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You can search known software bugs with the Software Bug Toolkit. When a layer 3 interface is connected to a layer 2 switchport, it is not able to interpret these frames, which results in Input errors, WrongEncap errors, and Input queue drops. << The WS-X4448-GB-RJ45, WS-X4548-GB-RJ45, and WS-X4548-GB-RJ45V switching modules have 48 oversubscribed ports in six groups of eight ports each: The eight ports within each group use common circuitry that effectively multiplexes the group into a single, non-block, full-duplex Gigabit Ethernet connection to the internal switch fabric. For more information on troubleshoot hardware related errors on Catalyst switches, see the Hardware Problems section of this document. << Description:show interfacescounter indicates that the transmit jabber timer expired. >> 2023 Cisco and/or its affiliates. The software version is also a factor. Verify the cable selection. Thanks for this! Description:The number of times the receiver hardware was unable to hand received data to a hardware buffer.Common Cause:The input rate of traffic exceeded the ability of the receiver to handle the data. Small amounts of symbol errors can be ignored. To open a Telnet session to another device on the network from the switch, perform this task in privileged mode: This example shows how to open a Telnet session from the switch to the remote host labsparc: The login timer is the number of minutes after which an idle session is disconnected. The total number of frames which are filtered because of the type of VLAN information contained in the frame. A Symbol error means the interface detects an undefined (invalid) Symbol received. For example, the Catalyst 1900/2820 turns ports orange when they are in STP block mode. No destination broadcast are the number of broadcast packets that the port did not forward to any other ports. The number of times the carrier was not present in the transmission.Common Causes:Check for a bad cable. This is because the output queue on that interface is overwhelmed by the excess traffic due to the speed mismatch between the inbound and outbound bandwidths. When the size of the IP input queue is between the minimum and maximum thresholds, normal IP packets are dropped based on a certain drop probability. 24 0 obj In order to resolve this issue, create trunk ports instead of sub interfaces. For example, if you have two routers connected and you disable CDP on one router interface, this results in unknown protocol drops on that interface. Theshow counters interfacecommand was introduced in software version 12.1(13)E for the Catalyst 6000 series only anddisplays 32-bit and 64-bit error counters. Most switches have some way to track the packets and errors that occur on a port or interface. Share Improve this answer Follow answered May 19, 2016 at 14:08 Ron Maupin 97.5k 26 112 188 /Parent 3 0 R The total number of frames whose first transmission attempt was delayed, due to traffic on the network media. To display the MAC address for a specific port, perform this task in privileged mode: Display the MAC address for a specific port. by CDP is useful to detect errors, as well as port and system statistics on nearby Cisco devices. For example, you can look attheMessages and Recovery Proceduresfor Cisco IOS Releases. The Canonical Format Indicator (CFI) bit in the TCI of an 802.1q frame is is set to 0 for the ethernet canonical frame format. Cisco ethernet interfaces are normally down / down if they don't have a link. If an egress interface is over-subscribed, it is normal to see output buffer failures that increment along with Out-Discards. >> This can happen where you have multiple high-speed ports flowing to a single (usually slower) port. The number of times a collision occurred before the interface transmitted a frame to the media successfully.Common Causes:Collisions are normal for interfaces configured as half-duplex but must not be seen on full duplex interfaces. /First 12 0 R endobj Note: For Catalyst 3750, 3550, 2970 , 2950/2955, and 2900/3500XL Series switches use theshow postcommand, which indicates a simple pass or fail for the hw status. The excessive collisions counter increases after 16 consecutive late collisions have occurred in a row. The designated port transmits BPDUs, and the non-designated port receives BPDUs. /Parent 5 0 R Use these resources to familiarize yourself with the community: Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. /N 28 0 R Fa0/1 connected 1 a-full a-100 10/100BaseTX . Gigabit Ethernet (1000 Base-X) uses 8B/10B Encoding to translate 8bit data from the MAC sublayer(layer 2) to a 10bit Symbol to send over the wire. Run a port TDR to test the integrity of the copper cable. Check the IP address, subnet mask, default gateway, dynamic routing protocol configuration, static routes, and so on. The same output show up for trunk ports as well as access ports. Frames received that exceed the maximum IEEE 802.3 frame size (1518 bytes for non-jumbo Ethernet) and have a bad Frame Check Sequence (FCS). /Rect [162 456.8999938965 320.8200073242 468.1199951172] To use this feature, you must install the application on the client accessing the switch and you must configure SSH the switch. 26 0 obj Without the loop guard feature, the port assumes the designated port role. (Line down/up), Layer 2 goes down and then up. Check the results ofshow modulefor Catalyst 6000 and 4000 series switches that run Cisco IOS. /V 58 0 R The only way to clear the bit counters in these switches is to reload. uuid:af7b7cc0-33fd-4b39-afce-898b51ab9cfc Swap the GBIC (if removable) for fiber connections. /Border [0 0 0] The mode-conditioning patch cord prevents the over use of the receiver for short lengths of MMF and reduces differential mode delay for long lengths of MMF. /concept () The traffic load on the interface is excessive and causes the frames to be discarded. Description:show interfacesandshow interfaces counters errors. /Type /Metadata This example of the show interface command shows theLast input neveron the TenGigabitEthernet1/15 interface. Description:show interfaces counters errors. 04:20 PM. You must either enable or disable link negotiation on both ends of the link. >> The two devices that cause the late collision never see that each sends until after it puts the entire packet on the network. Congestion can lead to packet loss. The total number of frames received whose length exceeds the System MTU, yet which have good FCS values. Refer to these documents for more information on the different trunking modes, guidelines, and restrictions: System Requirements to Implement Trunking. Description:show interfacescounter. A key size with a larger number provides higher security but takes longer to generate. show tech-support port-channel. Dispersion-shifted single-mode fiber-optic cable. If the transmitted traffic MTU exceeds the supported MTU the switch does not forward the packet. Changes aresavedto the config in Cisco IOS with the write memory command. You must enable CDP on all of the Catalyst 4000 family, Catalyst 5000 family, and Catalyst 6500 series switches in the network. For example, a runt, giant, or an FCS-Err does not increment the rcv-err counter. 06:17 PM The next two sections describe how to use IP traceroute. Before you can open a Telnet session to the switch, you must first set the IP address (and in some cases the default gateway) for the switch. The counter also increments when the destination address of the packet is learned on the port that the packet was received on. application/pdf Each time we previously disconnected and reconnected the cable the port status just remained down/down. The port starts to drop the packets when the Tx buffer is full and thus increases the underruns and the output buffer failure counters. Normally you can identify this situation if the port has many packet errors, or the port constantly flaps (loses and regains link). Description:show interfaces. There are no specific requirements for this document. The line protocol up message shows the data link layer status of the interface and says that the interface can send and receive keepalives. endobj Platform Exceptions:Catalyst Cat4000 Series that run Cisco IOSPrevious to software Version 12.1(19)EW, the giants counter incremented for a frame > 1518bytes. Description:show interfaces counters errors. When a frame is received which contains an 802.1Q tag the frame is filtered and this statistic is incremented. Last input nevermeans there was no successful interface packet transfer to other end point or terminal. If either device has multiple Gigabit ports, connect the ports to each other. 20 0 obj The command udld aggressive-mode can be configured on switches that run Cisco IOS (check release notes for command availability) for point-to-point connections between switches where unidirectional links cannot be tolerated. Refer to Mode-Conditioning Patch Cord Installation Note for more information. When the Gigabit Ethernet switching module is not fully utilized, you can balancee the port connections across port groupings to maximize available bandwidth. 14 0 obj endobj If the segment is shared, other devices on this segment can transmit so much that the switch has no opportunity to transmit. endobj Common Causes:Excessive collisions are typically an indication that the load on the segment needs to be split across multiple segments but can also point to a duplex mismatch with the attached device. To apply configuration commands to a particular port, you must specify the appropriate logical module. /Border [0 0 0] sh ip protocols - all of the dynamic routing If single connection or Step 3 fails with SC connectors, loop the port back to itself (port one RX goes to port one TX). This is not available on all IOS versions. /Subtype /Link This example shows how to disconnect an active console port session and an active Telnet session: The next two sections describe how to use IP ping. /Border [0 0 0] Description:show interfaces counters errors. This shows the number of hours, minutes, and seconds since the last packet was successfully received by an interface and processed locally on the router. In some cases, these delays can be up to 50 seconds. This only happens under extreme, high stress conditions. 06-22-2009 Use theinterface-rangecommand to do this on multiple interfaces at once. Upgrade the NIC card driver to the latest version available on the web site of the manufacture to resolve this. A cable can be just good enough to connect at the physical layer, but it corrupts packets as a result of subtle damage to the wiring or connectors. Description:show interfaces counters errors. 15 0 obj You can use this utility from a switch that is not in the Layer 2 path between the source and the destination; however, all of the switches in the path, including the source and destination, must be reachable from the switch. i feel this command is only for trunks using DTP and not for access ports. You can remove some devices from crowded segments to other less populated segments. /F 27 0 R It also occurs when the hardware hits an oversubscription. Theshow interfacescard-type {slot/port}counterscommand is used when you run Cisco IOS on the Supervisor. For further information on how to troubleshoot hardware problems on Catalyst switches that run Cisco IOS, navigate to the Cisco Switchessupport pages, choose your platform and look at the Troubleshooting > Hardwaresection. WK:w9\lBdOeX>V!RKB.GUMrx8<3pfs,nNX`IVw=OYGe; L2]>[1aUGYv4(}d({PJRiPh@fHK49]a9l&]+X.H bVFO4 i8qQf3 This example shows the output of the show users command when local authentication is enabled for console and Telnet sessions (the asterisk [*] indicates the current session): This example shows the output of the show users command when TACACS+ authentication is enabled for console and Telnet sessions: This example shows how to display information about user sessions using the noalias keyword to display the IP addresses of connected hosts: To disconnect an active user session, perform this task in privileged mode: Disconnect an active user session on the switch. 2011-03-17T11:53:32Z These are brief descriptions of when the No dest, (unicast, multicast, and broadcast) counters can increment: If a port is an access port, and the port is connected to an Inter-Switch Link Protocol (ISL) trunk port, the No dest counter is very large since all inbound ISL packets are not forwarded. The show interfaces status cli command shows you all interfaces. This is helpful to diagnose a hardware problem on a module or port. %PDF-1.4 When you use either the WS-X6548-GE-TX or WS-X6148-GE-TX modules, there is a possibility that individual port utilization can lead to connectivity problems or packet loss on the surrounding interfaces. This means that the port is up as far as Layer 1 (L1) is concerned. Once you know the switch actually has the MAC address of the device in the CAM table, determine whether this device is on the same or different VLAN from where you try to ping. Description:show interfacescounter. 3 0 obj If either device does not support Gigabit auto-negotiation, disable the Gigabit auto-negotiation, and it forces the link up. Multiple splices and substandard fiber-optic cable reduce the cable distances. The reason for this occurrence is because the time to propagate the signal from one end of the network to another is longer than the time to put the entire packet on the network. /Dest (G1020163) If you have a large amount of alignment errors, FCS errors, or late collisions, this can indicate one of these: A common issue with speed/duplex is when the duplex setup are mismatched between two switches, between a switch and a router or between the switch and a workstation or server. Refer to theCatalyst Switch Cable Guide. As the half-duplex side transmits, the full duplex side does not wait its turn and transmits simultaneously which causes a late collision. 29 0 obj The interface displays a lot of information including a visual representation of each port's status. Avoid daisy-chained hubs whenever possible. Destination unreachableIf the default gateway cannot reach the specified network, a destination unreachable message is returned. If that VLAN is deleted, then the port or interface becomes inactive. /Dest (G1029178) /Filter /FlateDecode Swap suspect GBIC with known good GBIC. New here? Swap suspect cable with known good cable. This chapter includes the following major sections: Checking Module Status, page 6-2 Checking Interfaces Status, page 6-2 Displaying MAC Addresses, page 6-3 Checking Cable Status Using TDR, page 6-3 Using Telnet, page 6-5 This is useful to know when a dead interface has failed. The | include connected shows only the lines of the output that contain the word "connected". The input rate of traffic exceeded the ability of the receiver to handle the data. The STP loop guard feature provides additional protection against Layer 2 forwarding loops (STP loops). Bypass the media convertor if possible to rule it out. It is this configuration that is loaded into memory when the device is first booted. endstream A port remembers what VLAN it is assigned to, even if the VLAN itself is deleted. Note: On the Catalyst 4503, 4506, and 4507R series switches, this capability is automatically enabled. This document covers reasons that STP can fail, what information to look for to identify the source of the problem, and what kind of design minimizes STP risks. Thus, Rx-No-Pkt-Buff on each port can be counted when the total traffic rate of this ASIC port group exceeds 1 Gbps, since WS-X4548-GB-RJ45 is 8:1 oversubscribed module. Refer toUnderstanding and Configuring VLAN Trunk Protocol (VTP)for more information on VTP. The common commands used to find this type of information are described in the Most Common Port and Interface Troubleshooting Commands for Cisco IOS section of this document. For example, here you see a high amount of output drops on the interface GigabitEthernet 8/9 on a Catalyst 6500 Series Switch: In order to analyze the problem, collect the output of these commands: show platform hardware capacity rewrite-engine drop. Port status as seen in the color assist mode. 7 0 obj The Catalyst 6000/4000 does not turn the port light orange when it blocks for STP. Note If you are using Kerberos to authenticate to the switch, you will not be able to use the secure shell encryption feature. Note:The Catalyst 6500/6000 series switches do not clear the bit counters of an interface with theclear counterscommand. the NIC cards in your machines going to sleep because of inactivity. Jumbos have larger frame sizes, typically > 9000 bytes.