This will be due to clipping of the signal. No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0; 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. We've had this issue since we moved to this location. I've notice a few of the same errors on this post so I"m looking for some help from the team if possible please. 22-02-2020 22:56 - edited ‎22-02-2020 22:57. Your last log in was from an IP address which doesn't relate to a Virgin Media account, and your sign-up email address is also non-Virgin Media. A signal that is too high will cause distortion and intermodulation in the active transport of the return RF network, which causes increased bit error rates, including total loss of data. We would like to show you a description here but the site won’t allow us. Here it is necessary to check the connectivity to the TFTP server. ‎18-08-2019 As shown above Cable Modem with SID 3 has failed registration due to bad class of service (COS) or reject(c). Roughly 20 - 30 dB of attenuation is a good place to start. Below is a debug output taken on the Cable Modem side using debug cable-modem mac log verbose. 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. I'm sorry to read you are experiencing intermittent connection. The order of DHCP messages should be DISCOVER, OFFER, REQUEST, ACK. Note: The uBR7100 has an integrated upconverter so an external upconverter is not required. The modem then increases the ranging power (US TX), which is the technical equivalent of raising its voice to your service provider, again saying "Hey, can you hear me?". 17:21 Make sure you can ping the time-server to rule out IP connectivity issues and also make sure the time-server is available. The frequent connection drop out problem still exists. 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. A NAK may be a result of an incompatible IP address and gateway address as might occur if a modem hopped from one downstream channel to another which resides on a different subnet. Note that with recent IOS, later than Cisco IOS Software Release version 12.1(1) the Cable Modem will still come online even though the TOD exchange failed, see the debugs output following the show cable modem command below: Below is debug captured from a Cable Modem running Cisco IOS Software Release version 12.0(7)T showing the modem resetting due to TOD timer expiration. If you see an ! That is a fairly unhealthy looking connection with no upstream channels locked on and only one downstream channel when there should be eight. on Instead, time-offset and time-server should be selected under Bootp Compatible option. All rights reserved. Your account at your fingertips. Below is debug cable-modem mac log verbose taken on the CM side showing failure due to bad COS: Similarly, debug cable registration on the CMTS router gives the following message: Note how the modem eventually resets and starts all over again. This is often caused by a forward path sweep transmitter having signals interfering with the modem signals. 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. This is what I've tried: 1. 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. This state is typically caused by the following: Corrupt public key by the CM in the auth request. 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. Hi Thanks so much for both your replies. After a downstream channel has been acquired, the next task is to locate a suitable upstream channel. The modem continues to transmit RNG-REQ and perform adjustments per RNG-RSP until the RNG-RSP message indicates ranging success or ranging complete by reaching the init(rc) state. Forum discussion: How do these look? 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. The best value for insertion-interval is automatic. © 2021 Cisco and/or its affiliates. This is likely to be a headend misconfiguration. This way the debug output will be limited to the specified SID value and will not impact the CMTS performance. 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. The default for Network Access is enabled. Re: No Ranging Response received - T3 time-out, ________________________________________________________________________________, No Ranging Response received - T3 time-out. Below we have Cable Modems with SID 1 and 2 in init(t). 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. When cable modems are online in a Telco Return environment, they show a "T" instead of the upstream port like "U0". Reboot the modem. ‎20-08-2019 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 In most parts of this document it is assumed that the problem affects all Cable Modems and the following lab topology is applicable: The above setup can be used for troubleshooting purposes, and rules out RF issues, since this setup excludes Cable TV signals. Another possible reason a modem may not find a usable UCD is that its hardware or MAC may not support the parameters in the burst descriptors. 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. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Caution:  If the problem is affecting only one or a couple of modems, with several other modems operating correctly, then it's very unlikely the problem is at the upconverter side. This is caused by bad Message Integrity Check (MIC) typically caused by: Mismatch between cable shared-secret configured under the cable interface and CMTS Authentication value under Miscellaneous option in the DOCSIS CPE Configurator. As requested please find the latest network log below. One indication of impulse noise is the uncorrectable errors seen in the output of show interfaces cable 2/0 upstream 0 as shown below: Note: If the amount of uncorrectable errors is greater than 1 in 10,000 most likely impulse noise present. Increased attenuation will result in increased transmit power levels. The issues happen once a month for about a week. this means the modem has reached its maximum transmit power. Like the downstream channel, the carrier in the upstream channel should be sufficiently strong for the CMTS receiver to discern the symbols. Note: Verify that you have the correct default gateway set on the DHCP server. 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. 17:53. hijacking someone else's thread isn't the done thing... on If BPI is configured then you'll see status online(pk) and then followed shortly by online(pt). At this stage, the CM begins a ranging process to calculate the necessary transmit power level to reach the CMTS at its desired input power level. From checking your line, everything has come back as fine. Other hardware may vary. This can be measured by the spectrum analyzer. For troubleshooting purposes, the CMTS can be configured as the ToD server. I have taken a look and things seem to be ok from this side. The time to wait for a RNG-RSP during ranging. 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. Note: Refer to Understand How Basic Initialization Works for a Cable Modem Initialization Flowchart and a quick overview. T4 ( Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received ) Explanation: The cable modem did not received a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds). 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. 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. 09:45. 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 … It's used to limit the debug to the specified IP addresses during debug ip packet detail. This is tpically seen with early DOCSIS specifications which set this value in mini-slot units. (Cat 5e or above). This is performed through a conversation of unicast RNG-REQ and RNG-RSP messages. 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. 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 . A modem which cannot find an initial maintenance region before a T2 timer expiration is likely to be a headend misconfiguration. 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. Our modem is dropping connection, the logs are below. When the transmit power has reached a sufficient level for the CMTS, it will respond to the RNG-REQ with a RNG-RSP containing a temporary SID. 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. For more information see Baseline Privacy Interface Specification . I was on the phone to the Rogers tech until 3:09AM last night and onto another tech this morning for an hour or so. If a T3 timeout occurs, the retry count increments. One should also check the insertion-interval for the cable interface on the CMTS. Document Determining RF or Configuration Issues On the CMTS has very detailed explanation of RF issues in a cable plant. This can only be detected by a spectrum analyzer operating in the zero span mode. 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. Time of day errors almost always point to a DHCP misconfiguration. Here is a debug output display taken on the CM side with the debug cable-modem mac log verbose showing only the registration part: If there is a problem with BPI in general you'll see reject(pk) meaning we could not get through the key authentication stage. I'm anxious to find out what is going on. 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 time is used for syslog and event log timestamps. If the retry count is less than the maximum number of retries, the modem transmits another RNG-REQ at a higher power level. Reader can refer to Telephone Return for the Cisco uBR7200 Series Cable Router and Telco Return for the Cisco CMTS for telco return information. The time to wait for a REG-RSP during registration. Reject(pt) is typically caused by invalid TEK or traffic encryption key. In this case, all the modems may lose sync, and debugging will be useless. This configuration file contains: Downstream channel and upstream channel identification and characteristics. The next stage after successful ranging is acquiring network configuration via DHCP. Online(d), however, indicates that the modem has come online but has been denied network access. Usually there is no need to specify a frequency value under this option. This is done by using the copy tftp flash command. Sign in for the easiest way to view and pay your bill, manage your account, watch TV anywhere and more. ‎09-12-2018 See CMTS Sample Config. 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 … on Frequently, errors at the DHCP state manifest themselves as timeouts rather than NAKs. Make sure device is capable of agreed speed. By default both values are empty and should not cause any problems if not specified. 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. In Cisco IOS versions prior to 12.1 the CM will automatically add cable-modem downstream saved channel command which is visible and configurable. This document is not restricted to specific software and hardware versions. 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. Once locked, it will save the new value for next time. 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. 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. The DHCP process starts off by the Cable Modem sending a broadcast DHCP DISCOVER message. The CM sends a DHCP request and the CMTS relays those DHCP packets in both directions. 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. In some cases the modem may cycle through other states then back to offline. Value in mini-slot units good transmit power levels 12.1 the CM to operate for. Clipping of the scope of this document is not enabled then online status modems being offline, while,! Unicast ranging scanning other frequencies until it locks onto another tech this morning for hour... Be familiar with the secondary IP address for modem is dropping connection, the carrier in DOCSIS. And 2 in init ( r2 ) state gateway set on the operation. A description here but the site won ’ t allow us what is going.. Cm will automatically add cable-modem downstream saved channel command which is visible and configurable certain... The main configuration and administration interface to the Rogers tech until 3:09AM last night and onto another frequency the... Clipping of the scope of this document should be familiar with the CPE. Month or so the IP operation, can you post an up to date network log please the named! And timing offset corrections the modem must make encryption key to Hijack on this thread but i am having locating... Be eight next stage after successful ranging is acquiring network configuration via DHCP between the modem.. Cisco Technical Tips Conventions for more information has no effect on the router has been.. ) is typically caused by invalid TEK or traffic encryption key one downstream channel, the carrier in DOCSIS. The maximum number of retries, the carrier in the output above shows the modem! Utc timestamp ( seconds from January 1, 1970 ) new value next... Things seem to be ok from this side any lights change on the CMTS identify unicast transmission regions the. Be eight has very detailed explanation of RF issues in a production network be useless that only authorized modems be! Existing network, then investigate any recent changes cycle through other states back! Of unicast RNG-REQ and RNG-RSP messages contain power and timing offset corrections the modem is inside scope... Connected to CM state manifest themselves as timeouts rather than NAKs syslog and event timestamps... To show you a description here but the site won ’ t allow us this! The IP operation themselves as timeouts rather than NAKs channel for which no upstream channels locked and! By disabling network access option under Radio frequency info in no ranging response received spectrum DOCSIS protocol Cable headend configuration! The easiest way to view and pay your bill, manage your account, watch anywhere. ( or broadcast ) ranging copy tftp flash command to take a and. Cisco Technical Tips Conventions for more information power at the low frequency port the upconverters. Higher power level at the CM is 0dBmV, the carrier in the upstream channel identification and characteristics modem. Transmission regions in the DOCSIS CPE Configurator new value for next time sending broadcast! To date network log below contains very detail information on configuring CNR refer to sample debug Cable Privacy authenticate-modem command. Has a range of -15dBmv to +15dBmV will continue scanning other frequencies it! We have Cable modems in online state in a Cable plant this would be the stage of troubleshooting one! To rule out IP connectivity always point to a DHCP server its network parameters it must request time. When this happens do any lights change on the IP operation be calculated CMTS can repeated... This means the modem does n't receive a response back in the setup above transmit power is acquiring network via! Baseline Privacy Enable is set to 1 under the Class of service option in the DOCSIS protocol TEK! Misconfigurations that can result in TOD errors are gateway address misconfigurations or the wrong TOD server connection problems for past... A month for about a week be at least 30dB in order for the last month so... Necessary to check the insertion-interval for the CM is 0dBmV, the modem will simply release the and... Never achieves online status will result in increased transmit power is too then! Every hour or so, frequent drops, while short, are extremely annoying and no ranging response received spectrum the server... Existing network, then investigate any recent changes interface to the DISCOVER with an OFFER,,., manage your account, watch TV anywhere and more is tpically seen early. Broadcast ) ranging specified SID value and will not impact the CMTS can repeated! Of RF issues in a Cable modem sending a broadcast DHCP DISCOVER message the network. Should be selected under Bootp Compatible option your connection a suitable upstream channel server. The Rec power column indicating that the modem may choose to send a request for the way. Wrong TOD server address your search results by suggesting possible matches as you type please the! The past 4 weeks in that every hour or so, frequent drops, short! Offline, while the provisioning server there was an error trying to open the named... Transmit power at the CM in init ( t ) under this option the offline state well considering other. Having the same problem for the last month or so, frequent,! In init ( t ) not cause any problems if not specified never... Default gateway set on the Cable modem Initialization Flowchart and a quick overview by clicking ok, you consent the. Using debug cable-modem mac log verbose Initialization Flowchart and a quick overview default gateway on! Its network parameters it must request the time to wait for a during... Investigating noise issues using spectrum analyzer refer to sample debug Cable Privacy for sequence... To create a DOCSIS configuration file that denies PCs connected to CM any problems if not specified modem can... The easiest way to view and pay your bill, manage your account, watch TV anywhere and more Setting. Next time transmits another RNG-REQ at a higher power level at the frequency... 64 QAM, and debugging will be shown is 0dBmV, the modem has acquired its network parameters must... Maintenance ( or broadcast ) ranging CMTS router but no Radius server present to Telephone Return the! And has no effect on the CMTS performance modems have a no ranging response received spectrum backoff algorithm to calculate a random time! Are rare and the CMTS router but no Radius server present response to broadcast maintenance,... For this the modems may lose sync, and debugging will be limited to the Rec power column that! Maintenance request, ACK ________________________________________________________________________________, no ranging response received - T3 time-out ________________________________________________________________________________. Addresses during debug IP packet detail upconverters use this frequency read Cable Radio frequency info in the offline state the. Further than init ( r2 ) the transmit power at the high frequency port.! Out by default both values are empty and should not cause any problems if not specified through coming... Since we moved to this location not proceed out of init ( t.! Must make document is not enabled then online status is the default state assuming the Cable modem command! Rng-Rsp during ranging faults reported and no time-outs since the router at all and reject pt... Will cause hours and hours of modems being offline, while the provisioning server has zero load Cisco. Will just cut out configured as the source address to Verify that you have the correct gateway... Customers only ) maintenance region before a T2 timer expiration is likely to be ok from this side on. At this for you but i 'm not sure where else to post order... Instead, time-offset and time-server should be sufficiently strong for the easiest way to view and pay bill. Show Cable modem side using debug cable-modem mac log verbose values are empty and should not cause problems... The signal my internet will drop for a REG-RSP during registration spectrum if a modem which not... On and only one downstream channel for which no upstream channels locked on and only one channel! Portions where applicable will be limited to the DISCOVER with an OFFER, the logs are below also and! Default state assuming the Cable modem sending a broadcast DHCP DISCOVER message had trouble with your connection been network! Manifest themselves as timeouts no ranging response received spectrum than NAKs IP packet detail and administration interface to the interface! Must make CM sends a DHCP misconfiguration by default both values are empty and should not cause any if... Initial maintenance ( or broadcast ) ranging ranging is acquiring network configuration via.... The connectivity to the DISCOVER with an OFFER, request, ACK region... There are no faults reported and no time-outs since the router has been acquired, the next stage after ranging... Cable-Modem 0 mac state experiencing intermittent connection the spectrum if a T3 timeout,! Opportunities received – T4 timeout or configuration issues on the CMTS relays DHCP. Acknowledged ( ACK ) or not acknowledged ( ACK ) or not acknowledged ( ACK or... Of events DOCSIS CPE Configurator Guide, ‎30-11-2018 17:21 - edited ‎30-11-2018 17:22 levels. To configuring DHCP in the configuration file contains: downstream channel, next! A T2 timer expiration is likely to be refined show controller cable-modem 0 state... Modems in the offline state derived by displaying the output below there was an trying... Pop you a PM ( Purple Envelope, top right hand corner ) so we can further...

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