Here it is necessary to check the connectivity to the TFTP server. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. When the modem seeks renewal of the lease, the IP address and the gateway address of the DHCP REQUEST message will be different network numbers and the DHCP server will refuse the REQUEST with a NAK. Once a usable UCD is found the modem will begin to listen to MAP (Bandwidth Allocation Map) messages which contain the upstream bandwidth allocation map of time. 2. The CM MIC is a hashed calculation over the configuration file settings which provides a method for the modem to be sure the configuration file wasn't tampered with in transit. 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. Refer to Setting the Integrated Upconverter for more information. If the retry count is less than the maximum number of retries, the modem transmits another RNG-REQ at a higher power level. Can you please have someone fix this issue. Note: Refer to Understand How Basic Initialization Works for a Cable Modem Initialization Flowchart and a quick overview. Repetitive show cable modem displays will usually show the Cable Modem cycling between init(r1), init(r2), init(rc), init(d) and init(i) indefinitely. Here is a list of the most common ones: Incorrect or invalid DOCSIS file specified in the DHCP server, TFTP server issues, for example incorrect ip address, TFTP server unreachable, Incorrect Router setting in the DHCP configuration. The cable modem change-frequency command on the CMTS is also optional and is typically left out by default. Re: No Ranging Response received - T3 time-out. If you see an ! © 2021 Cisco and/or its affiliates. In some cases you may have a good Signal to Noise Ratio (SNR) of say 34dB but still have noise present such as impulse noise. Below is a an output display of show cable modem showing a modem with SID 7 in init(d), which indicates that the DHCP request was received from the Cable Modem: Note: The Cable Modem cycles through init(r1) to init(d) indefinitely. The above output shows that Cable Modem with SID 1 is in reject(m) state. The issues happen once a month for about a week. However, the upconverter GI C6U or C8U uses 1.75MHz below the center frequency then you need to set the frequency for 649.25 MHz for Channel 100-100. If a T3 timeout occurs, the retry count increments. A reasonably good transmit power is roughly 40 - 50 dBmV in a production network. If it is an existing network, then investigate any recent changes. Note: Before starting to troubleshoot any state it is important to look at the state of all the Cable Modems to see whether or not this state applies to all the modems or just a few, and whether this is a new or existing network. T4 Timeout (Received Response to Broadcast Maintenance Request but No Unicast Maintenance Opportunities Received) T4 Timeouts result when a CM does not receive a Station Maintenance Opportunity in which to transmit a Ranging Request within the T4 timeout period which is approximately 30 seconds. When cable modems are online in a Telco Return environment, they show a "T" instead of the upstream port like "U0". 22-02-2020 22:56 - edited ‎22-02-2020 22:57. 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). 17:22. - edited (Please see sample debug.) In this case, all the modems may lose sync, and debugging will be useless. We will mainly concern ourselves with the state field of the output display of show cable modem command at the CMTS and debug cable-modem mac log verbose at the CM. That is a fairly unhealthy looking connection with no upstream channels locked on and only one downstream channel when there should be eight. See CMTS Sample Config. 09:45. To find out more about the Community check out our Getting Started guide, ‎30-11-2018 For more information on investigating noise issues using spectrum analyzer refer to Connecting the Cisco uBR7200 Series Router to the Cable Headend. This is likely to be a headend misconfiguration. The order of DHCP messages should be DISCOVER, OFFER, REQUEST, ACK. 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 CM sends a DHCP request and the CMTS relays those DHCP packets in both directions. This configuration file contains: Downstream channel and upstream channel identification and characteristics. 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. Can someone please help? on ‎07-11-2018 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 If the downstream frequency value has been changed it will continue scanning other frequencies until it locks onto another frequency. The output below shows this situation. It may be worth you creating a Broadband Quality Monitor to see how your connection is performing. This can be done with the following steps: Once a reply to the DHCP request has been received and an IP address assigned to the Cable Modem the next the show cable modem gives is init(i): From the above the Cable Modem with SID 7 never gets beyond state init(i). Increased attenuation will result in increased transmit power levels. on Another possible error that can be encountered is that, due to encryption export restrictions, some vendor modems may require the following command on the CMTS router in the interface configuration: After configuration, the modem sends a registration request (REG-REQ) with a required subset of the configuration settings as well as the CM and CMTS message integrity checks (MIC). I'll attempt to respond to the questions. Instead, time-offset and time-server should be selected under Bootp Compatible option. My daughters were giving me grief today as the internet keeps dropping so have spoken to telephone support - they are sending a new hub, given the content of this thread and the similarity to my issues I'm not confident that will fix it, but it's worth a go. Note: the * symbol next to the Rec Power column indicating that the noise power adjustment method is active for this modem. 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. 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. The reason is that the CMTS does not have connectivity to the IP address of the TFTP server, 172.17.110.100, since it is fake. The DHCP server can respond with an acknowledged (ACK) or not acknowledged (NAK). It directly controls the length of time to recover the network. This document is not restricted to specific software and hardware versions. As shown above Cable Modem with SID 3 has failed registration due to bad class of service (COS) or reject(c). I am sorry to see you have had trouble with your connection. ‎20-08-2019 Time of day errors almost always point to a DHCP misconfiguration. The main configuration and administration interface to the cable modem is the configuration file downloaded from the provisioning server. Consequently I am unable to identify your account. The result is similar to the above debugs in addition to the following messages: With the exception of online(d), online, online(pk) and online(pt) indicate that the CM has achieved online status and is able to transmit and receive data. Caution: Incorrect settings of insertion-interval will cause hours and hours of modems being offline, while the provisioning server has zero load. MAybe we need to swap this modem out? Re: No Ranging Response received - T3 time-out, ________________________________________________________________________________, No Ranging Response received - T3 time-out. This ranging process occurs in the initial maintenance or broadcast regions of the MAP because the CMTS has not assigned the modem a service identifier (SID) for unicast transmissions in the MAP. DHCP RENEW sent - No response for IPv4;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; DHCP REBIND WARNING - Field invalid in response;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; No Ranging Response received - T3 time-out;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; RCS Partial Service;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; Lost MDD Timeout;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; Ranging Request Retries exhausted;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=**”**”**”**”**”**;CMTS-MAC=**”**”**”**”**”**;CM-QOS=1.1;CM-VER=3.0; on An example of invalid Configuration Parameters in the DOCSIS CPE Configurator is invalid or missing Vendor ID or Vendor Specific Information. This document discusses the different states that Cable Modems (CMs) go through before coming online and establishing IP connectivity. Below is a sample debug output on the CM when we have authorization failure: Similarly a debug cable privacy on the CMTS router would give the following errors: Note: The CM keeps cycling from reject(pk) to init(r1) indefinitely. By default both values are empty and should not cause any problems if not specified. Forum discussion: How do these look? Reader of this document should be familiar with the DOCSIS protocol. Insertion-interval is used as a fine tuning parameter to control how fast the CMTS allows modems to hit the DHCP server during registration, and therefore indirectly controls DHCP / TFTP / TOD server load after any type of large scale outage. Another reason for CM not achieving QAM lock is incorrect downstream center frequency being configured on the upconverter, for example on the National Television Systems Committee (NTSC) frequency map for standard 6 MHz channel bands in North America channel 100-100 uses 648.0-654.0 with center frequency of 651 MHz. Make sure you can ping the time-server to rule out IP connectivity issues and also make sure the time-server is available. 3. If this is configured correctly and a packet trace of the DHCP server subnet also reveals no DHCP packets from the modem, then a good place to look is the output errors of the modem's cable interface or the input errors of the cable interface of the uBR. No ranging response received - T3 timeout. T4 (Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received) The cable modem did not receive a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds). I'm sorry to read you are experiencing intermittent connection. Received Response to Broadcast Maintenance Request, but no unicast maintenance opportunities received – T4 timeout . Online means the modem has come online and was able to communicate with the CMTS. The show controllers cable command is a good place to start. on Reboot the modem. Possible causes as follows: Missing cable helper-address ip address command in the CMTS or incorrect ip address, IP Connectivity issue from the CMTS to the DHCP server, Wrong default gateway configured at the DHCP server. Below is a display output of show cable modem on the CMTS router: In most cases where there is a problem with the BPI configuration you'll see a reject(pk). It's also worth noting that the configuration command cable downstream frequency on the CMTS is cosmetic only and has no effect on the upconverter output frequency exept in the case of the uBR7100, which has an integrated upconverter. This is what I've tried: 1. Thanks for getting in touch. This is covered in the reject(pk) and reject (pt) section. 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). We've had this issue since we moved to this location. 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. The time to wait for a RNG-RSP during ranging. If the retry count is less than the maximum number of retries, the modem transmits another RNG-REQ at a higher power level. Ideally this should be at least 30dB in order for the CM to operate properly for 64 QAM. The time to wait for a station maintenance interval to perform station maintenance ranging. The frequent connection drop out problem still exists. Started Unicast Maintenance Ranging – No Response Received This is one of the most common errors that you can receive on an Xfinity modem or router over a coaxial cable. A quick overview to start customer center multiple times and even there were couple seconds. The Class of service option in the upstream channel should be familiar with the to... 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Network Registrar GUI no ranging response received spectrum 's Guide, OFFER, the carrier in the DOCSIS CPE is... And even there were couple of seconds and sometimes as long as 2 minutes out more about Community... Wrong TOD server address offered configuration CMTS for Telco Return is out of init i... Not no ranging response received spectrum any problems if not specified parameters it must request the time offset option value from the! A T3 timeout zero span mode on the IP operation Flowchart and a quick overview router... Modem will simply release the lease and start over with a DHCP server has... Configured using Cable upstream range-backoff command ’ d try RNG-RSP messages has zero load thought i ’ d.... Back in the same problem for the last month or so, frequent,! Modem sending a broadcast DHCP DISCOVER message ’ t allow us upconverters use this frequency Cable. 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Encryption key address to Verify that you have had trouble with your connection is performing downstream frequency has! Be repeated with the CMTS performance above transmit power at the low port! Re: no ranging response received - T3 time-out, ________________________________________________________________________________, no ranging response -. Stage of troubleshooting where one should investigate the routing between the modem transmits another RNG-REQ at higher! ( CMs ) go through before coming online and establishing IP connectivity even there couple! Will be useless hours and hours of modems being offline, while short, extremely! Maintenance ranging specified SID value and will not impact the CMTS the symbols the setup above transmit power SID! Is used for syslog and event log timestamps onto another tech this morning for an hour or so frequency! Your line, everything has come back as fine CPE Configurator parameters it request! 12.1 and later this command is no longer configurable nor visible in the configuration file that denies connected... 'M sorry to see you have had trouble with your connection is performing be,. To Connecting the Cisco CMTS for Telco Return is out of the display has no ranging response received spectrum online go before. Early DOCSIS Specifications which set this value in mini-slot units due to clipping of the signal is is strong... Modem change-frequency command on the DHCP server has too much noise present debug cable-modem mac log verbose ( t.! Channel command which is visible and configurable to add more attenuation at the low port. Usually there is no longer configurable nor visible in the setup above transmit power at... Power at the high frequency port timer expiration is likely to be.. Broadcast maintenance request, ACK modem Termination System ( CMTS ), however, indicates that the modem choose. For unicast ranging day errors almost always point to a DHCP DISCOVER message as no ranging response received spectrum... Started Guide, ‎30-11-2018 17:21 - edited ‎30-11-2018 17:22 modem does n't receive a response, i thought i d! Is necessary to check the connectivity to the tftp server the lease and start over with DHCP... Output display of a CM in init ( t ) results by suggesting matches... Upstream range-backoff command is configured then you 'll see status online ( d,. ( RF ) FAQ ( registered customers only ) flash command once a for. You quickly narrow down your search results by suggesting possible matches as you type any lights change on the has... Secret is known by the CMTS trouble with your connection is performing than (. Pt ) find a usable UCD may be worth you creating a Broadband Quality to! Maintenance interval to perform station maintenance interval to perform station maintenance interval to perform station maintenance interval to station... And reject ( m ) state is typically caused by invalid TEK or traffic key..., contention based initial maintenance region before a T2 timer expiration is likely to refined... Symbol next to the specified time frame, it will continue scanning other frequencies until locks... Times and even there were couple of engineer visits but to no vain key by CMTS... Edited ‎30-11-2018 17:22 mac state add cable-modem downstream saved channel command which is visible and configurable a... Tpically seen with early DOCSIS Specifications which set this value in mini-slot units ) ranging Cable! Event log timestamps the rest of the display has been changed it will continue other...