As I found in my own lab, I had to do special things for some modems in order to make them work. In another year or so the cable modem vendors will likely fix their problems. -Brady Hi Douglas,

I have just completed some pretty detailed testing of a number of different vendors of DOCSIS 3.0 cable modems. I am pretty shocked at how poorly some brand name modems performed in my testing. These are companies you would not expect to have any problems at all, but I fought with them to stay online. So to see a subscriber as yourself experiencing similar problems with DOCSIS 3.0 modems does not surprise me. You are not alone and the reason is that DOCSIS 3.0 is new enough that the DOCSIS 3.0 cable modem firmware has not been completely de-bugged by the manufacturers.

Since I don’t know the configuration of the Cox DOCSIS plant, I am only speculating as to your possible problem. There is one message that looks like it could be the cause of the problem, although this may just be a symptom.

Tue Mar 6 08:54:52 2012 Error (4) DCC-ACK not received;CM-MAC=removed CMTS-MAC=68:ef:…

This is showing that the CMTS is trying to move the DOCSIS 3.0 cable modem to a different channel and your cable modem is not listening. I believe that is a bug with the cable modem firmware. What I don’t know is why the CMTS is telling the cable modem to move. Maybe its moving the cable modem for load balancing (because there are too many cable modems on that CMTS) or maybe its moving the DOCSIS 3.0 cable modem to a DOCSIS 3.0 CMTS. Again, I have no way of knowing, but your cable modem appears to not be listening and so the CMTS is black-listing the cable modem into what is known as a “flap-list”.

When Cox installed a DOCSIS 3.0 modem that they knew worked fine your problems went away. This was the right solution. As I found in my own lab, I had to do special things for some modems in order to make them work. In another year or so the cable modem vendors will likely fix their problems.

-Brady

]]> By: Douglas Courchaine http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-178 Douglas Courchaine Mon, 12 Mar 2012 19:19:58 +0000 http://bradyvolpe.com/?p=245#comment-178 Mr. Brady, I'm here asking for your help with a problem I've of late been experiencing with my cable internet service. I've googled and there seems to be, and possibly has been for some time, an epidemic that is affecting cable internet subscribers across the USA. Possibly wherever cable internet is offered. I've attached the most recent modem log that I have. Been with my isp for many years. A few months ago, this problem started happening. Modem seems to reboot, as it were. Replaced modem thinking it was just outdated (sb5120), which it was. Same issues with the new modem (netgear cmd31t). My isp sent a tech with a cisco modem DPC3010, which has been running flawlessly. This should, and does for the most part, make me happy. Still, there is a part of me that "needs" to know why a problem just appears, and just as mysteriously, disappears. Any help you can give is appreciated. I'm in the greater Phoenix area. Cox has the monopoly on cable service here. Other than the recent problem, I think they're great. Tue Mar 6 08:54:51 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Tue Mar 6 08:54:52 2012 Error (4) DCC-ACK not received;CM-MAC=removed CMTS-MAC=68:ef:... Tue Mar 6 08:54:54 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Tue Mar 6 08:55:07 2012 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=removed... Tue Mar 6 08:55:37 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un... Tue Mar 6 08:56:00 2012 Critical (3) Unicast Ranging Received Abort Response - initializing MAC;CM... Tue Mar 6 08:56:34 2012 Warning (5) ToD request sent - No Response received;CM-MAC=removed... Tue Mar 6 08:56:35 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=removed;CMTS-MAC=6... Tue Mar 6 08:56:35 2012 Warning (5) RCS Partial Service;CM-MAC=removed;CMTS-MAC=removed... Tue Mar 6 09:15:14 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Tue Mar 6 09:15:14 2012 Error (4) DCC-ACK not received;CM-MAC=removed;CMTS-MAC=removed... Tue Mar 6 09:15:16 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Tue Mar 6 09:15:30 2012 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=removed... Tue Mar 6 09:16:00 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un... Tue Mar 6 09:16:26 2012 Critical (3) Unicast Ranging Received Abort Response - initializing MAC;CM... Tue Mar 6 09:17:00 2012 Warning (5) ToD request sent - No Response received;CM-MAC=removed... Tue Mar 6 09:17:01 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=removed;CMTS-MAC=removed... Tue Mar 6 13:52:48 2012 Critical (3) SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=removed... Tue Mar 6 13:52:52 2012 Warning (5) Lost MDD Timeout;CM-MAC=removed;CMTS-MAC=removed... Time Not Established Warning (5) ToD request sent - No Response received;CM-MAC=removed... Wed Mar 7 18:38:58 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=removed;CMTS-MAC=removed... Time Not Established Warning (5) ToD request sent - No Response received;CM-MAC=removed... Wed Mar 7 19:05:22 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=removed;CMTS-MAC=removed... Time Not Established Warning (5) ToD request sent - No Response received;CM-MAC=removed... Wed Mar 7 21:03:51 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=removed;CMTS-MAC=removed... Wed Mar 7 21:11:53 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Wed Mar 7 21:11:54 2012 Error (4) DCC-ACK not received;CM-MAC=removed;CMTS-MAC=removed... Wed Mar 7 21:11:56 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Wed Mar 7 21:12:09 2012 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=removed... Wed Mar 7 21:12:39 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un... Wed Mar 7 21:13:02 2012 Critical (3) Unicast Ranging Received Abort Response - initializing MAC;CM... Wed Mar 7 21:13:36 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=2c:b0:5d:57:d8:70;CMTS-MAC=6... Wed Mar 7 21:27:12 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Wed Mar 7 21:27:12 2012 Error (4) DCC-ACK not received;CM-MAC=removed;CMTS-MAC=removed... Wed Mar 7 21:27:14 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - ... Wed Mar 7 21:27:27 2012 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=removed... Wed Mar 7 21:27:57 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un... Wed Mar 7 21:28:20 2012 Critical (3) Unicast Ranging Received Abort Response - initializing MAC;CM... Wed Mar 7 21:28:52 2012 Warning (5) ToD request sent - No Response received;CM-MAC=removed... Wed Mar 7 21:28:53 2012 Notice (6) TLV-11 - unrecognized OID;CM-MAC=removed;CMTS-MAC=removed... Sorry to bother you with this. Mr. Brady,
I’m here asking for your help with a problem I’ve of late been experiencing with my cable internet service. I’ve googled and there seems to be, and possibly has been for some time, an epidemic that is affecting cable internet subscribers across the USA. Possibly wherever cable internet is offered.

I’ve attached the most recent modem log that I have.

Been with my isp for many years. A few months ago, this problem started happening. Modem seems to reboot, as it were.

Replaced modem thinking it was just outdated (sb5120), which it was. Same issues with the new modem (netgear cmd31t).

My isp sent a tech with a cisco modem DPC3010, which has been running flawlessly.

This should, and does for the most part, make me happy. Still, there is a part of me that “needs” to know why a problem just appears, and just as mysteriously, disappears.

Any help you can give is appreciated. I’m in the greater Phoenix area. Cox has the monopoly on cable service here. Other than the recent problem, I think they’re great.

Tue Mar 6 08:54:51 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Tue Mar 6 08:54:52 2012 Error (4) DCC-ACK not received;CM-MAC=removed CMTS-MAC=68:ef:…
Tue Mar 6 08:54:54 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Tue Mar 6 08:55:07 2012 Critical (3) No Ranging Response received – T3 time-out;CM-MAC=removed…
Tue Mar 6 08:55:37 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un…
Tue Mar 6 08:56:00 2012 Critical (3) Unicast Ranging Received Abort Response – initializing MAC;CM…
Tue Mar 6 08:56:34 2012 Warning (5) ToD request sent – No Response received;CM-MAC=removed…
Tue Mar 6 08:56:35 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=removed;CMTS-MAC=6…
Tue Mar 6 08:56:35 2012 Warning (5) RCS Partial Service;CM-MAC=removed;CMTS-MAC=removed…
Tue Mar 6 09:15:14 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Tue Mar 6 09:15:14 2012 Error (4) DCC-ACK not received;CM-MAC=removed;CMTS-MAC=removed…
Tue Mar 6 09:15:16 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Tue Mar 6 09:15:30 2012 Critical (3) No Ranging Response received – T3 time-out;CM-MAC=removed…
Tue Mar 6 09:16:00 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un…
Tue Mar 6 09:16:26 2012 Critical (3) Unicast Ranging Received Abort Response – initializing MAC;CM…
Tue Mar 6 09:17:00 2012 Warning (5) ToD request sent – No Response received;CM-MAC=removed…
Tue Mar 6 09:17:01 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=removed;CMTS-MAC=removed…
Tue Mar 6 13:52:48 2012 Critical (3) SYNC Timing Synchronization failure – Loss of Sync;CM-MAC=removed…
Tue Mar 6 13:52:52 2012 Warning (5) Lost MDD Timeout;CM-MAC=removed;CMTS-MAC=removed…
Time Not Established Warning (5) ToD request sent – No Response received;CM-MAC=removed…
Wed Mar 7 18:38:58 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=removed;CMTS-MAC=removed…
Time Not Established Warning (5) ToD request sent – No Response received;CM-MAC=removed…
Wed Mar 7 19:05:22 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=removed;CMTS-MAC=removed…
Time Not Established Warning (5) ToD request sent – No Response received;CM-MAC=removed…
Wed Mar 7 21:03:51 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=removed;CMTS-MAC=removed…
Wed Mar 7 21:11:53 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Wed Mar 7 21:11:54 2012 Error (4) DCC-ACK not received;CM-MAC=removed;CMTS-MAC=removed…
Wed Mar 7 21:11:56 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Wed Mar 7 21:12:09 2012 Critical (3) No Ranging Response received – T3 time-out;CM-MAC=removed…
Wed Mar 7 21:12:39 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un…
Wed Mar 7 21:13:02 2012 Critical (3) Unicast Ranging Received Abort Response – initializing MAC;CM…
Wed Mar 7 21:13:36 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=2c:b0:5d:57:d8:70;CMTS-MAC=6…
Wed Mar 7 21:27:12 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Wed Mar 7 21:27:12 2012 Error (4) DCC-ACK not received;CM-MAC=removed;CMTS-MAC=removed…
Wed Mar 7 21:27:14 2012 Critical (3) Started Unicast Maintenance Ranging – No Response received – …
Wed Mar 7 21:27:27 2012 Critical (3) No Ranging Response received – T3 time-out;CM-MAC=removed…
Wed Mar 7 21:27:57 2012 Critical (3) Received Response to Broadcast Maintenance Request, But no Un…
Wed Mar 7 21:28:20 2012 Critical (3) Unicast Ranging Received Abort Response – initializing MAC;CM…
Wed Mar 7 21:28:52 2012 Warning (5) ToD request sent – No Response received;CM-MAC=removed…
Wed Mar 7 21:28:53 2012 Notice (6) TLV-11 – unrecognized OID;CM-MAC=removed;CMTS-MAC=removed…

Sorry to bother you with this.

]]> By: Murali Krishna Bheemineni http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-177 Murali Krishna Bheemineni Mon, 12 Mar 2012 07:12:40 +0000 http://bradyvolpe.com/?p=245#comment-177 This is the great blog to understand the DOCSIS basics. I would like to Thank Brady for spending his valuable time for explaining the stuff which you can't understand so easily from DOCSIS specification. Great work Brady. This is the great blog to understand the DOCSIS basics.

I would like to Thank Brady for spending his valuable time for explaining the stuff which you can’t understand so easily from DOCSIS specification.

Great work Brady.

]]> By: Impact of Impulse Noise on Adaptive Pre-Equalization Part II | bradyvolpe.com http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-176 Impact of Impulse Noise on Adaptive Pre-Equalization Part II | bradyvolpe.com Thu, 01 Mar 2012 19:12:31 +0000 http://bradyvolpe.com/?p=245#comment-176 [...] message to the cable modem.  This is the station maintenance process, also further detailed in the Station Maintenance [...] [...] message to the cable modem.  This is the station maintenance process, also further detailed in the Station Maintenance [...]

]]> By: bradyvolpe.com | Impulse Noise and Adaptive Pre-Equalization | bradyvolpe.com http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-175 bradyvolpe.com | Impulse Noise and Adaptive Pre-Equalization | bradyvolpe.com Wed, 29 Feb 2012 20:13:23 +0000 http://bradyvolpe.com/?p=245#comment-175 [...] enabled adaptive pre-equalization.  When the command was enabled, the CMTS started looking at the RNG-REQ messages coming from each cable modem.  The CMTS analyzes the quality of the RNG-REQ message and [...] [...] enabled adaptive pre-equalization.  When the command was enabled, the CMTS started looking at the RNG-REQ messages coming from each cable modem.  The CMTS analyzes the quality of the RNG-REQ message and [...]

]]> By: Brady http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-174 Brady Mon, 16 Jan 2012 17:21:22 +0000 http://bradyvolpe.com/?p=245#comment-174 Hi MZee, There could be a number of reasons that a certain MAC address may range one time, then be rejected and fail to range later. My first recommendation is to check the CMTS flap list and see if the MAC address is on it and what information is listed on the flap list. Sometimes the problem may be simple like the modem does not have enough transmit power, which is an RF plant issue. However if you have a "cloned" modem problem, then putting the MAC address on reject list will also impact the paying subscriber. A better method is to use EAE (Early Authentication Encryption) on DOCSIS 3.0 systems in combination with Fraud Prevention modules added to your provisioning system. -Brady Hi MZee,

There could be a number of reasons that a certain MAC address may range one time, then be rejected and fail to range later. My first recommendation is to check the CMTS flap list and see if the MAC address is on it and what information is listed on the flap list. Sometimes the problem may be simple like the modem does not have enough transmit power, which is an RF plant issue. However if you have a “cloned” modem problem, then putting the MAC address on reject list will also impact the paying subscriber. A better method is to use EAE (Early Authentication Encryption) on DOCSIS 3.0 systems in combination with Fraud Prevention modules added to your provisioning system.

-Brady

]]> By: MZee http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-173 MZee Tue, 03 Jan 2012 14:11:01 +0000 http://bradyvolpe.com/?p=245#comment-173 Hi Brady. Is it possible to block certain MAC addresses from Ranging. I have an experience that a MAC works for few minutes fine but later on it never passes through Ranging status. Is it due to cloning of MAC from different node? Hi Brady.
Is it possible to block certain MAC addresses from Ranging. I have an experience that a MAC works for few minutes fine but later on it never passes through Ranging status. Is it due to cloning of MAC from different node?

]]> By: Brady http://volpefirm.com/docsis-101/docsis101_station-maintenance/#comment-172 Brady Tue, 22 Nov 2011 11:28:12 +0000 http://bradyvolpe.com/?p=245#comment-172 Ken, You are absolutely correct. Most respected CMTSs with updated processing platforms and IOSs that you buy today will ensure that the RNG-RSP is prioritized in a timely manner. That being said, I have seen my share of out-dated IOSs and under-scaled processing engines running in large systems. When you look at the stats you see a long history of 99% utilization. It is a challenging discussion to have that some of the challenges in the system may not all be RF related and the fix is going to cost CAPEX money, none of which I take any commission on, BTW. ;-) -Brady Ken,

You are absolutely correct. Most respected CMTSs with updated processing platforms and IOSs that you buy today will ensure that the RNG-RSP is prioritized in a timely manner. That being said, I have seen my share of out-dated IOSs and under-scaled processing engines running in large systems. When you look at the stats you see a long history of 99% utilization. It is a challenging discussion to have that some of the challenges in the system may not all be RF related and the fix is going to cost CAPEX money, none of which I take any commission on, BTW. ;-)

-Brady

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