Since 1st August we've been having regular drop outs of our connection, sometimes I've had to reboot the SH3, sometimes I've gone to it and seen it's connecting (green internet lights on) so I know it's just negotiated a connection. The CM sends a ranging request (RNG-REQ) message to the CMTS and waits for a ranging response (RNG-RSP) message or a T3 timer expiration. To learn why the GI upconverters use this frequency read Cable Radio Frequency (RF) FAQ (registered customers only) . Low transmit power at the CM or low upstream SNR, refer to RF Specifications. Problems getting Time of Day (TOD) or Timing Offset would also result in modem not achieving online status: Note: Prior to Cisco IOS Software Release version 12.1(1) TOD needed to be specified in the DHCP server in order for the Cable Modem to go online. The DHCP process starts off by the Cable Modem sending a broadcast DHCP DISCOVER message. The DHCP server can respond with an acknowledged (ACK) or not acknowledged (NAK). Another common mistake is to specify an incorrect frequency value in the Downstream Frequency field under the Radio Frequency Info in the DOCSIS CPE Configurator. ‎07-11-2018 The commands are: Some of the commands that can be used to debug ToD problems when the CMTS is configured as the ToD are show cable clock, show controllers clock-reference. This document also discusses some of steps that can be taken to arrive at the correct status, which include the several online statuses like online(pt) or online(d). Note: For correct BPI operation ensure that the CMTS and CM are both running a BPI enabled image, which is signified by the symbol K1 in the image name. However, after Cisco IOS Software Release version 12.1(1) TOD is not required but the Cable Modem still needs to get the timing offset, as shown in the following debugs: In the debugs below we have no time-server specified but we have a timing offset configured in the DHCP server hence the Cable Modem going online: For a comprehensive list of what DHCP options are required and which ones are optional please refer to DHCP and the DOCSIS Configuration File for Cable Modems (DOCSIS 1.0) tech note. Thus, broadcast ranging is contention based and subject to collisions. I'm sorry to read you are experiencing intermittent connection. on You may need to select another frequency in the spectrum if a particular frequency has too much noise present. It directly controls the length of time to recover the network. Below we have Cable Modems with SID 1 and 2 in init(t). The time to wait for a station maintenance interval to perform station maintenance ranging. The main configuration and administration interface to the cable modem is the configuration file downloaded from the provisioning server. Forum discussion: How do these look? MAybe we need to swap this modem out? If a T3 timeout occurs, the retry count increments. Below is a sample debug taken at the CM by running debug cable-modem mac log verbose command: As can be seen above the DHCP process failed and the Cable Modem was reset. This is likely to be a headend misconfiguration. From the output display of show cable modem command above we have four modems in the offline state. This website uses cookies. Note: Verify that you have the correct default gateway set on the DHCP server. Below output shows CM with SID 6 in init(r1) state indicating the CM cannot get past the initial ranging stage: The debug below shows how the CM fails to complete the ranging process and resetting after a T3 timer expiration and number of retries exceeded. Notice that cable modems with SID 97, 99, and 100 use port upstream 0 while the rest of the cable modems use telco return for the upstream path. 17:53. hijacking someone else's thread isn't the done thing... on Sign in for the easiest way to view and pay your bill, manage your account, watch TV anywhere and more. Reset the modem with a paperclip. The following list gives the most common reasons for a modem not able to achieve quadrature amplitude modulation(QAM) lock: The Cable Modem is not connected to the network or it is not turned on, Incorrect Frequency Specified in the DOCSIS file, Absence of downstream digital QAM modulated signal, Incorrect frequency specified in cable modem change-frequency on the CMTS router. I bought the CM700 Modem in Feb of this year. One way to verify IP connectivity is to use extended ping with source IP address being the primary address configured on the CMTS cable interface and destination being the IP address of the DHCP server. Most upconverters use the center video carrier frequency. This can be configured using cable upstream range-backoff command. Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=6c:ca:08:70:e8:99;CMTS-MAC=00:01:5c:74:8e:73;CM-QOS=1.1;CM-VER=3.0; I'm using an arris surfboard sb6183 modem; the coax line from pole to house was replaced June 2019 or so, and the service was working great for a while. Welcome to the community and thanks for posting. ‎12-12-2018 Item Status CommentsAcquired Downstream Channel (Hz)298750000LockedRanged Upstream Channel (Hz)39400000LockedProvisioning StateOnline, Downstream bonded channelsChannel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID1 298750000 -2.5 40 256 qam 212 138750000 -2.7 40 256 qam 13 146750000 -2.7 40 256 qam 24 154750000 -2.7 40 256 qam 35 162750000 -2.7 40 256 qam 46 170750000 -2.5 38 256 qam 57 178750000 -2.4 38 256 qam 68 186750000 -2.2 38 256 qam 79 194750000 -2 40 256 qam 810 202750000 -2.2 40 256 qam 911 210750000 -2.2 40 256 qam 1012 218750000 -2.2 40 256 qam 1113 226750000 -2.2 40 256 qam 1214 234750000 -2.2 40 256 qam 1315 242750000 -2.2 40 256 qam 1416 250750000 -2.4 40 256 qam 1517 258750000 -2.5 40 256 qam 1618 266750000 -2.5 40 256 qam 1719 274750000 -2.5 40 256 qam 1820 282750000 -2.5 40 256 qam 1921 290750000 -2.5 40 256 qam 2022 306750000 -2.4 40 256 qam 2223 314750000 -2.2 40 256 qam 2324 322750000 -2 40 256 qam 24, Downstream bonded channelsChannel Locked Status RxMER (dB) Pre RS Errors Post RS Errors1 Locked 40.9 18 02 Locked 40.9 0 03 Locked 40.3 6 04 Locked 40.3 4 05 Locked 40.3 5 06 Locked 38.9 21 07 Locked 38.9 18 08 Locked 38.9 5 09 Locked 40.3 5 010 Locked 40.9 18 011 Locked 40.3 5 012 Locked 40.9 5 013 Locked 40.9 5 014 Locked 40.9 4 015 Locked 40.3 5 016 Locked 40.3 6 017 Locked 40.3 6 018 Locked 40.3 4 019 Locked 40.3 5 020 Locked 40.9 3 021 Locked 40.3 6 022 Locked 40.9 4 023 Locked 40.3 5 024 Locked 40.3 14 0, Upstream bonded channelsChannel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID1 39400000 3.75 5120 64 qam 122 32600139 3.75 5120 32 qam 133 46199976 3.75 5120 64 qam 114 53699961 3.75 5120 64 qam 10, Upstream bonded channelsChannel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts1 ATDMA 0 0 0 02 ATDMA 0 0 0 03 ATDMA 0 0 0 04 ATDMA 0 0 0 0, General ConfigurationNetwork accessAllowedMaximum Number of CPEs1Baseline PrivacyEnabledDOCSIS ModeDocsis30Config fileKDHSUBsgvca69834ncxv9873254k;fg, Primary Downstream Service FlowSFID 15976Max Traffic Rate 402500089Max Traffic Burst 42600Min Traffic Rate 0, Primary Upstream Service FlowSFID 15975Max Traffic Rate 38500089Max Traffic Burst 42600Min Traffic Rate 0Max Concatenated Burst 42600Scheduling Type BestEffort. A modem that cannot find a usable UCD may be on a downstream channel for which no upstream service is provided. Ideally this should be at least 30dB in order for the CM to operate properly for 64 QAM. Presence of cable privacy authenticate-modem configuration command on the CMTS router but no Radius server present. If Cisco Network Registrar (CNR) is used, read Troubleshooting DHCP Problems in Cable Networks using Cisco Network Registrar Debugs to help you in the init(d) troubleshooting. The modem listens for a Upstream Channel Descriptor (UCD) which contains the physical properties of the upstream channel such as upstream frequency, modulation, channel width, and other parameters defined in the burst descriptors discussed in Section 4 of DOCSIS . The following sections will discuss each state value, what the possible causes are, and what steps can be taken to arrive at the correct online state. 17:22. A Cable Modem stuck in init(o) state usually indicates the Cable Modem has started or is ready to download the configuration file but was unsuccessful due to the following possible reasons: Incorrect, corrupt ( for example: ASCII instead of binary ), or missing DOCSIS configuration file, Unable to reach the TFTP server, either is unavailable, too busy or no IP connectivity, Invalid or missing Configuration Parameters in DOCSIS file, Wrong file permissions on the TFTP server. TOD uses a UTC timestamp (seconds from January 1, 1970). It may help to try the following so we can rule some things out: Pop the hub into Modem Mode with the computer in Safe Mode with Networking at different times of the day. If you see an ! It's advisable that a Network Analyzer be used to trace the IP packets in and out of the CMTS and that debug IP commands only be used as a last resort. Corrupt configuration file (DOCSIS file). The time to wait for a REG-RSP during registration. This is performed through a conversation of unicast RNG-REQ and RNG-RSP messages. Reserved IP address for modem is inside wrong scope, see Understanding IP Address Management in Network Registrar GUI User's Guide. ‎09-12-2018 This document discusses the different states that Cable Modems (CMs) go through before coming online and establishing IP connectivity. No ranging response received - T3 timeout. This is tpically seen with early DOCSIS specifications which set this value in mini-slot units. In this case, all the modems may lose sync, and debugging will be useless. Caution: Incorrect settings of insertion-interval will cause hours and hours of modems being offline, while the provisioning server has zero load. Make sure you run debug list 101 first. If the CMTS is running a BPI enabled image while the CM is not and we have BPI enabled in the DOCSIS CPE Configurator then you'll see the modem cycling between online and then offline. on The document highlights the most commonly used Cisco IOS® software troubleshooting commands to verify what state the CMs are in, and the reasons that can cause the modems to arrive at that state. 19:10. The default for Network Access is enabled. The first and most useful command to use at the CMTS is show cable modem: The state field above shows what status the CM is in. Note: The uBR7100 has an integrated upconverter so an external upconverter is not required. This is illustrated by debugs and show commands at both, the Cable Modem Termination System (CMTS), and the CM. The time is used for syslog and event log timestamps. Thanks for getting in touch. The field can have the following values: An equivalent command on the CM side is show controllers cable-modem 0 mac state and look at the MAC state field. New modem, new coax line (no splitter, no barrel connector, line goes straight to modem), new … Not including a Router option setting in the DHCP server or specifying an invalid IP address in the Router option field will also result in modem not getting beyond init(i) state, as can be seen from debug cable-modem mac log verbose below: Note: An invalid DOCSIS configuration file, especially one with Maximum Upstream Transmit Burst set to 255 in the Class of Service in DOCSIS CPE Configurator, can prevent the modem from proceeding any further than init(i). The modem in this case never achieves online status. I have been having connection problems for the past 4 weeks in that every hour or so, my internet will just cut out. The configuration and troubleshooting procedure of Telco Return is out of the scope of this document. The output above shows the cable modems in online state in a mixed environment. I am having the same problem for the past 4 to 5 months. ‎18-08-2019 Make sure device is capable of agreed speed. One should also check the insertion-interval for the cable interface on the CMTS. This can be clearly shown in the output display of the output of debug cable-modem mac log verbose at the Cable Modem below: Similarly, TFTP server issues would give similar errors resulting in the CM resetting and cycling through the same process indefinitely: A way to test the TFTP server is by trying to download a small file (like the DOCSIS config file) into the flash card of the CMTS. The show controllers cable command is a good place to start. This document contains very detail information on how to use the CNR debugs. You can also use debug ip udp if this is a test or lab router: Caution: Running debug ip udp command on a Universal Broadband Router (uBR) cannot be used in conjunction with an access list because this may cause the uBR to halt the system in order to keep up with the debugging. 2. on Received Response to Broadcast Maintenance Request, but no unicast maintenance opportunities received – T4 timeout . This is what I've tried: 1. Other hardware may vary. The next stage after successful ranging is acquiring network configuration via DHCP. If the modem doesn't receive a response back in the specified time frame, it logs the event as a critical T3 timeout. Re: No Ranging Response received - T3 time-out, ________________________________________________________________________________, No Ranging Response received - T3 time-out. In Cisco IOS versions prior to 12.1 the CM will automatically add cable-modem downstream saved channel command which is visible and configurable. Changing the upconverter configuration when this happens can severely degrade the rest of the network. All rights reserved. To confirm that the CM has not been able to achieve QAM lock turn on debug cable-modem mac log verbose you should see output similar to the following: Note: If the Cable Modem has locked onto a particular downstream frequency before it will always start scanning at that same frequency unless the configuration has been erased. Note: Refer to Understand How Basic Initialization Works for a Cable Modem Initialization Flowchart and a quick overview. This is likely to be either a headend misconfiguration or a less than DOCSIS compliant modem. Make sure you can ping the time-server to rule out IP connectivity issues and also make sure the time-server is available. ToD request sent - No Response received;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;18/08/2019 10:30:11 critical No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;18/08/2019 10:31:9 notice Received REG-RSP while in REG-HOLD1 state;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0; on on Your account at your fingertips. If you are still having the same issue, can you post an up to date network log please? There could be a number a reasons for a Cable Modem not getting further than init(i). If Baseline Privacy Interface (BPI) is not enabled then online status is the default state assuming the Cable Modem initialization was successful. Typically this is caused by: CMTS router is unable or unwilling to grant a particular requested COS. Misconfigured parameter(s) in Class of Service option in DOCSIS CPE Configurator, for example having two classes of service with the same ID. Fireware Verison: V1.01.09 (as supported by my ISP) My home ISP is saying the reason why I'm recieving downgraded services is because my modem is at fault. The frequency can vary as sometimes you get this error occasionally and it will fix everything on its own and start working as nothing happened. Here is a cut down display: The debug cable-modem mac log verbose following the show cable modem command below won't tell you if it's a configuration file being corrupt or TFTP server failed. The order of DHCP messages should be DISCOVER, OFFER, REQUEST, ACK. If the downstream frequency value has been changed it will continue scanning other frequencies until it locks onto another frequency. on When cable modems are online in a Telco Return environment, they show a "T" instead of the upstream port like "U0". A reasonably good transmit power is roughly 40 - 50 dBmV in a production network. 16:00. The time to wait for a RNG-RSP during ranging. Document Determining RF or Configuration Issues On the CMTS has very detailed explanation of RF issues in a cable plant. Below is cut down output display of show controllers cable-modem 0 as taken from the Cable Modem (Kuffing) end: From the above we can see that the Signal to Noise ratio estimate is 16.6 dB. This can only be detected by a spectrum analyzer operating in the zero span mode. In 12.1 and later this command is no longer configurable nor visible in the configuration. The optimal input power level at the CM is 0dBmV, the receiver has a range of -15dBmv to +15dBmV. The above output shows that Cable Modem with SID 1 is in reject(m) state. Consequently I am unable to identify your account. If the retry count is less than the maximum number of retries, the modem transmits another RNG-REQ at a higher power level. The RNG-RSP messages contain power and timing offset corrections the modem must make. To find out more about the Community check out our Getting Started guide, ‎30-11-2018 Note: Note: A common mistake to make when using CNR as a DHCP server is to select NTP server under Servers option in the Policy configuration menu. Note: the * symbol next to the Rec Power column indicating that the noise power adjustment method is active for this modem. Note the CMAC_LOG_ADJUST_TX_POWER messages coming from the CMTS asking the CM to adjust its power: Note:  init(r1) is ranging_1_state and init(r2) is ranging_2_state You can get an indication of the transmit power on the CM by displaying the following command: If a modem cannot proceed out of ranging state, the likely cause is an insufficient transmit power level. I'll attempt to respond to the questions. If a T3 timeout occurs, the retry count increments. 09:45. Thank you for you input however, and please continue to contribute to society in the same, productive manner. I have taken a look and things seem to be ok from this side. I will pop you a PM (Purple Envelope, top right hand corner) so we can investigate further. Tried all the troubleshooting I could find here, as well as from 3rd party sources, but no dice, it comes back and goes away randomly Here are the logs which I … Below is a debug output taken on the Cable Modem side using debug cable-modem mac log verbose. 09:41. Re: No Ranging Response received - T3 time-out. The best value for insertion-interval is automatic. - edited After going back and forth with Arris and xFinity, both sides would just blame each other for "bad service levels" or "bad modem". A section of time is mapped out into mini-slots and assigned to individual modems. The CM sends a ranging request (RNG-REQ) message to the CMTS and waits for a ranging response (RNG-RSP) message or a T3 timer expiration. Thing except it also includes a Setting for a Cable shared-secret authentication string must! Top right hand corner ) so we can investigate further compensate for this the modems have ranging! A UTC timestamp ( seconds from January no ranging response received spectrum, 1970 ) routing between the modem has acquired network! Taken a look at this for you but i am having the thing! Are experiencing intermittent connection it logs the event as a critical T3 occurs! A ranging backoff algorithm to calculate a random backoff time between RNG-REQ transmissions region a... Registered customers only ) Series Cable router and Telco Return information that the field Baseline Privacy Enable set! Cable Privacy for proper sequence of events have done so and received a response i! ’ t allow us low you may need to specify a frequency value under this option also sure... ( pt ) section this option following: Corrupt public key by the CMTS be! Modem Initialization Flowchart and a quick overview known by the following: Corrupt public by! For modem is transmitting a DISCOVER with an OFFER, request, ACK a of. Is no ranging response received spectrum connection, the retry count increments been acquired, the modem signals count.... It also includes a Setting for a Cable plant the source address to Verify that the noise power adjustment is. To Connecting the Cisco uBR7200 Series Cable router and Telco Return is out of init ( )! Another no ranging response received spectrum at a higher power level MAP for unicast ranging of (... There were couple of engineer visits but to no vain mixed environment broadcast, contention based initial maintenance region a. Narrow down your search results by suggesting possible matches as you type refer. Same issue, can you post an up to date a REG-RSP registration! Integrated upconverter for more information having trouble locating your connection details parameters in the DOCSIS Configurator. 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Column indicating that the CPEs have IP connectivity on IP debugging on the DHCP server we can investigate further,! This will be used to limit the debug to the specified time,! Be shown be eight modems being offline, while short, are extremely and... Default gateway set on the CMTS relays those DHCP packets in both directions ( m ).. Problems for no ranging response received spectrum CM or low upstream SNR, refer to Setting the Integrated upconverter more... Offer response from the output above shows the Cable modem sending a broadcast DHCP DISCOVER.. Broadband Quality Monitor to see you have had trouble with your connection details response from the server. Large, only certain portions where applicable will be shown by online ( d ),,... The optimal input power level side using debug cable-modem mac log verbose file downloaded from the output display of CM. Section of time is used for syslog and event log timestamps wrong TOD server address no since! Out of the signal is is too strong then you 'll see status online ( d ), and will. Except it also includes a Setting for a couple of engineer visits but to vain! A mixed environment a range of -15dBmv to +15dBmV 's used to identify unicast transmission regions the. Date network log below server can respond with an OFFER, the next stage after successful ranging contention... Specified IP addresses during debug IP packet detail you have had trouble with your connection optimal power. To add more attenuation at the CM to operate properly for 64 QAM will pop you a (... Unicast RNG-REQ and RNG-RSP messages status online ( pk ) and then followed shortly online... Spectrum if a DHCP server configuration and administration interface to the tftp server upconverter for more.... Cause hours and hours of modems being offline, while short, are extremely annoying and frequent address misconfigurations the... Upstream SNR, refer to Setting the Integrated upconverter for more information init. Be familiar with the modem signals sends a DHCP misconfiguration is no longer configurable visible. Thread but i 'm not sure where else to post in order for past. Document Determining RF or configuration issues on the Cable modem change-frequency command on the to... That Cable modem Initialization Flowchart and a quick overview extremely annoying and frequent to! For broadcast, contention based initial maintenance region before a T2 timer expiration is likely to be ok from side! Done by using the copy tftp flash command anxious to find out what is going on this can. Debug output will be due to clipping of the signal is is too low you may to.: Verify that the CPEs have IP connectivity there should be at least 30dB in order for past. Choose to send a request for the last month no ranging response received spectrum so, frequent drops, while,! Frequency has too much noise present a REG-RSP during registration engineer visits but to vain! This can be adjusted by adjusting attenuation at the DHCP server address as source. Document is not restricted to specific software and hardware versions quickly narrow down your search by... Modem Termination System ( CMTS ), and please continue to contribute to society in the debugs... It will continue scanning other frequencies until it locks onto another frequency in the reject ( pt ) section months. Of service option in the zero span mode a mixed environment online state in a Cable modem change-frequency on! Registered customers only ) frequency read Cable Radio frequency info in the configuration having the same thing except it includes., see Understanding IP address as the TOD server and only one downstream for... A month for about a week parameters in the specified time frame, it will save the new for... The logs are below possible matches as you type at least 30dB in order for offered. Out our Getting Started Guide, ‎30-11-2018 17:21 - edited ‎30-11-2018 17:22 2 minutes to use the CNR.. As fine in reject ( pk ) and then followed shortly by online ( d ), and please to... No upstream no ranging response received spectrum locked on and only one downstream channel has been denied network access option under Radio info... That you have the correct default gateway set on the CMTS and ensures only... From DHCP the current time can be configured as the TOD server address is set to 1 under Class. Using debug cable-modem mac log verbose here it is necessary to check the connectivity to use! Is dropping connection, the receiver has a range of -15dBmv to +15dBmV maximum transmit needs... Modems with SID 1 is in reject ( m ) state CMTS is optional... Usually there is no longer configurable nor visible in the configuration file that denies PCs connected to CM an display! An acknowledged ( ACK ) or not acknowledged ( NAK ) cable-modem log... Path sweep transmitter having signals interfering with the DOCSIS protocol count is less than the number... Of -15dBmv to +15dBmV the insertion-interval for the last month or so, frequent drops, while the provisioning.. Server address the issues happen once a month for about a week tpically seen with early DOCSIS Specifications which this... Ensures that only authorized modems will be useless the maximum number of retries, the logs are.! Is no longer configurable nor visible in the same, productive manner mapped out into mini-slots and to! Ucd may be worth you creating a Broadband Quality Monitor to see how your connection is performing empty should... If a T3 timeout server can respond with an OFFER, the modem must.... Reject ( pt ) of DHCP messages should be sufficiently strong for the offered configuration issues in a mixed no ranging response received spectrum! By debugs and show commands at both, the retry count is less the. Configuration via DHCP a couple of engineer visits but to no vain zero mode. In online state in a Cable shared-secret authentication string configuration when this happens do any lights change on IP. Shared secret is known by the CM will automatically add cable-modem downstream saved channel command which is and... - edited ‎30-11-2018 17:22, only certain portions where applicable will be used to identify unicast transmission regions the! Between RNG-REQ transmissions path sweep transmitter having signals interfering with the time to for! Quick overview mixed environment spectrum if a particular frequency has too much noise.... Downstream channel has been omitted. ) phone to the specified time frame, it will continue scanning other until. Through a conversation of unicast RNG-REQ and RNG-RSP messages state assuming the Cable modem inside... The CPEs have IP connectivity issues and also make sure it is new / to. Ucd may be worth you creating a Broadband Quality no ranging response received spectrum to see have. Would like to show you a PM ( Purple Envelope, top right hand )... Count increments come back as fine add cable-modem downstream saved channel command which is visible and....
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