BSR Troubleshooting Guide
Notice Copyright © 2001 Motorola, Inc. All rights reserved No part of this publication my be reproduced in any form or by any means or used to make and any derivative work (such as translation, transformation or adaptation) without written permission from Motorola, Inc. Motorola reserves the right to revise this publication and to make changes in content from time to time without obligation on the part of Motorola to provide notification of such revision or change.
Contents Preface Scope ix Audience ix Documentation Set ix BSR 1000™ Documentation Set ix BSR 1000™ Documentation Set x Conventions xi Notes, Cautions, Warnings Contacting Support 1 xii xiii Introduction Introduction 17 Understanding Basic Troubleshooting Discovering Problems Viewing Symptoms Isolating the Problem Solving the Problem Evaluating the Solution 2 17 18 19 19 20 20 Checking Physical Equipment Introduction 23 iii
BSR Troubleshooting Guide Checking BSR 1000 Power Connections 23 Checking BSR 64000 Power Connections 23 Checking Physical Network Connections Interpreting BSR 64000 LED Displays SRM LEDs 24 24 25 Module LEDs 25 Fan Status LEDs Alarm LEDs 26 27 DOCSIS CMTS Resource Module LEDs Module LEDs 28 Per-Port LEDs 28 28 OC3/OC12 POS Resource Module LEDs Module LEDs 29 Per-Port LEDs 30 Interpreting BSR 1000 LED Displays System LEDs 31 31 Upstream and Downstream Port LEDs Ethernet Port LEDs 3
Contents Bad Upstream Signal-to-noise Ratio Detected Upstream Power Level Too Low or High 58 61 Resolving Problems on the Downstream Path 63 Bad Downstream Signal-to-Noise Ratio Detected Downstream Power Level Too Low or High Resolving Cable Modem Problems 64 65 67 Misconfigured Authentication String or Key 67 CM Does Not Reply to Station Maintenance Requests CM is Offline 70 CM Cannot Obtain an IP Address 72 Provisioning Problems Cause CMs Not to Register CM Does Not Respond to SNMP Messages
BSR Troubleshooting Guide Misconfigured or Missing Network Router Table Entries Misconfigured Route Filtering Split Horizon is Disabled 99 100 101 Handling RIP Version Inconsistencies 101 Misconfigured Version of RIP Running on BSR 101 Misconfigured Version of RIP Running on Specified Interface 7 Troubleshooting OSPF Introduction 109 Handling OSPF-designated Interface Problems 109 Handling Router Neighbor Misconfigurations Misconfigured Router 110 110 Mismatched OSPF Parameters 111 Misma
Contents LOP Resolution 131 Failed POS Module 131 Fail LED Blinks and Lights Repeatedly Handling Data Loss on SONET Link Data Loss Determination Data Loss Resolution A 131 132 132 134 Cable Modem Registration Process Introduction 137 Scanning 137 Initial Ranging 138 Establishing IP Connectivity Establishing Time of Day TFTP Connectivity Registration 139 139 139 Baseline Privacy 140 Periodic Ranging 140 Data Exchange 138 141 Index vii
Preface Scope This document describes how to troubleshoot the Motorola™ Broadband Services Router™ 64000 (BSR 64000™) and Motorola™ Broadband Services Router™ 1000 (BSR 1000™), including hardware, applications, servers, databases, and routing and SONET-access features. This guide uses the term network to refer to subscriber cable modems, the BSR family of products, cables and equipment, and host servers.
BSR Troubleshooting Guide • BSR 1000 Configuration and Management Guide This document provides the instructions and procedures for configuring and managing the BSR 1000. • BSR 1000 Installation Guide This document describes how to install the BSR 1000 product. • BSR 1000 Release Notes These documents provide information about features not described or incorrectly documented in the main documentation set; known problems and anomalies; product limitations; and problem resolutions.
Preface • BSR 64000 SNMP MIB Reference Guide This document describes the Simple Network Management Protocol (SNMP) MIBs; provides information that describes standard and proprietary MIB support; describes how to walk the MIBs and how to compile and load the SNMP MIBs. It also provides task examples. Conventions This document uses the conventions in the following table: Convention Example Explanation angle brackets < > ping ping 54.89.145.
BSR Troubleshooting Guide Convention Example Explanation screen display Wed May 6 17:01:03 2000 This font indicates system output. vertical bar | page {on | off} A vertical bar separates the choices when a parameter is required. The example indicates you can enter either command: page on or page off When entering the parameter, do not type the vertical bar or the brace brackets. Notes, Cautions, Warnings The following icons and associated text may appear in this document.
Preface Contacting Support Use the following information to contact Support: U.S. 1-888-944-HELP 1-888-944-4357 International +.215-323-0044 WWW http://www.gi.com/BUSAREA/CUSACC/websupport.html Email cmtssupport@motorola.
1 Introduction
Introduction Introduction This chapter identifies the basic tasks you perform to solve problems with the network and hardware and software configurations.
BSR Troubleshooting Guide 4. Document the changes and effects of changes as you perform troubleshooting procedures, and note any new troubleshooting procedures that you use. This simple precaution helps to avoid repeating steps, allows for future reference in case the problem reoccurs, and is especially useful for troubleshooting intermittent problems. 5. Determine if the problem is solved. Ensure that the troubleshooting procedure did not cause new problems. 6.
Introduction • Record any changes that occurred since the last time the BSR was operating properly. Investigate any configuration changes that might be related to the problem. Viewing Symptoms Perform the following tasks to view and compare symptoms that are related to a problem: • Repeat the conditions that led to the symptom. Consider any errors or failures that can cause a particular symptom, and test them to see if they are causing the symptom. • Determine if any symptoms are related.
BSR Troubleshooting Guide Solving the Problem Different problems require different actions and solutions, but follow these basic steps to fix any problem: 1. Identify the course of action and the steps you plan to take. 2. Decide what tools are necessary to fix the problem on the network. For example, you can use the CLI as a tool to look at events and set SNMP traps. You can use a cable tester to check physical media connections. 3. Perform each step for the course of action. 4.
2 Checking Physical Equipment
Checking Physical Equipment Introduction This chapter discusses how to check physical connections and observe LEDs on the BSR products. You should check power and network connections anytime you install new hardware, or whenever a problem occurs.
BSR Troubleshooting Guide Checking Physical Network Connections Check network connections for loose, broken, or disconnected cables. Inspect the cable terminating connectors for damage. Use the following techniques to troubleshoot physical cables on the network: • • • Use the CLI show commands to view port and slot information. • Use cable testing equipment to measure or ensure that the correct distances for cable runs are in place.
Checking Physical Equipment 2. Observe the LEDs on the SRM on the BSR 64000 or the front panel of the BSR 1000 to determine if there is a fail condition or alarm. • If there is a fail condition and the SRM circuitry is not receiving power, replace the SRM on the BSR 64000. • If there is an alarm condition, check the modules on the BSR 64000 to determine which one is faulty. • If there is a fail condition on a BSR 1000, replace it.
BSR Troubleshooting Guide Table 2-1 describes the possible display states of these LEDs during operation. Table 2-1 Module LED Display States for the SRM Fail Status Alarm Interpretation Off Green Off Normal operating status. Off Green Red Failure. SRM is operating with an alarm condition. Red Off Off Indicates a module hardware failure. The LED is red when the BSR is receiving power, but there is no power to the circuitry. This can occur if a fuse on a BSR 64000 module is down.
Checking Physical Equipment Alarm LEDs Table 2-3 describes the BSR 64000 Alarm LEDs on the SRM. The SRM provides a set of three Alarm LEDs. These LEDs are visible on the module front panel of the SRM and are labeled: MIN (Minor), MAJ (Major), and CRIT (Critical).
BSR Troubleshooting Guide DOCSIS CMTS Resource Module LEDs The DOCSIS CMTS Module has two groups of LEDs that indicate its operational status: • • Module LEDs Per-Port LEDs The following subsections describe the possible display states of these LED types. Module LEDs The DOCSIS CMTS Module LEDs are visible on the module front panel and are labeled: Fail, Status, and Alarm. Table Table 2-4 describes the possible display states of these LEDs during operation.
Checking Physical Equipment Port LEDs are grouped vertically. A number to the right each LED group indicates the channel number associated with the group. The single downstream channel is numbered 0 and the four upstream channels are numbered 0, 1, 2, 3. Table 2-5 describes the possible display states of these LEDs during operation. Table 2-5 BSR 64000 Downstream and Upstream Port LED Display States Link Fail Interpretation Green Off Normal operating status.
BSR Troubleshooting Guide Table Table 2-4 describes the possible display states of these LEDs during operation. Table 2-6 Module LED Display States for the OC3/OC12 POS Resource Module Fail Status Alarm Interpretation Off Green Off Normal operating status. Off Green Red Failure. Module is operating with an alarm condition. Note: This sequence of LED occurs when an alarm condition is detected on individual upstream and downstream ports. Red Off Off Indicates a module hardware failure.
Checking Physical Equipment Port LEDs are grouped vertically. A number to the right each LED group indicates the port number associated with the group. Table 2-5 describes the possible display states of these LEDs during operation. Table 2-7 BSR 64000 OC3/OC12 POS Port and Ethernet LED Display States Link Fail Interpretation Green Off The SONET or Ethernet port is operational and is receiving and transmitting data. Green Red Operating with an alarm condition detected.
BSR Troubleshooting Guide Table 2-8 describes the possible display states of these LEDs during operation. Table 2-8 BSR 1000 System LED Display States Fail Status Alarm Interpretation Off Green Off Normal operating status. Off Green Red Failure. BSR 1000 is operating with an alarm condition. Note: This LED sequence occurs when an alarm condition is detected on individual upstream and downstream ports. Red Off Off Fuse failure possibly indicating a hardware failure. Red Off Red Failure.
Checking Physical Equipment Port LEDs are grouped vertically. A number above each LED group indicates the channel number associated with the group. The single downstream channel is numbered 0 and the four upstream channels are numbered 0, 1, 2, 3. Table 2-5 describes the possible display states of these LEDs during operation. Table 2-9 BSR 1000 Downstream and Upstream Port LED Display States Status Alarm Interpretation Green Off Normal operating status.
3 Monitoring SNMP
Monitoring SNMP Introduction This chapter describes how to use Simple Network Management Protocol (SNMP) information to monitor BSR system management networking activity. Displaying SNMP Information SNMP information lets you monitor management activities on the network. For example, SNMP traps are error messages sent from the SNMP agent to the SNMP manager to alert system administrators about Cable Modems (CMs) going offline or online.
BSR Troubleshooting Guide Table 3-1 Understanding SNMP show Information SNMP Information Explanation • Illegal operations for community names supplied Displays command operations that are not allowed for the existing community names. • ASN parse errors Displays the total number of Abstract Syntax Notation (ASN) errors found in SNMP messages received. • Requested variables Shows the requested SNMP variables. • Changed variables Shows the changed SNMP variables.
4 Troubleshooting the CMTS
Troubleshooting the CMTS Introduction This chapter provides troubleshooting solutions to some common Data Over Cable Service Interface Specifications (DOCSIS) network problems with the following: • • • • • Using Flap Lists to Troubleshoot CM Problems Resolving HFC Network Performance Problems Resolving Problems on the Upstream Path Resolving Problems on the Downstream Path Resolving Cable Modem Problems Using Flap Lists to Troubleshoot CM Problems The BSR maintains a database of flapping CMs to assist i
BSR Troubleshooting Guide • The CM upstream transmit power changes beyond the configured power adjust threshold. Follow these steps to view flap list statistics by using different sorting options: 1. To view all flap list statistics for CMs, use the show cable flap list command in Privileged EXEC mode as shown in the following example: RDN#show cable flap-list The following output displays: Figure 4-1 show cable flap-list Command Output 2.
Troubleshooting the CMTS The following output displays: Figure 4-3 show cable flap-list sort-time Command Output 4.
BSR Troubleshooting Guide Table 4-1 Flap List Command Output Identifications Field Identification Ins The Insertions Link process is used by a CM to perform an initial maintenance procedure to establish a connection with the BSR. The Ins column is the flapping CM’s (re) insertion count and indicates the number of times the a CM starts and inserts into the network in an abnormal way.
Troubleshooting the CMTS Initial maintenance @ Time T1 Station maintenance Init maintenance @ Time T2 The Ins and Flap counters in the flap list are incremented whenever T2 – T1 < N where N is the insertion-time parameter configured using the cable flap-list insertion-time command. The default value for this parameter is TBD seconds.
BSR Troubleshooting Guide Table 4-2 Troubleshooting CM Problems 4-46 Cause or Symptom Problem A CM has roughly the same number of hits and misses and contain a lot of insertions. There is a problematic downstream path. For example, the downstream power level to the CM may have a power level that is too low. A high flap list insertion (Ins) time number. Intermittent downstream synchronization loss. DHCP or CM registration problems.
Troubleshooting the CMTS Table 4-2 Troubleshooting CM Problems Cause or Symptom Problem High P-Adj (power adjustment) This condition can indicate that the fiber node is clipping the upstream return laser. Evaluate the CMs with the highest number of correcteds and uncorrecteds first. If the CMs are not going offline (Ins = 0), this will not be noticed by the subscriber. However, they could receive slower service due to dropped IP packets in the upstream.
BSR Troubleshooting Guide Table 4-3 describes how to interpret flap list statistics: Table 4-3 Flap List Statistic Interpretations Field Description Hit and Miss The HIT and MISS columns are keepalive polling statistics between the BSR and the CM. The station maintenance process occurs for every CM approximately every 10 seconds. When the BSR receives a response from the CM, the event is counted as a Hit. If the BSR does not receive a response from the CM, the event is counted as a Miss.
Troubleshooting the CMTS Table 4-3 Flap List Statistic Interpretations Field Description Flap The Flap counter indicates the number of times the CM has flapped. This counter is incremented when one of the following events is detected: Unusual CM insertion or re-registration attempts. The Flap and the Ins counters are incremented when the CM tries to re-establish the RF link with the BSR within a period of time that is less than the user-configurable insertion interval value.
BSR Troubleshooting Guide • Save the flap list statistics to a database server at least once a day to keep a record of flap list statistics which includes upstream performance and quality control data. These statistics can be used again at a later time to evaluate trends and solve intermittant problems on the HFC networks. Once the flap list statistics are backed up daily on the database server, the flap list statistics can be cleared.
Troubleshooting the CMTS 5. Do the following tasks to repair damaged contacts: • Ensure that contacts are made of similar metals. • Ensure that contacts are clean. • Ensure that contacts are securely fastened. • Replace or repair defective equipment, if necessary. Slow Performance Detected on Upstream Port Subscriber CMs connected to an upstream port are experiencing poor or slow performance.
BSR Troubleshooting Guide where: port is the number of the upstream port 4. To determine if modulation profile parameters are adequate for the upstream port, use the show cable modulation-profile command in Privileged EXEC mode as shown in the following example: RDN#show cable modulation-profile where: n is the modulation profile number being used. Figure 4-5 show cable modulation-profile Command Output 5.
Troubleshooting the CMTS If a new upstream modulation profile needs to be created, refer to the Configuring and Managing the BSR 64000 and Configuring and Managing the BSR 1000 documents for more information. 6. If there is no problem with the selected modulation profile, determine the signal quality on the upstream port.
BSR Troubleshooting Guide 7.
Troubleshooting the CMTS 8. View the signal quality statistics for the upstream interface. If there is a high number of unerroreds (uncorrupted packets), the upstream signal-quality is good. Table 4-4 describes the signal quality statistics: Table 4-4 Signal Quality Statistics Field Identification correctables Number of corrected error packets received through this upstream interface ifIndex Cable interface number unerroreds Number of unerrored packets on cable interface 9.
BSR Troubleshooting Guide 1. Check for bad optical amplifiers in the HFC network. 2. Check for defective equipment in the HFC network. 3. Determine if there is a cable that is physically cracked or damaged in such a way to cause external ingress from a variety of sources is entering into the network. 4. Look for loose connections. 5. Study the HFC network topology and look for flaws that may be causing additional ingress noise. 6. If there is too much ingress noise detected, increase the interleave depth.
Troubleshooting the CMTS Too Many CPE Hosts on Subscriber CM When too many Customer Premises Equipment (CPE) hosts, such as PCs, servers, and appliances are connected to a single subscriber’s CM, that CM can use an excessive amount of network resources compared to other CMs on the HFC subnetwork. Follow these steps to view the number of CPE hosts for a CM, and to limit that number: 1.
BSR Troubleshooting Guide Resolving Problems on the Upstream Path When the upstream port fault LED is red, the upstream port is not operating and is not receiving data from the CM subnetwork. Refer to the procedures in this section to troubleshoot an upstream port problem: • • Bad Upstream Signal-to-noise Ratio Detected Upstream Power Level Too Low or High Bad Upstream Signal-to-noise Ratio Detected If too much noise is detected on the upstream path a condition called noise funneling occurs.
Troubleshooting the CMTS interface is the number of the cable interface Note: The slot and interface number on the BSR 1000 are 0. port is the number of the upstream port 2. To view the modulation profile for the upstream port to determine whether QAM 16 or QPSK modulation is used on the upstream interface, use the show cable modulation-profile command in Privileged EXEC mode as shown in the following example: RDN#show cable modulation-profile where: n is the modulation profile number 3.
BSR Troubleshooting Guide 5. View the show cable interface signal-quality statistics for the specific upstream interface. If there is a high number of unerroreds (uncorrupted packets), the upstream signal-quality is good.
Troubleshooting the CMTS 1. Inspect optical amplifiers in the HFC network to make sure they are working properly. 2. Make sure all HFC network equipment is working properly. 3. Inspect cables for damage. 4. Secure all cable connections. 5. Review the HFC network topology and identify any flaws that may cause additional ingress. 6. Determine if there are too many nodes on an upstream port. Too much segmentation can affect the signal-to-noise ratio. 7.
BSR Troubleshooting Guide This section also describes how to configure the upstream input power level when problems occur. The upstream input power level is configured in either an absolute or relative mode. If the upstream input power level is set in relative mode, the input power level changes when the upstream channel width is changed. If the upstream input power level is set to the absolute mode, the input power level does not change when the upstream channel width is changed.
Troubleshooting the CMTS 3. Inspect amplifiers if there is an attenuation problem on the upstream path. View CMs that proceed or follow an amplifier in the upstream path to isolate the defective amplifier and replace or repair it. Look for amplifier degradation. Improperly configured amplifiers can degrade digital data signals. The larger the network, the higher the possibility of amplifier noise affecting the signals. 4. Be aware of thermal sensitivity.
BSR Troubleshooting Guide • • Bad Downstream Signal-to-Noise Ratio Detected Downstream Power Level Too Low or High Bad Downstream Signal-to-Noise Ratio Detected Follow these steps to identify problems associated with a bad downstream signal-to-noise ratio: 1.
Troubleshooting the CMTS • A high number of corrected packets and uncorrected, dropped packets occurs when the signal-to-noise ratio is approximately 25 dB for 256 QAM, and 20 dB for 64 QAM. You must manually troubleshoot and correct the problem. See if errors increment at a specific time at a higher than expected rate.
BSR Troubleshooting Guide 1. Check all downstream passive equipment (such as combiners, couplers, and attenuators) and cabling for flaws. The downstream signal may be weak because of a low power level on a portion of the downstream spectrum (88-860 MHz). This is known as a frequency response problem on the HFC network. The cause of a frequency response problem may be defective passive equipment, or damaged cable on the downstream path. 2.
Troubleshooting the CMTS 4. Inspect amplifiers if there is an attenuation problem on the downstream path. View CMs that proceed or follow an amplifier in the downstream path to isolate the defective amplifier and replace or repair it. Look for amplifier degradation. Improperly configured amplifiers can degrade digital data signals. The larger the network, the higher the possibility of amplifier noise affecting the signals. 5.
BSR Troubleshooting Guide 2. To verify that CM authentication is deactivated, use the show running-config command in Privileged EXEC mode and view the cable interface configuration information. The output will show if CM authentication is deactivated. RDN#show running-config 3.
Troubleshooting the CMTS “authentication string” is an alpha-numeric text string specified in double quotes 0xkey is a key specified in hexadecimal notation 5. To restore the default CM authentication, which is a null value, use the no cable shared-secret command in Interface Configuration mode, as shown in the following example: BSR64000(config-if)#no cable shared-secret [ <“authentication string”> | ] 6.
BSR Troubleshooting Guide slot is the slot number of the DOCSIS module on the BSR 64000 Note: The BSR 1000 uses the same syntax as the above command, however both the slot number and interface number are set to zero. interface is the number of the cable interface n is the SID number for the CM The SM Exhausted Count value in the command output refers to the number of times a CM was dropped because it did not reply to station maintenance requests.
Troubleshooting the CMTS 1. To ping a specific CM IP address or hostname to determine if the CM is online, use the ping command in Privileged EXEC mode, as shown in the following example: RDN#ping { | } where: ip-address is the IP address of the CM hostname is the DNS hostname of the CM Note: You must use a IP address for the CM you are pinging. If you cannot ping the CM using its IP address, the CM is not registering. 2.
BSR Troubleshooting Guide MAC-address is the MAC level address of the CM. ip-address is the IP level address of the CM. Note: It may take up to 30 seconds for the CM to respond and start the reset sequence. 5.
Troubleshooting the CMTS 3. If the CM has an IP address and must be reset, use the clear cable modem reset command in Privileged EXEC mode as shown in the following example: RDN#clear cable modem reset where: ip-address is the IP address of the CM 4. If all CMs are unable to obtain an IP address, use the clear cable modem all reset command to remove all CMs from the station maintenance list and reset them: RDN(config-if)#clear cable modem all reset 5.
BSR Troubleshooting Guide Provisioning Problems Cause CMs Not to Register It is important to understand the basic communication process between the CM, cable interface on the BSR, and the DHCP server to troubleshoot provisioning problems. The DHCP portion of the CM registration process works as follows: 1. The CM sends a broadcast discovery message to the DHCP server. 2.
Troubleshooting the CMTS 5. If the cable interface is receiving a DHCP discover message from the CM, determine if the cable interface is forwarding DHCP discover messages to the DHCP server by checking if the DHCP sever is receiving DHCP discover packets and if it is sending DHCP offer packets to the CM. a. If the DHCP server is receiving DHCP discover messages from the CM, the DHCP server can reply by sending a DHCP offer.
BSR Troubleshooting Guide 7. If there is no communication between the TFTP server and the cable interface, the CM does not have an IP address. Determine if TFTP parameters are set correctly on the cable interface.
Troubleshooting the CMTS 10. To reset all CMs so that they can obtain an IP address, use the clear cable modem all reset command in Privileged EXEC mode: RDN#clear cable modem all reset 11. If you have exhausted all the provisioning troubleshooting possibilities for CM registration problems, refer to other sections in this chapter for help on troubleshooting the upstream path from the CM to the cable interface.
BSR Troubleshooting Guide 4-78
5 Troubleshooting TCP/IP
Troubleshooting TCP/IP Introduction This chapter provides troubleshooting solutions to some common TCP/IP internetwork problems: • • • • • • • Resolving Host Connectivity Problems Handling Routing Problems Misconfigured Router Handling a Misconfigured Access List Access List and Filter Misconfigurations Handling UDP Broadcast Forwarding Problems Resolving PPP Link Over SONET Failures Resolving Host Connectivity Problems The following sections provide instructions for resolving local and remote host conn
BSR Troubleshooting Guide Follow these steps to configure a default gateway for a local or remote host: 1. To determine whether the local and remote hosts have a default gateway, use the netstat -rn command at the UNIX prompt, as shown in the following example: unix-host% netstat -rn Check the output of this command for a default gateway specification. 2.
Troubleshooting TCP/IP 2. The default route entry should specify the router that has the route to the remote host. If there is no default route entry, use the route add default command at the UNIX prompt to manually configure the default gateway: unix-host% route add default where: ip-address is the IP address of the default gateway (the router local to the host). n indicates the number of hops to the specified gateway. Note: You may need to reboot the host for this change to take effect.
BSR Troubleshooting Guide DNS Not Running If issuing the host command at the UNIX prompt returns a Host not found message, but you are able to open a connection using the host’s IP address, the DNS might not be running. Consult the DNS software documentation or your system administrator for information on configuring and enabling the DNS.
Troubleshooting TCP/IP Table 5-1 traceroute Command Output Field Descriptions Field Description Q Source quench. P Protocol unreachable. N Network unreachable. U Port unreachable. H Host unreachable. 2. Once you isolate a problem router, determine whether routing is enabled on the BSR.
BSR Troubleshooting Guide 6. To enable the proper routing protocol on the router interface, use the router command in Global Configuration mode, as shown in the following example. The following example shows how to enable the RIP routing protocol on the router interface. RDN(config)#router rip Note: The Autonomous System (AS) number needs to be entered when enabling BGP. The AS applies to BGP only. 7.
Troubleshooting TCP/IP 4. To view a specific router configuration, use the show running-config command in Privileged EXEC mode. 5. Try to ping another device that is on the same network that has a routing problem. 6. Make sure that there is a network router configuration command specified for the network to which the interface belongs. For example, if you assign the new interface IP address 10.10.10.
BSR Troubleshooting Guide interface number refers to the ethernet or POS interface number. Note: The BSR 1000 uses the same syntax as the above command, however the ethernet interface slot and interface number are set to zero. RDN(config-if)#no shutdown 3. To discover if the router interface is enabled, use the show ip interfaces brief command in Privileged EXEC mode. If the interface is still down, there might be a hardware or media problem.
Troubleshooting TCP/IP Handling a Misconfigured Access List Access lists are used to filter IP packets so that certain IP packets are denied or permitted. Follow these steps to troubleshoot a misconfigured access list: 1. To determine whether IP packets are being sent and received and whether there are encapsulation problems, use the debug ip packet command in Privileged EXEC mode. Caution: Debug commands can use considerable CPU resources on the router.
BSR Troubleshooting Guide RDN(config-if)#no ip access-group access-list [extended | standard] where: group number is the ip access group extended or standard is selected for an access list list number is the access list number 5. Execute the debug ip packet command to determine whether the router is receiving packets. 6. If the router is receiving packets an access list is probably filtering packets.
Troubleshooting TCP/IP 9. If packets pass normally, perform steps 1 to 7 on any other routers in the path until all access lists are enabled and packets are forwarded properly. Access List and Filter Misconfigurations Application errors that drop host connections are frequently caused by misconfigured access lists or other filters. Follow these steps to fix access lists or other filters: 1. Use the show running-config command in Privileged EXEC mode to check each router in the path.
BSR Troubleshooting Guide 7. If you altered an access list, enable the list to see whether the application can still operate normally. 8. If the application operates normally, repeat the previous steps to isolate any other problem access lists until the application operates correctly with all access lists enabled. Handling UDP Broadcast Forwarding Problems The User Datagram Protocol (UDP) describes how messages reach application programs within a destination computer.
Troubleshooting TCP/IP 4. Look for an ip helper-address command entry for that router interface. Make sure that the specified address is correct (it should be the IP address of a server application such as a BOOTP server). If there is no command entry, no helper address is configured. 5. If there is no IP helper address configured, or if the wrong address is specified, add or change the helper address using the ip helper-address interface configuration command. For example, to configure the IP address 10.
BSR Troubleshooting Guide Resolving PPP Link Over SONET Failures This section discusses how to troubleshoot a problem Point to Point Protocol (PPP) link on the POS module. Follow these steps to troubleshoot the PPP link: 1. To check the link state and running information about the PPP link, use the show ip interface brief command in Privileged EXEC mode, as shown in the following example: RDN#show ip interface brief 2.
Troubleshooting TCP/IP 6. To determine if there is no network activity at the IP layer between the local and remote devices, use the debug ppp ipcp command in POS Interface Configuration mode, as shown in the following example: RDN(config-if)#debug ppp ipcp 7. If there are problems at the IP layer, such as a wrong routing configuration, use the show ip route command in Privileged EXEC mode to view the status of a route with the IP address of the destination device and its connection to the POS module.
BSR Troubleshooting Guide RDN(config)#show interface pos Determine if there is a high amount of errors occurring on the other SONET device. 13. Determine which configuration parameters need to be reconfigured to solve the packet error problems. 14. If you have examined all possible PPP link problems, and believe the problem is related to the SONET connection, refer to Chapter 9 for information on troubleshooting the SONET connection.
6 Troubleshooting RIP
Troubleshooting RIP Introduction This chapter provides troubleshooting solutions to some common Routing Information Protocol (RIP) problems: • • Handling Routing Table Problems Handling RIP Version Inconsistencies Handling Routing Table Problems Problems that occur when hosts on one network cannot access hosts on another network may occur on an internetwork running only RIP.
BSR Troubleshooting Guide Misconfigured Route Filtering If route filtering is misconfigured, it prevents a RIP router from receiving routing table updates or prevents a RIP router from transmitting routing table updates. Follow these steps to discover and resolve misconfigured route filters: 1. Use the show running-config command to examine the suspect BSR. 2. See if any distribute-list in or distribute-list out command is configured in Router Configuration mode on the BSR.
Troubleshooting RIP Split Horizon is Disabled If routing loops are occurring between neighboring RIP routers or the size of routing updates to routing tables are large, the problem may be that split horizon is disabled. Follow these steps to enable split horizon: 1. To determine if split horizon is disabled, use the show ip route command in Privileged EXEC mode on the remote router. 2. View the Split horizon is enabled message in the show ip route command output. 3.
BSR Troubleshooting Guide Follow these steps to ensure that the correct version of RIP is running on the BSR: 1. To determine which version of RIP is configured on the BSR, use the debug ip rip command in RIP Configuration mode, as shown in the following example: RDN(config-rip)#debug ip rip 2. Review the debug ip rip command output and identify the cause of the problem. Use no debug ip rip to turn off debugging. 3.
Troubleshooting RIP Table 6-2 lists the available command options. Table 6-2 ip rip send version Command Options Option Description 0 The BSR can send RIP version 1 and 2 packets. 1 The BSR can send only RIP version 1 packets. 2 The BSR can send only RIP version 2 packets. 5. To verify that the correct version of RIP is configured on the BSR, use the show running-config command in Privileged EXEC mode.
BSR Troubleshooting Guide interface number refers to the ethernet interface number. Note: The BSR 1000 uses the same syntax as the above command, however the ethernet interface slot and interface number are set to zero. 4. To change the version of RIP received over the specified interface, use the ip rip receive version command in Interface Configuration mode, as shown in the following example: RDN(config-if)#ip rip receive version
Troubleshooting RIP Table 6-4 lists the available command options. Table 6-4 ip rip send version Command Options Option Description 0 The specified interface can send RIP version 1 and 2 packets. 1 The specified interface can send only RIP version 1 packets. 2 The specified interface can send only RIP version 2 packets. 6. To verify that the correct version of RIP is configured on the specified interface, use the show running-config command in Privileged EXEC mode.
7 Troubleshooting OSPF
Troubleshooting OSPF Introduction This chapter provides troubleshooting solutions to some common Open Shortest Path First (OSPF) routing protocol problems: • • • Handling OSPF-designated Interface Problems Handling Router Neighbor Misconfigurations Resolving Missing Routes in Routing Table Handling OSPF-designated Interface Problems OSPF uses an IP address on the BSR as its router ID.
BSR Troubleshooting Guide Handling Router Neighbor Misconfigurations The following sections explain why OSPF routers may not exchange information to establish neighbor relationships: • • Misconfigured Router Mismatched OSPF Parameters Misconfigured Router Follow these steps to resolve a misconfigured or missing network router command: 1. Use the show ip ospf interfaces command in Privileged EXEC mode to determine which interfaces have OSPF enabled. 2.
Troubleshooting OSPF 5. Check other OSPF routers on the network by repeating steps 1 to 4. Make sure that OSPF is configured properly on all neighboring routers so that neighbor relationships can be established. Mismatched OSPF Parameters The Hello or dead timers, E-bits (set for stub areas), N-bits that are set for Not-So-Stubby Areas (NSSAs), area IDs, authentication types, or network mask parameters may be mismatched.
BSR Troubleshooting Guide 4. Use the debug ip ospf adj command in Privileged EXEC mode. Check the output for mismatched values, as shown in the following example: RDN#debug ip ospf adj 5. If mismatches are indicated in the debug output, try to resolve the mismatch. 6. Ensure that all routers in an area have the same area ID and authentication type, and are configured as stub routers.
Troubleshooting OSPF 4. Look in the show ip interface command output for a message for a specific interface that is similar to the one in the following example: ethernet 7/0 is up, line protocol is up Internet address is 10.10.20.143/16 Broadcast address is 255.255.255.
BSR Troubleshooting Guide The following sections describe how to resolve missing OSPF routes in a routing table: • • RIP Routing Information Incorrectly Redistributed into OSPF ABR Configured Without Area 0 Interface RIP Routing Information Incorrectly Redistributed into OSPF Follow these steps to redistribute RIP routing information into OSPF: 1. To check the router configuration, use the show running-config command in Privileged EXEC mode. 2.
Troubleshooting OSPF ABR Configured Without Area 0 Interface If there are two or more OSPF networks, both should be configured with a different area ID, and at least one OSPF network must have an area ID of 0. Follow these steps to configure an OSPF Area Border Router (ABR) with an Area 0 interface: 1. To verify that at least one ABR exists for the area, use the show running-config command in Privileged EXEC mode on OSPF routers. ABRs must belong to area 0, which is the OSPF backbone and one other area.
BSR Troubleshooting Guide 3. To configure an ABR if one does not exist in an area, use the network command in Router Configuration mode. For example, to configure OSPF router 100 to participate in the OSPF backbone area, follow these commands: RDN(config)#router ospf RDN(config-ospf)#network 10.10.3.7 0.0.0.
8 Troubleshooting BGP
Troubleshooting BGP Introduction This chapter provides troubleshooting solutions to some common Border Gateway Protocol (BGP) routing protocol problems: • • Handling BGP Routing Problems Handling BGP Peer Misconfigurations Handling BGP Routing Problems Follow these sections to correct BGP routes missing from the routing table so that the BGP router and network are advertised to other routers. Missing Neighbor Table Entry Follow these steps to add entries to the BGP neighbor routing table: 1.
BSR Troubleshooting Guide Misconfigured Access List Follow these steps to resolve access list configuration problems: 1. Use the show access-list command in Privileged EXEC mode on suspect routers to determine if there are access lists configured and enabled on the router. 2. If there are access lists enabled on the router, disable them using the appropriate commands. For example, to disable input access list 10, follow this command: RDN(config)#no ip access-group 10 in 3.
Troubleshooting BGP Missing Network Destination Advertisement When BGP routers do not advertise routes, routing updates from those routers do not contain information about certain network destinations that should be advertised. Follow these steps to solve BGP advertising routing problems: 1. To view the router configuration, use the show running-config command in Privileged EXEC mode. 2.
BSR Troubleshooting Guide RDN(config-bgp)#neighbor{ip-address | peer-group-name} remote-as number where: ip-address is the IP address of the neighbor peer-group-name is the name of the BGP peer group number is the AS to which the neighbor belongs 3.
Troubleshooting BGP 6. To view route entries in the route table (also known as the forwarding table), use the show ip route command in Privileged EXEC mode, as shown in the following example: RDN#show ip route 7. If you suspect that the local BGP router is not receiving some routes, use the show running-config command in Privileged EXEC mode, as shown in the following example: RDN#show running-config 8.
9 Troubleshooting SONET
Troubleshooting SONET Introduction This chapter describes how to troubleshoot the Packet Over SONET (POS) access module. When SONET network problems occur, the major failure conditions and their associated alarm indicators occur.
BSR Troubleshooting Guide 4. If LEDs on the POS module are green but you suspect that the module is has transmission problems on a port (causing an LOS on the other SONET device receive port), check for a Line Alarm Indication Signal (L-AIS) or Line Remote Defect (Degrade) Indication (L-RDI) failure. To do so, view the Active Defect field in the show controllers pos command output.
Troubleshooting SONET LOF Determination The SONET port may not operate if a Loss of Frame (LOF) condition occurs. LOF conditions occur when there is no valid framing pattern for 3 milliseconds. When a LOF condition on a POS module port occurs, follow these steps to determine the LOF condition: 1. Locate the SONET termination equipment. 2.
BSR Troubleshooting Guide 3. Check for signal degradation. 4. Check fiber optic connectors are broken or unclean. 5. Check the fiber cabling for damage or improper use. For example, SONET cables may be turned beyond their bending radius. LOP Determination The SONET port may not be operational because there is a Loss of Pointer (LOP) condition that occurs when there is the absence of valid H1/H2 pointer bytes for eight, nine, or ten consecutive frames.
Troubleshooting SONET 6. Check for a Path Remote Error Indication (P-REI) failure by viewing the Active Defect field in the show controllers pos command output. A P-REI failure is generated by the SONET device and sent out its transmit port when a failure is detected on its receive port. A P-REI indicates a LOP failure condition, and indicates high bit error rates coming from the transmitting (upstream) device. Refer to the section Handling Data Loss on SONET Link for more information.
BSR Troubleshooting Guide 1. Check for bent pins on the backplane. 2. If there are no bent pins, replace the POS module with a new POS module, or try inserting the POS module in a different slot. If the POS module works in a different slot, the BSR 64000 backplane may be defectivel Handling Data Loss on SONET Link Data loss can occur on a section, line, or path of a SONET link: • A section may be between Customer Premises Equipment (CPE) and SONET Service Provider Equipment (SPE).
Troubleshooting SONET 4. Use the information in Table 9-1 to troubleshoot b1-tca, b2-tca, and b3-tca information that indicates where the data loss may be occurring on a SONET section, line, or path. Table 9-1 Data Loss Error Descriptions Error Description b1-tca Associated with a specific SONET section. B1 errors indicate a LOS or LOF condition. Reports a B1 bit error rate (BER) threshold crossing alarm.
BSR Troubleshooting Guide Data Loss Resolution Once you isolate a specific SONET section, line, or path, follow these steps to resolve the problem: 1. Check the fiber cabling for damage or improper use. For example, SONET cables may be turned beyond their bending radius. 2. Check for signal degradation. 3. Check fiber optic connectors for damage, and make sure they are clean. 4.
A Cable Modem Registration Process
Cable Modem Registration Process Introduction This appendix describes the cable modem registration process. A cable modem goes through a standard registration process as defined by the Data Over Cable Service Interface Specification (DOCSIS) to successfully connect to the BSR 1000 CMTS and the BSR 64000 DOCSIS 1:4 and DOCSIS 2:8 CMTS modules on the CM network.
BSR Troubleshooting Guide • Station Maintenance ranging uses periodic time intervals to send a unicast message containing a registered SID between the cable modem and the CMTS. • Short Data Grants and Long Data Grants are grants of time that a cable modem with a particular SID has to transmit upstream. The cable modem establishes downstream synchronization with the CMTS.
Cable Modem Registration Process • Cable modem Subnet Mask. • TFTP server IP address used to connect to the TFTP server. • Download Configuration file name is the name of the cable modem configuration file to be read from the TFTP server by the cable modem. • Cable Modem Lease Time used for keeping the correct time on error logs. Establishing Time of Day For security purposes, the cable modem obtains its IP parameters from the DHCP server and it establishes the Time of Day (TOD).
BSR Troubleshooting Guide Baseline Privacy Baseline Privacy encrypts upstream and downstream data passed between the cable modem and CMTS using the shared Authentication Key (AK) and Traffic Encryption Key(s) (TEKs). The CMTS assigns an AK to a cable modem based on the cable modem SID. The CMTS AK can be set to expire based on a grace-time or a lifetime value. The TEK is assigned to a cable modem once the cable modem has a valid AK. The TEK encrypts data traffic between the cable modem and the CMTS.
Cable Modem Registration Process Data Exchange Cable modems use the dedicated data intervals in the current upstream MAPs to transmit data to the CMTS. When no dedicated data interval in the current upstream bandwidth allocation map exists and the Protocol Data Unit (PDU) data frame is within the appropriate size range, cable modems compete for request and data contention intervals to transmit data to the CMTS.
Index A access lists, 89 to 91 BGP, 120 RIP, 100 common path distortion, 50 controlling upstream input power level, 61 correctables, 55 active alarm field, 127 CPE, 57, 132 amplifier noise, 67 CRC level mismatch, 95 application errors, 91 customer premises equipment see CPE area border router (ABR) see OSPF D audible alarm, clearing, 27 Autonomous System (AS), 86 default gateway, 81 to 83 B default power-level range, 62 BGP, 119 to 123 AS path access lists, 123 autonomous system numbers, 119 c
BSR Troubleshooting Guide H L-RDI, 128, 129, 130 H1/H2 pointer bytes, 130 M I MAC layer, 95 ingress noise, 56, 65 electrical, 56 impulse, 56 maximum transmission unit see MTU micro reflections, 55, 60 input power-level range, 62 MTU, 112 interleave depth setting, 56 N IP address problems, 72, 73 NCPs, 94 IP helper address, 93 network control protocols see NCPs L network problems, 41 L-AIS, 128, 129, 130 noise funneling, 58 laser clipping, 65, 66 O LED displays, 31 downstream port, 32
POS fail LED, 131 to 132 LOF LED, 129 LOP LED, 130 LOS LED, 127 SNMP, 37 cable modem response to, 77 power level downstream, 66 SONET, 127 to 134 b1-tca, 133 b2-tca, 133 b3-tca, 133 device, 95 PPP, 94 SPE, 132 P-REI, 131 split horizon, 101 provisioning problems, 74 SRM (Supervisory Routing Module), 25 Q QAM, 59, 60 16 QAM, 55 256 QAM, 64 64 QAM, 64 QPSK, 55, 60 station maintenance requests, 69 system LED displays, 31 T TCP ports, 120 thermal sensitivity, 67 quadrature amplitude modulation see Q
