Apple Talk Connections to Services Drop

Symptom Users complain that their AppleTalk sessions suddenly drop for no apparent reason. Table 9-8 outlines the problem that might cause this symptom and describes solutions to that -problem. Table 9-8 AppleTalk Connections to Services Drop Table 9-8 AppleTalk Connections to Services Drop Excessive traffic load on internetworks with many routers can prevent some routers from sending RTMP updates every 10 seconds as they should. Because routers begin to age out routes after missing two...

Apple Talk Enhanced IGRP Routes Missing from Routing Table

Symptom Routes are missing from the routing table of routers running AppleTalk Enhanced IGRP. Clients (Macintosh computers) on one network cannot access servers on a different network. Clients might or might not be able to connect to servers on the same network. The problem might occur in internetworks running only Enhanced IGRP or in an internetwork running Enhanced IGRP and RTMP. Table 9-13 outlines the problems that might cause this symptom and describes solutions to those problems. Table...

Apple Talk Network Services Intermittently Unavailable

Symptom Network services are intermittently unavailable. Services come and go without warning. Table 9-6 outlines the problems that might cause this symptom and describes solutions to those problems. Table 9-6 AppleTalk Network Services Intermittently Unavailable Table 9-6 AppleTalk Network Services Intermittently Unavailable Duplicate network numbers or overlapping cable-range In AppleTalk, network numbers must be unique within an internetwork. If duplicate network numbers exist, packets might...

Apple Talk Technology Basics

AppleTalk was designed as a client server distributed network system. In other words, users share network resources (such as files and printers) with other users. Computers supplying these network resources are called servers computers using a server's network resources are called clients. Interaction with servers is essentially transparent to the user because the computer itself determines the location of the requested material and accesses it without further information from the user. In...

Apple Talk Users Cannot Access Zones or Services

Symptom Users cannot access zones or services that appear in the Chooser. Users might or might not be able to access services on their own network. Table 9-2 outlines the problems that might cause this symptom and describes solutions to those problems. Table 9-2 AppleTalk Users Cannot Access Zones or Services Table 9-2 AppleTalk Users Cannot Access Zones or Services Step 1 Use the show appletalk interface exec command. Check the output for a port configuration mismatch message. If the command...

Apple Talk Zones Missing from Chooser

Symptom Certain zones do not appear in the Chooser. The zones are not visible from multiple networks. In some cases, when the Chooser is opened, the zone list changes. Table 9-4 outlines the problems that might cause this symptom and describes solutions to those problems. Table 9-4 AppleTalk Zones Missing from Chooser Step 1 Use the show appletalk interface exec command. Check the output for a port configuration mismatch message. If the command output contains a mismatch message, the router...

Ara Ara Client Unable to Connect to ARA Server

Symptom An ARA client (such as a Macintosh) attempts to connect to an ARA server (such as a Cisco access server) and cannot initiate a remote session. The user might be able to connect briefly, but the connection is immediately terminated. Table 9-18 outlines the problems that might cause this symptom and describes solutions to those problems. Table 9-18 ARA ARA Client Unable to Connect to ARA Server Table 9-18 ARA ARA Client Unable to Connect to ARA Server Step 1 Use the show running-config...

ARA Connection Hangs After Communicating At Message

Symptom An ARA client (for example, a Macintosh) tries to connect to an ARA server (such as a Cisco access server) over client and server modems. The client receives a connect message such as Communicating at 14.4 Kbps but then hangs for 10-30 seconds and finally shows a connection failed message. Table 9-19 outlines the problem that might cause this symptom and describes solutions to that problem. Table 9-19 ARA Connection Hangs After Communicating At Message Table 9-19 ARA Connection Hangs...

ARA Slow Performance from Dialin Connection

Symptom Performance on remote dialin ARA sessions is slow. Table 9-21 outlines the problem that might cause this symptom and describes solutions to that problem. Table 9-21 ARA Slow Performance from Dialin Connection Table 9-21 ARA Slow Performance from Dialin Connection Flow control is not enabled, is enabled only on one device (either DTE or DCE), or is misconfigured Step 1 Configure hardware flow control on the line using the flowcontrol hardware line configuration command. Hardware flow...

AURP Routes Not Propagated Through AURP Tunnel

Symptom AppleTalk routes are not propagated through an AURP tunnel. Routes that are known to exist on one side of the tunnel do not appear in the routing tables of the exterior router on the other side of the tunnel. Changes on the remote network (such as a route going down) are not learned by the exterior router on the other side of the tunnel. Table 9-16 outlines the problems that might cause this symptom and describes solutions to those problems. Table 9-16 AURP Routes Not Propagated Through...

BGP Routes Missing from Routing Table

Symptom BGP routers and networks are not advertised to other routers. Routers do not receive routing information from other routers. Some hosts cannot communicate with hosts in other areas, and routing table information is incomplete. Table 7-16 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-16 BGP Routes Missing from Routing Table Table 7-16 BGP Routes Missing from Routing Table If BGP routers are not advertising routes properly, routing...

Digital Network Architecture

Contrary to popular belief, DECnet is not a network architecture at all but is, rather, a series of products conforming to Digital's Digital Network Architecture (DNA). Like most comprehensive network architectures from large systems vendors, DNA supports a large set of both proprietary and standard protocols. The list of DNA-supported technologies grows constantly as Digital implements new protocols. Figure 11-1 illustrates an incomplete snapshot of DNA and the relationship of some of its...

Frame Format

The SDLC frame format is shown in Figure 10-1. if tyitr i 1 or 2 1 or 2 Variable 2 1 if tyitr i 1 or 2 1 or 2 Variable 2 1 As Figure 10-1 shows, SDLC frames are bounded by a unique flag pattern. The address field always contains the address of the secondary involved in the current communication. Because the primary is either the communication source or destination, there is no need to include the address of the primary it is already known by all secondaries. The control field uses three...

General Problem Solving Model

When you're troubleshooting a network environment, a systematic approach works best. Define the specific symptoms, identify all potential problems that could be causing the symptoms, and then systematically eliminate each potential problem (from most likely to least likely) until the symptoms disappear. Figure 1-1 illustrates the process flow for the general problem-solving model. This process flow is not a rigid outline for troubleshooting an internetwork it is a foundation from which you can...

Internet Group Membership Protocol

Internet Group Membership Protocol (IGMP), defined in RFC 1112, relies on Class D IP addresses for the creation of multicast groups. By using a specific Class D address, an individual host dynamically registers itself in a multicast group. Hosts identify their group memberships by sending IGMP messages. Traffic is then sent to all members of that multicast group. Routers listen to IGMP messages and periodically send out queries to discover which groups are active on which LANs. To build...

Internetworking Terms and Acronyms

Cisco Systems Terms and Acronyms Copyright 1989-2000 Cisco Systems Inc. Cisco - Feedback Content-Type text html Cisco - Feedback Content-Type text html Did this (or your previous) CCO visit save you a call to Cisco Your feedback is vital to our goal of making CCO the most useful and informative website on the planet. Please let us know how we are doing and, more importantly, what we can improve. CCO's breadth of information & services CCO's perceived speed or responsiveness Overall...

IP Enhanced IGRP Router Stuck in Active Mode

Symptom An IP Enhanced IGRP router is stuck in Active mode. Multiple Stuck-in-Active messages are sent to the console DUAL-3-SIA Route 198.169.52.51 Stuck-in-Active For a more detailed explanation of Enhanced IGRP Active mode, see the section Enhanced IGRP and Active Passive Modes later in this chapter. Note Occasional messages of this type are not a cause for concern. This is how an Enhanced IGRP router recovers if it does not receive replies to its queries from all its neighbors. However, if...

IPX Enhanced IGRP No Connectivity over IPX Enhanced IGRP Router

Symptom IPX Enhanced IGRP routers are blocking connections. Clients cannot connect to servers over one or more routers running IPX Enhanced IGRP. Note Procedures for troubleshooting connectivity problems not specific to IPX Enhanced IGRP routing are described in the section Novell IPX Client Cannot Connect to Server on Remote LAN earlier in this chapter. Table 8-8 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-8 IPX Enhanced IGRP No...

IPX Enhanced IGRP Routers Not Establishing Neighbors

Symptom IPX Enhanced IGRP routers do not establish neighbors properly. Routers that are known to be connected do not appear in the neighbor table. Note Procedures for troubleshooting IPX Enhanced IGRP problems not specific to establishing neighbors are described in the section 'IPX Enhanced IGRP No Connectivity over IPX Enhanced IGRP Router earlier in this chapter. Table 8-9 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-9 IPX Enhanced...

Local SRB Host Cannot Connect to Server

Symptom Connections fail over a router configured as an SRB connecting two or more Token Rings. Table 10-1 outlines the problems that might cause this symptom and describes solutions to those problems. Table 10-1 Local SRB Host Cannot Connect to Server Table 10-1 Local SRB Host Cannot Connect to Server A router interface configured for bridging fails to insert into a ring when it detects a ring number mismatch, and posts an error message to the console. Step 1 Get the ring number (specified in...

Media Problems Token Ring

Table 6-1 outlines problems commonly encountered on Token Ring networks and offers general guidelines for solving those problems. Table 6-1 Media Problems Token Ring Table 6-1 Media Problems Token Ring Step 1 Use the show interfaces token command to determine the status of the router's Token Ring interfaces. Step 2 If the status line indicates that the interface and line protocol are not up, check the cable from the router to the MAU.1 Make sure that the cable is in good condition. If it is...

Navigating Cisco Connection Documentation CDROM

Cisco Connection Documentation CD-ROM is a series of interconnected documents that you navigate by clicking on hypertext links and using the navigation tools---the toolbar, the navigation bar, and the document button bar. In addition, Cisco Connection Documentation CD-ROM offers a powerful search facility to allow you to jump directly to the information that interests you. Cisco Connection Documentation CD-ROM also provides several ways to return to documents that you have previously looked at....

Novell IPX Client Cannot Connect to Server on Remote LAN

Symptom Clients cannot make connections to servers on another network over one or more routers interconnected by LAN networks. Clients can connect to servers on their local network. Table 8-2 outlines the problems that might cause this symptom and describes solutions to those problems. Note If clients cannot connect to servers on their local network, refer to the section Novell IPX Client Cannot Connect to Server on Same LAN earlier in this chapter. If there is a WAN network between the local...

Novell IPX Client Cannot Connect to Server on Same LAN

Symptom Clients cannot make connections to servers located on the same LAN. Also, clients cannot connect to servers on remote networks. Table 8-1 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-1 Novell IPX Client Cannot Connect to Server on Same LAN Table 8-1 Novell IPX Client Cannot Connect to Server on Same LAN Step 1 Make sure the software on both clients and servers is the current version, is configured correctly, and has loaded...

Novell IPX Clients Cannot Connect to Server over PSN

Symptom Clients cannot connect to servers over a packet-switched network (PSN), such as Frame Relay, X.25, or SMDS. Clients can connect to local servers. Note Procedures for troubleshooting connectivity problems not specific to PSN environments are described in the section Novell IPX Client Cannot Connect to Server on Remote LAN earlier in this chapter. Table 8-3 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-3 Novell IPX Client Cannot...

Novell IPX Intermittent Connectivity

Symptom Connectivity between clients and servers is intermittent. Clients might be able to connect some of the time, but at other times no connectivity to certain servers or networks is possible. Table 8-12 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-lZ Novell IPX Intermittent Connectivity Table 8-lZ Novell IPX Intermittent Connectivity Step 1 Use the show running-config privileged exec command to view the router configuration. Look for...

Novell IPX Slow Performance

Symptom Slow network performance is experienced in a Novell IPX network. Table 8-13 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-lS Novell IPX Slow Performance Table 8-lS Novell IPX Slow Performance Novell servers not processing SAP updates as quickly as router is generating them Step 1 Use the show interfaces privileged exec command to check for output drops. Step 2 If there are excessive drops, use the show ipx servers exec command on...

Novell NetBIOS Applications Cannot Connect to Server over Router

Symptom Applications that use Novell NetBIOS (such as Windows 95) cannot connect to servers over a router. Clients cannot connect to servers on the same LAN. Table 8-5 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-5 Novell NetBIOS Applications Cannot Connect to Server over Router Table 8-5 Novell NetBIOS Applications Cannot Connect to Server over Router Missing ipx type-20-propagation commands Step 1 Use the debug ipx packet privileged...

OSPF Routers Not Establishing Neighbors

Symptom OSPF routers are not establishing neighbor relationships properly. The result is that routing information is not exchanged between routers. Table 7-11 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-11 OSPF Routers Not Establishing Neighbors Table 7-11 OSPF Routers Not Establishing Neighbors Step 1 Use the show ip ospf interfaces exec command to determine which interfaces have OSPF1 enabled. Step 2 If the output indicates that an...

RSRB Host Cannot Connect to Server Peers Not Open

Symptom Hosts cannot make connections to servers across a router configured as a remote source-routing bridge (RSRB). The output of the show source-bridge privileged exec command shows that SRB peers are not open. Note If you succeed in getting peers to open but hosts are still unable to communicate with servers, refer to the section RSRB Host Cannot Connect to Server (Peers Open) later in this chapter. Table 10-3 outlines the problems that might cause this symptom and describes solutions to...

RSRB Host Cannot Connect to Server Peers Open

Symptom Hosts cannot make connections to servers across a router configured as an RSRB. The output of the show source-bridge privileged exec command shows that SRB peers are open. The following is an example of output from the show source-bridge command Peers state lv pkts_rx pkts_tx expl_gn drops TCP TCP 150.136.93.93 open 2* 18 18 3 0 0 Table 10-4 outlines the problems that might cause this symptom and describes solutions to those problems. Table 10-4 RSRB Host Cannot Connect to Server (Peers...

RSRB NetBIOS Client Cannot Connect to Server

Symptom NetBIOS clients cannot connect to NetBIOS servers over a router configured as an RSRB. Table 10-6 outlines the problems that might cause this symptom and describes solutions to those problems. Table 10-6 RSRB NetBIOS Client Cannot Connect to Server Table 10-6 RSRB NetBIOS Client Cannot Connect to Server Step 1 For each router on which NetBIOS name caching is enabled, use the show rif exec command to determine whether the RIF entry shows the correct path from the router to both the...

Sample Display

The following is sample output from the show interfaces tokenring command Router show interfaces tokenring TokenRing 0 is up, line protocol is up Hardware is 16 4 Token Ring, address is 5500.2000.dc27 (bia 0000.3000.072b) Internet address is 150.136.230.203, subnet mask is 255.255.255.0 MTU 8136 bytes, BW 16000 Kbit, DLY 630 usec, rely 255 255, load 1 255 Encapsulation SNAP, loopback not set, keepalive set (10 sec) ARP type SNAP, ARP Timeout 4 00 00 Ring speed 16 Mbps Single ring node, Source...

SDLC Router Cannot Communicate with SDLC Device

Symptom Router cannot communicate with an IBM SDLC device. Table 10-9 outlines the problems that might cause this symptom and describes solutions to those problems. Table 10-9 SDLC Router Cannot Communicate with SDLC Device Table 10-9 SDLC Router Cannot Communicate with SDLC Device Step 1 Use the show interfaces exec command to determine whether the interface and line protocol are up. Step 2 If the interface and line protocol are both up, troubleshoot link-layer problems as described later in...

Serial Lines Increasing Input Errors in Excess of 1 of Total Interface Traffic

If input errors appear in the show interfaces serial output (refer to Figure 15-1), there are several possible sources of those errors. The most likely sources are summarized in Table 15-4. Note Any input error value for cyclic redundancy check (CRC) errors, framing errors, or aborts above 1 percent of the total interface traffic suggests some kind of link problem that should be isolated and repaired. Symptom Increasing number of input errors in excess of 1 percent of total interface traffic....

Serial Lines Troubleshooting Serial Line Input Errors

Table 15-5 describes the various types of input errors displayed by the show interfaces serial command (see Figure 15-1), possible problems that might be causing the errors, and solutions to those problems. Table 15-5 Serial Lines Troubleshooting Serial Line Input Errors Table 15-5 Serial Lines Troubleshooting Serial Line Input Errors CRC errors occur when the CRC calculation does not pass (indicating that data is corrupted) for one of the following reasons Serial cable is too long or cable...

Table of Contents

Cisco Connection Documentation CD-ROM Help What is Cisco Connection Documentation CD-ROM Cisco Connection Documentation CD-ROM User Interface Navigating Cisco Connection Documentation CD-ROM Hypertext Links Table of Contents Illustrations Tables Searching the Current Document Searching Multiple Documents Configuring Adobe Acrobat Reader as a Helper Application

TCPIP Host Connections Fail Using Certain Applications

Symptom Connection attempts using some applications are successful, but attempts using other applications fail. For instance, you might be able to ping a host successfully, but Telnet connections fail. Table 7-6 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-6 TCP IP Host Connections Fail Using Certain Applications Table 7-6 TCP IP Host Connections Fail Using Certain Applications Misconfigured access lists or other filters Step 1 Use the...

TCPIP Local Host Cannot Access Remote Host

Symptom Hosts on one network cannot communicate with hosts on a remote network. The networks are separated by one or more routers and might include WAN or other links. One or more routing protocols are running on the routers. Table 7-3 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-3 TCP IP Local Host Cannot Access Remote Host Table 7-3 TCP IP Local Host Cannot Access Remote Host Default gateway is not specified or is misconfigured on...

The Network Layer

IP is the primary Layer 3 protocol in the Internet protocol suite. In addition to internetwork routing, IP provides fragmentation and reassembly of datagrams and error reporting. Along with TCP, IP represents the heart of the Internet Protocol suite. The IP packet format is shown in Figure 7-2. The fields of the IP packet are as follows Version Indicates the version of IP currently used. IP header length (IHL)---Indicates the datagram header length in 32-bit words. Type-of-service Specifies how...

The Vlan Director Switch Management Application

The VlanDirector switch management application simplifies VLAN port assignment and offers other management capabilities for VLANs. VlanDirector offers the following features for network administrators Accurate representation of the physical network for VLAN design and configuration -verification Capability to obtain VLAN configuration information on a specific device or link interface Discrepancy reports on conflicting configurations Ability to troubleshoot and identify individual device...

Troubleshooting DECnet

This section presents protocol-related troubleshooting information for DECnet Phase IV connectivity and performance problems. The procedures outlined apply only to environments in which DECnet routing is enabled on the router, not to environments in which DECnet is being bridged (that is, bridging is enabled on the router interfaces and EtherType 6003 is being passed). This chapter does not discuss other Digital protocols, such as Maintenance Operation Protocol (MOP), local-area transport...

Troubleshooting Fiber Distributed Data Interface

FDDI Specifications Physical Connections Traffic Types Fault-Tolerant Features Frame Format CDDI Syntax Description Command Mode Usage Guidelines Sample Displays Troubleshooting Fiber Distributed Data Interface The Fiber Distributed Data Interface (FDDI) standard was produced by the ANSI X3T9.5 standards committee in the mid-1980s. During this period, high-speed engineering workstations were beginning to tax the capabilities of existing local-area networks (LANs)---primarily Ethernet and Token...

Tuning System Buffers

There are two general buffer types on Cisco routers hardware buffers and system buffers. Only the system buffers are directly configurable by system administrators. The hardware buffers are specifically used as the receive and transmit buffers associated with each interface and (in the absence of any special configuration) are dynamically managed by the system software itself. The system buffers are associated with the main system memory and are allocated to different-size memory blocks. A...

Using the show controllers Command

The show controllers exec command is another important diagnostic tool when troubleshooting serial lines. The command syntax varies depending on platform For serial interfaces on Cisco 7000 series routers, use the show controllers cbus exec command For Cisco access products, use the show controllers exec command For the AGS, CGS, and MGS, use the show controllers mci exec command Figure 15-2 shows the output from the show controllers cbus exec command. This command is used on Cisco 7000 series...

VINES Clients Cannot Communicate with Servers over Router

Symptom Clients cannot connect to VINES servers over one or more routers. Clients might or might not be able to connect to servers on their directly connected networks. Table 13-1 outlines the problems that might cause this symptom and describes solutions to those problems. Table 13-1 VINES Clients Cannot Communicate with Servers over Router Table 13-1 VINES Clients Cannot Communicate with Servers over Router Step 1 Use the show interfaces exec command to check the status of the router...

Xns Xns Broadcast Packets Not Forwarded by Router

Symptom XNS servers do not respond to broadcast requests from clients. Table 14-2 outlines the problems that might cause this symptom and describes solutions to those problems. Table 14-2 XNS XNS Broadcast Packets Not Forwarded by Router Table 14-2 XNS XNS Broadcast Packets Not Forwarded by Router Caution Because debugging output is assigned high priority in the CPU process, it can render the system unusable. For this reason, use debug commands only to troubleshoot specific problems or during...

CSU and DSU Loopback Tests

If the output of the show interfaces serial exec command indicates that the serial line is up but the line protocol is down, use the CSU DSU loopback tests to determine the source of the problem. Perform the local loop test first, and then the remote test. Figure 15-9 illustrates the basic topology of the CSU DSU local and remote loopback tests. Figure 15-9 CSU DSU Local and Remote Loopback Tests Figure 15-9 CSU DSU Local and Remote Loopback Tests Note These tests are generic in nature and...

Show interfaces fddi

To display information about the FDDI interface, use the show interfaces fddi exec -command show interfaces fddi number accounting show interfaces fddi slot port accounting (Cisco 7000 series and Cisco 7200 series) show interfaces fddi slot port-adapter port accounting (Cisco 7500 series routers) number---Port number on the selected interface. accounting---(Optional) Displays the number of packets of each protocol type that have been sent through the interface. slot---Refers to the appropriate...

Serial Lines show interfaces serial Status Line Conditions

Show Dialpeer Status Command

You can identify five possible problem states in the interface status line of the show interfaces serial display (see Figure 15-1) Serial x is down, line protocol is down Serial x is up, line protocol is down Serial x is up, line protocol is up (looped) Serial x is up, line protocol is down (disabled) Serial x is administratively down, line protocol is down Figure 15-1 Output of the HDLC show interface serial Command Table 15-1 shows the interface status conditions, possible problems associated...

Apple Talk Configuration and Troubleshooting Tips

This section offers configuration and troubleshooting tips that can help you prevent or more easily repair problems in AppleTalk internetworks. It consists of information on preventing AppleTalk problems, preventing internetwork reconfiguration problems, changing zone names, using AppleTalk Discovery Mode, and forcing an interface up to allow a router to start functioning if the network is misconfigured. Table 9-1 lists suggestions to help you avoid problems when configuring a router for...

Translational Bridging Client Cannot Connect to Server

Symptom Clients cannot communicate over a router configured as a translational bridge. Note In certain situations, replacing existing translational bridges with Cisco translational bridges can cause interoperability problems. Some translational bridge implementations map functional addresses between media (such as local-area transport LAT functional address 0900.2B00.00FA on Ethernet) to a broadcast address on the Token Ring side (such as C000.FFFF.FFFF). Cisco does not support this...

OSPF Routes Missing from Routing Table

Symptom OSPF routes and networks are not being advertised to other routers. Routers in one area are not receiving routing information for other areas. Some hosts cannot communicate with hosts in other areas, and routing table information is incomplete. Table 7-12 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-12 OSPF Routes Missing from Routing Table Table 7-12 OSPF Routes Missing from Routing Table Follow the procedures outlined in the...

IPX Enhanced Igrp Sap Updates Not Propagated by Router

Symptom Novell SAP packets are not forwarded through a router running IPX Enhanced IGRP. Clients might be unable to connect to servers over one or more routers, or they might connect only intermittently. Note Procedures for troubleshooting IPX Enhanced IGRP problems not specific to SAPs are described in the section IPX Enhanced IGRP No Connectivity over IPX Enhanced IGRP Router earlier in this chapter. Table 8-10 outlines the problems that might cause this symptom and describes solutions to...

Clocking Problem Solutions

Table 15-8 outlines suggested remedies for clocking problems, based on the source of the problem. Table 15-8 Serial Lines Clocking Problems and Solutions Table 15-8 Serial Lines Clocking Problems and Solutions Step 1 Determine whether the CSUs at both ends agree on the clock source (local or line). Step 2 If the CSUs do not agree, configure them so that they do (usually the line is the source). Step 3 Check the LBO1 setting on the CSU to ensure that the impedance matches that of the physical...

Show interfaces serial

To display information about a serial interface, use the show interfaces serial privileged exec command show interfaces serial number accounting show interfaces serial number channel-group accounting (Cisco 4000 series) show interfaces serial slot port channel-group accounting (Cisco 7500 series) show interfaces serial type slot port-adapter port serial (ports on VIP cards in the Cisco 7500 series) show interfaces serial type slot port-adapter port t1-channel accounting crb (CT3IP in Cisco 7500...

HSRP Hosts Cannot Reach Remote Networks

Symptom Hosts cannot reach hosts on remote networks. Routers in the network are running HSRP. Table 7-18 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-18 HSRP Hosts Cannot Reach Remote Networks Table 7-18 HSRP Hosts Cannot Reach Remote Networks Default gateway is not specified or is incorrectly specified on local or remote hosts Step 1 Determine whether local and remote hosts have a default gateway specification. Use the following UNIX...

Ipx Rip No Connectivity over Ipx Rip Router

Symptom IPX RIP routers are blocking connections. Clients cannot connect to servers over one or more routers running IPX RIP. Note Procedures for troubleshooting connectivity problems not specific to IPX RIP routing are described in the section Novell IPX Client Cannot Connect to Server on Remote LAN earlier in this chapter. Table 8-6 outlines the problems that might cause this symptom and describes solutions to those problems. Table 8-6 IPX RIP No Connectivity over IPX RIP Router Table 8-6 IPX...

SDLC Intermittent Connectivity

Symptom User connections to hosts time out over a router configured to perform SDLC transport. Table 10-10 outlines the problem that might cause this symptom and describes solutions to that problem. Table 10-10 SDLC Intermittent Connectivity Table 10-10 SDLC Intermittent Connectivity Step 1 Place a serial analyzer on the serial line attached to the source station and monitor packets. Step 2 If duplicate packets appear, check the router configuration using the show running-config privileged exec...

SDLC Client Cannot Connect to Host over Router Running SDLLC

Symptom Users cannot open connections to hosts on the other side of a router configured to support SDLC Logical Link Control (SDLLC). Table 10-11 outlines the problems that might cause this symptom and describes solutions to those problems. Table 10-11 SDLC Client Cannot Connect to Host over Router Running SDLLC Table 10-11 SDLC Client Cannot Connect to Host over Router Running SDLLC SDLC physical or data link-layer problem Step 1 Use the show interface slot port exec command to check the state...

Network Analyzers

A network analyzer (also called a protocol analyzer) decodes the various protocol layers in a recorded frame and presents them as readable abbreviations or summaries, detailing which layer is involved (physical, data link, and so forth) and what function each byte or byte content serves. Most network analyzers can perform many of the following functions Filter traffic that meets certain criteria so that, for example, all traffic to and from a particular device can be captured Present protocol...

Ipx Rip Sap Updates Not Propagated by Router

Symptom Novell SAP packets are not forwarded through a router running IPX RIP. Clients might be unable to connect to servers over one or more routers, or they might intermittently be able to connect. Note Procedures for troubleshooting IPX RIP problems not specific to SAPs are described in the section IPX RIP No Connectivity over IPX RIP (12 of 30) 11 30 2000 11 15 42 PM Router earlier in this chapter. Additional problems relating to intermittent connectivity problems are described in the...

XNS Clients Cannot Connect to Servers over Router

Symptom Clients cannot make connections to XNS servers across a router. Clients might be able to connect to servers on their directly connected networks. Table 14-1 outlines the problems that might cause this symptom and describes solutions to those problems. Table 14-1 XNS Clients Cannot Connect to Servers over Router Table 14-1 XNS Clients Cannot Connect to Servers over Router Step 1 Use the show interfaces exec command to check the status of the router interfaces. Step 2 If the status line...

IP Enhanced IGRP Routes Missing from Routing Table

Symptom Routes are missing from the routing table of routers running Enhanced IGRP. Hosts on one network cannot access hosts on a different network. Hosts on the same network might or might not be able to communicate. The problem might occur in internetworks running only Enhanced IGRP or in an internetwork running Enhanced IGRP and another routing protocol. Table 7-14 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-14 IP Enhanced IGRP...

TCPIP Routes Learned from the Wrong Interface or Protocol

Symptom Routes in the routing table were learned from the wrong interface or protocol. For example, networks that should be reached through one interface are shown in the routing table to be reachable through another interface instead. This problem occurs only in a multiprotocol environment (see the section 'Split Horizon Example, later in this chapter). Table 7-4 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-4 TCP IP Routes Learned from...

Novell SAPs

The list of Novell SAPs in Table 8-14 is unverified information contributed from various sources. Novell, in an official capacity, does not and has not provided any of this information. Table 8-14 Novell SAPs, Their Descriptions, and Their Decimal and Hex Values Table 8-14 Novell SAPs, Their Descriptions, and Their Decimal and Hex Values NACS Async Gateway or Asynchronous Gateway Bridge Server or Asynchronous Bridge Server Point to Point (Eicon) X.25 Bridge Server Time Synchronization Server or...

VINES Client on Serverless Network Cannot Connect to Server over PSN

Symptom Clients on a serverless network (that is, a network segment that has no attached VINES servers) cannot open a connection to a VINES server over a PSN. Table 13-3 outlines the problems that might cause this symptom and describes solutions to those problems. Table 13-3 VINES Client on Serverless Network Cannot Connect to Server over PSN Table 13-3 VINES Client on Serverless Network Cannot Connect to Server over PSN Step 1 Use the show running-config privileged exec command to view the...

Iso Clns Technology Basics

The world of OSI networking has a unique terminology End system (ES) refers to any nonrouting network device. Intermediate system (IS) refers to a router. Area is a group of contiguous networks and attached hosts that are specified by a network administrator or manager to be an area. Domain is a collection of connected areas. Routing domains provide full connectivity to all end systems within them. Addresses in the ISO network architecture are referred to as NSAP addresses and network entity...

IPX Enhanced IGRP Router Stuck in Active Mode

Symptom An IPX Enhanced IGRP router is stuck in Active mode. The router repeatedly sends error messages similar to the following DUAL-3-SIA Route 3c.0800.0c00.4321 Stuck-in-Active Note Occasional messages of this type are not a cause for concern. This is how an Enhanced IGRP router recovers if it does not receive replies to its queries from all its neighbors. However, if these error messages occur frequently, you should investigate the problem. For a more detailed explanation of Enhanced IGRP...

Establishing a Reverse Telnet Session to a Modem

If you are running Cisco IOS Release 11.0 or earlier, you must establish a reverse Telnet session to configure a modem to communicate with a Cisco device. As long as you lock the data terminal equipment (DTE)-side speed of the modem (see Table 16-5 for information on locking the modem speed), the modem will always communicate with the access server or router at the desired speed. Be certain that the speed of the Cisco device is configured prior to issuing commands to the modem via a reverse...

Apple Talk Enhanced IGRP Router Stuck in Active Mode

Symptom An AppleTalk Enhanced IGRP router is stuck in Active mode. The router repeatedly sends error messages similar to the following to the console DUAL-3-SIA Route 2.24 Stuck-in-Active Note Occasional messages of this type are not a cause for concern. This is how an Enhanced IGRP router recovers if it does not receive replies to its queries from all its neighbors. However, if these error messages occur frequently, you should investigate the problem. For a more detailed explanation of...

Ripigrp Routes Missing from Routing Table

Symptom Routes are missing from the routing table. Hosts on one network cannot access hosts on a different network. Error messages stating host or destination unreachable are generated. The problem might be occurring in an internetwork running only RIP or IGRP, or a combination of the two. Table 7-9 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-9 RIP IGRP Routes Missing from Routing Table Table 7-9 RIP IGRP Routes Missing from Routing...

Troubleshooting Iso Clns

This section presents protocol-related troubleshooting information for ISO CLNS protocol connectivity and performance problems. It describes specific ISO CLNS symptoms, the problems that are likely to cause each symptom, and the solutions to those problems. Note Discussions of host configuration problems in this chapter assume that the host is a UNIX system. Equivalent actions might also be applicable to non-UNIX hosts, but the discussions do not specifically address non-UNIX end-station...

Adobe Acrobat Reader

In order to view the scalable Portable Document Format (PDF) versions of graphics and tables on Cisco Connection Documentation CD-ROM, you need to have Adobe Acrobat Reader configured as a helper application of Verity Mosaic. The Adobe Acrobat Reader installer is copied to the same location as the Cisco Connection Documentation CD-ROM applications on the Macintosh, Windows, SunOS, and Solaris platforms when you install Cisco Connection Documentation CD-ROM. Run the Adobe Acrobat Reader...

TCPIP Problems Forwarding BOOTP and Other UDP Broadcasts

Symptom Problems occur when forwarding BOOTP or other UDP broadcast packets. UDP broadcasts sent from network hosts are not forwarded by routers. Diskless workstations cannot boot. Table 7-7 outlines the problems that might cause this symptom and describes solutions to those problems. Table 7-7 TCP IP Problems Forwarding BOOTP and Other UDP Broadcasts Figure 7-12 A Misconfigured Access List Sample Network Missing or misconfigured ip helper-address Step 1 Use the debug ip udp privileged exec...