In addition, you can use Telnet from the switch to access other devices in the network. Use theshow interfaces fastEthernet 6/1 statuscommand to display this: Last input, output - The number of hours, minutes, and seconds since the last packet was successfully received or transmitted by the interface. Trunking changes the formatting of the packet. Undersize = frame < 64bytes. /concept () The bottom line is that even if you configure the interface to recover from errdisable the problem reoccurs until the root cause is determined. << >> This can lead to slow throughput of packets across the device. A link light does not guarantee that the cable is fully functional. /Last 12 0 R Common Causes:This is usually the result of collisions or a physical problem (such as cabling, bad port or NIC) but can also indicate a duplex mismatch. /Subtype /XML Interface resets can occur along with the underruns. Eliminate faulty media convertors: fiber-to-copper, and so on. >> For a single interface.Cisco-Switch#show int g1/0/7 Last input never, output 1y25w, output hang never, For all interfaces.Cisco-Switch#show int | in Last | proto, I think this command will give u the uptime of that interface. For fiber, make sure you have the correct cable for the distances involved and the type of fiber ports that are used. Wheb ports or interlaces are shut down as a result of errdisable are referred to as causes in Cisco IOS. /Author (ctsadmin-p.gen) To monitor inbound and outbound traffic on the port as displayed by the next output, for unicast, multicast, and broadcast traffic. In its operation, STP relies on continuous reception or transmission of BPDUs based on the port role. Specify a particular module number to see information on the ports on that module only. Try the cable in another port or interface if one is available and see if the problem continues. Verify device A and B use the same GBIC, short wavelength (SX), long wavelength (LX), long haul (LH), extended wavelength (ZX), or copper UTP (TX). Because of this, a chance exists for the device connected to the catalyst switch to drop packets. Command: show startup-configuration Description: This command is the same as the above show running-configuration command except this will output the configuration that is stored in NVRAM. The size of this buffer is only 16 KB. It is caused by protocols that are not understood by the router/switch. 5 0 obj 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 flushes counter can be used but never increments on the Catalyst 4000 Series that run Cisco IOS.) If the mismatch occurs between two Cisco devices with the Cisco Discovery Protocol (CDP) enabled, you see the CDP error messages on the console or in the logging buffer of both devices. For example, if a large amount of traffic bursts comes in on a gigabit interface and is switched out to a 100Mbps interface, this can cause Xmit-Err to increment on the 100Mbps interface. This usually happens because one of the ports of a physically redundant topology (not necessarily the STP block port) no longer receives STP BPDUs. You can use IP ping to test connectivity to remote hosts. There are other causes for late collisions besides duplex mismatch, but this is one of the most common reasons. Category 3 copper cable can be used for 10 Mbps unshielded twisted pair (UTP) connections but must never be used for 10/100 or 10/100/1000Mbps UTP connections. Fast aging temporarily sets the CAM aging time to the number of seconds that the user specifies, and is used in conjunction with the Topology Change Notification (TCN) process. Note: There is, an Out-Discard counter in the Cisco IOSshow interfaces counters errorscommand which is explained inTable 1. /keywords () 8 0 obj Switches can participate as the source or destination of the traceroute command but will not appear as a hop in the traceroute command output. All switches in the path must be reachable from each other. endobj If single connection or Step 3 fails with SC connectors, loop the port back to itself (port one RX goes to port one TX). endobj But the problem is that this OID returns "1:up" as soon as a cable is plugged into the port and does not reflect the different status the port might have including: Blinking green: Link has activity Solid amber: Port is faulty etc, Any clue or hint on which OIDs I should use? To determine when a datagram reaches its destination, traceroute sets the UDP destination port in the datagram to a very large value that the destination host is unlikely to be using. This is an indication of a bad frame generated by the connected device. 18 0 obj The default CAM aging time is five minutes, which means that the switch flushes the table of learned MAC addresses every five minutes. Enter both the module number and the port number to see detailed information about the specified port. Total output drops - The number of packets dropped because the output queue is full. Note: For fiber connections, make sure the transmit lead of one port is connected to the receive lead of the other port. The first up refers to the physical layer status of the interface. /Annots [16 0 R 17 0 R 18 0 R 19 0 R 20 0 R 21 0 R 22 0 R 23 0 R 24 0 R 25 0 R /I 31 0 R Cisco IOS has the option to use theglobal spanning-tree portfast defaultcommand to automatically apply portfast to any interface configured as a layer 2 access switchport. TCNs and fast aging are fairly rare. Changes aresavedto the config in Cisco IOS with the write memory command. << Check the results of the POST results from the switch to see if there were any failures indicated for any part of the switch. Problems sometimes occur between Cisco switches and certain third-party NIC cards. 04:30 PM << Giant frames are defined as any frame over the maximum size of an ethernet frame (larger than 1518 bytes) that has a bad FCS. If this does not solve the issue, you need to consider a module without any oversubscription of ports. 09-26-2014 i see. The packet is then dropped. Find answers to your questions by entering keywords or phrases in the Search bar above. /Count 4 Each time we previously disconnected and reconnected the cable the port status just remained down/down. This happens when new hardware comes out and requires special support from the software. Impossible to tell. 14 0 obj Description:show interfacescounter. /ModDate (D:20110317115332Z) It is common for devices like laptops or other devices to be set to autonegotiate as well, yet sometimes autonegotation issues occur. Port status : Secure down help TechExams Community Theshow interfaces counters errorscommand is used in Cisco IOS to display the output of the interface errors only. The number of frames dropped on an interface because the CFI bit is set. >> To display the active user sessions on the switch, perform this task in privileged mode: Display the currently active user sessions on the switch. It also occurs when the hardware hits an oversubscription. 2011-03-17T11:53:32Z /Type /Annot /Count 23 Release Notes for the Cisco Catalyst IR1101 Rugged Series Router << These messages generally tell you what the mismatch is and where it occurs. Cisco Internetwork Operating System Software . endobj /Dest (G1019941) There can be a situation where the software is not compatible with the hardware. 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. Use theshow run interfacecommand and check to see if the interface is in ashutdownstate: If the port goes into shutdown mode immediately after a reboot of the switch, the probable cause is the port security setup. Without attenuators, the minimum link distance is 24.9 miles (40 km). ". /Type /Pages This traffic level constrain is due to hardware limitation. Use theshow interfacecommand for Cisco IOS to look for errdisable, disable or shutdown status. Check the physical connection on both sides. All of these protocols can be disabled for access ports where they are not needed, so the switch port or interface starts forwarding packets a few seconds after it establishes a link with its neighbor device. Description:show interfacescounter. This utility determines the path by looking at the forwarding engine tables of the switches in the path. Share What can cause "FastEthernet is up, line protocol is down" on a Cisco Refer toUnderstanding and Configuring VLAN Trunk Protocol (VTP)for more information on VTP. 3506 Check the IP address, subnet mask, default gateway, dynamic routing protocol configuration, static routes, and so on. Hi Nima, "show ip interface" command would show you the L1 and L2 status of the interface, instead "show port-security interface" would show you the status of the port security, now if you enable port security on an interface where there is a host connected the port status would be in "Secure-up", but if there is nothing connected to that interface, then the port status would be "Secure-down . In order to resolve this, change the mode of the switch port tostatic accessortrunkas per your requirement. You can trace a Layer 2 path by specifying the source and destination IP addresses (or IP aliases) or the MAC addresses. ), how to connect the different cables, and which cables are used by most Cisco switches and modules, refer to Catalyst Switch Cable Guide . Note:Some port LEDs of the platform work differently in regard to STP. /Subtype /Link This can be an indication of faulty hardware, dot1q or ISL trunking configuration issues. The flushes counter in the show interface command output increments as part of selective packet discard (SPD), which implements a selective packet drop policy on the IP process queue of the router. An excessive collision happens when a packet has a collision 16 times in a row. Port status up and down and up again - Cisco If your network is live, ensure that you understand the potential impact of any command. If the frames received on any group exceeds the bandwidth of 1 Gbps, the device starts to drop the frames. << Note: If the output of theshow interface switchportcommand displays the port as a trunk port even after you configure the port as an access port with theswitchport access vlancommand, issue theswitchport mode accesscommand in order to make the port an access port. Excessive errors for certain counters usually indicate a problem. - last edited on By default, software processes inside the switch can shut down a port or interface if certain errors are detected. . The loop guard feature makes additional checks. If that VLAN is deleted, then the port or interface becomes inactive. >> Last input nevermeans there was no successful interface packet transfer to other end point or terminal. If you have physical access to the switch, it can save time to look at the port LEDs which give you the link status or can indicate an error condition (if red or orange). Large amounts of symbol errors can indicate a bad device, cable, or hardware. After 12.1(19)EW, a giant inshow interfacesincrements only when a frame is received >1518bytes with a bad FCS. For each port on the switch, the command provides a real-time display of the rate at which data is received (Rx) and transmitted (Tx) in terms of kilobits per second (KBits/s), number of packets per second (Pkts/s), and utilization (Util) expressed as a percentage of the total bandwidth available. InCisco IOS software you have the ability to automatically re-enable a port after a configurable amount of time spent in the errdisable state. i feel this command is only for trunks using DTP and not for access ports. To use this feature, you must install the application on the client accessing the switch and you must configure SSH the switch. As the half-duplex side transmits, the full duplex side does not wait its turn and transmits simultaneously which causes a late collision. Runt frames or frames received that are less than 64 bytes (which includes the FCS bits and excludes the frame header) and have either an FCS error or an alignment error. The total number of frames which are filtered because of the type of VLAN information contained in the frame. In the example, under the show interfaces FastEthernet0/1 command, look at a line that shows something such as: Last input 00:00:41, output 00:00:00, output hang never. 3 0 obj 7 0 obj The runt counter only incremented when a frame less than 64 bytes was received. /Type /Annot 15 0 obj 6 0 obj When a port is in error-disabled state, it is effectively shut down and no traffic is sent or received on that port. The bytes counter includes both the data and MAC encapsulation in the error free packets received and transmitted by the system. There are no specific requirements for this document. The traffic load on the interface is excessive and causes the frames to be discarded. New here? Port Status : Secure-down. Normally the deferred frames are the number of frames that have been transmitted successfully after waiting for the media, because the media was busy. /Border [0 0 0] /CreationDate (D:19990615140519Z) The number of valid size frames with Frame Check Sequence (FCS) errors but no frame errors. If the end device is on a different VLAN from where you try to ping, a L3 switch or router must be configured to allow the devices to communicate. For this reason, they were discarded by the switch. Rule out any bad patch panel connections or media convertors between source and destination. This is because the output buffer of the interface is overwhelmed by the excess traffic due to the speed mismatch between the inbound and outbound bandwidths. Ifshow interfacesshows up/ line protocol up (connected) but you see errors increment in the output of either command, refer to the Common Port and Interface Problems section of this document for advice. If the Rx still works on the queue, once the interval time expires, the Tx sends a new pause frame again with a new interval value. >> Share Improve this question Follow asked Aug 23, 2015 at 6:13 ae41 >> Traceroute starts by sending a User Datagram Protocol (UDP) datagram to the destination host with the TTL field set to 1. Alignment errors are the result of collisions at half-duplex, a duplex mismatch, bad hardware (NIC, cable, or port), or connected devices that generate frames that do not end with an octet and have a bad FCS. << >> SecureStatic Address Aging : Disabled. The Cisco Catalyst IR1101 Rugged Series Router is a next generation modular industrial router which has a base module with additional Pluggable Modules that can be added. No action is required. Look at your logs (if link state logging is enabled) for signs of the interface going down/up. . << /Parent 14 0 R << The show interfaces card-type {slot/port}command is the used command for Cisco IOS on the Supervisor to display error counters and statistics. Warning: Category 5e and Category 6 cables can store high levels of static electricity because of the dielectric properties of the materials used in their construction. /Dest (G1024221) Is there a command that will show information as to how long that port has been in an "up" state? It would be counted on theshow interfaceoutput for the appropriate physical interface. Layer 1 goes down and then up. A single broken wire or one shutdown port can cause the problem where one side has a link light, but the other side does not. See the Common Port and Interface Problems section of this document for more information. By using command line(ssh), I can get switch interfaces status like belowjust demo: Cisco-Switch# show int status Port Name Status Vlan Duplex Speed Eth0/1 test_alias connected 1 a-full a-100 Eth0/2 notconnect 1 auto auto Eth0/3 connected 3 a-full a-100 Eth0/4 connected 3 a-full a-100 Eth0/5 potchann linkFlapE 255 auto auto Eth0/6 notconnect 300 auto auto Eth0/7 sfpAbsent routed auto . Use theshow interfaces statuscommand to display speed and duplex setup as well as other information. If unicast flooding is enabled on that port, it can cause the port to shut down after a reboot. When you use an LX/LH GBIC with 62.5-micron diameter MMF, you must install a mode-conditioning patch cord (CAB-GELX-625 or equivalent) between the GBIC and the MMF cable on both the transmit and receive ends of the link. /Type /Annot This only happens under stress conditions but can happen with bursts of traffic on several ports. 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. 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). R2#show inter fa 0/0. All rights reserved. /Length 13 0 R Verify the cable selection. This is because they are only detected in transmissions of packets longer than 64 bytes. Change the cable and patch panel cord to ensure that the cable and patch cords are not defective. Note For complete syntax and usage information for the commands used in this chapter, refer to the Command ReferenceCatalyst4000Family, Catalyst 2948G, and Catalyst 2980G Switches. This example shows how to check module status on a Catalyst2948G switch: This example shows how to check module status on a specific module: You can display summary or detailed information on the switch ports using the show port command. When the local engineer was unplugging the cable, checking port LEDs etc on the CN side we could see the below, so it was definitely recognising the cable being unplugged even from the switch side only. /Resources 30 0 R This is an indication that the internal send (Tx) buffer is full.Common Causes:A common cause of Xmit-Err can be traffic from a high bandwidth link that is switched to a lower bandwidth link, or traffic from multiple inbound links that are switched to a single outbound link. /Parent 5 0 R Alignment errors are a count of the number of frames received that do not end with an even number of octets and have a bad Cyclic Redundancy Check (CRC).Common Causes:These are usually the result of a duplex mismatch or a physical problem (such as cabling, a bad port, or a bad NIC). Swap the GBIC (if removable) for fiber connections. The command output displays all network layer (Layer3) devices, such as routers, that the traffic passes through on the way to the destination. cisco - interface down time summary - Network Engineering Stack Exchange Without the loop guard feature, the port assumes the designated port role. 5. 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. Bypass the patch panel if possible to rule it out. Use theshow mac address-table dynamiccommand or substitute theinterfacekeyword. In order to check to see how long the port is in, Last input 00:00:41, output 00:00:00, output hang never, Last input never, output never, output hang never. 11 0 obj Description: show interfaces and show interfaces counters errors.The number of times a collision is detected on a particular interface late in the transmission process. The interface displays a lot of information including a visual representation of each port's status. 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. For a 10 Mbit/s port this is later than 512 bit-times into the transmission of a packet. Port status as seen in the default dashboard color mode. Port or Interface Status is Disable or Shutdown Port or Interface Status is errDisable Port or Interface Status is Inactive Uplink Port or Interface Status is Inactive Deferred Counter on the Catalyst Switch Interface Increments Intermittent Failure to set timer [value] from vlan [vlan no] Trunking Mode Mismatch Jumbos, Giants, and Baby Giants Multiple splices and substandard fiber-optic cable reduce the cable distances. To identify a Layer 2 path, perform one of these tasks in privileged mode: l2trace {src-mac-addr} {dest-mac-addr} [vlan] [detail]. The collision frames counters are the number of times a packet was attempted to be transmitted but was not successful but was successful on its next attempt. The cable can have encountered physical stress that causes it to be functional at a marginal level. The interfaces that are "up" are in the connected state. A switch is in down state when there is nothing connected to the port or if its admin shutdown. For the Cisco IOS system messages format, you can refer to theMessages and Recovery Procedures Guidefor the release of software you run. . Find answers to your questions by entering keywords or phrases in the Search bar above. - edited 1 0 obj /Count 10 Verify that the connected device operates correctly. Giant frames or 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). This issue is resolved in Cisco IOS release 12.1(19)EA1 or 12.2(18)SE or later. For troubleshoot information, see theDeferred Frames (Out-Lost or Out-Discard)section of this document. 11:42 AM The excessive collisions counter increases after 16 consecutive late collisions have occurred in a row. After you issue the command, re-boot the switch or else the output of theshow interface status modulecommand shows the uplink port as inactive. Interface up/down: why? - Cisco The sum of all errors that prevented the final transmission of datagrams out of the interface.Common Cause:This issue is due to the low Output Queue size. ciscomoderator. The number of failed buffers and the number of buffers swapped out.Common Causes:A port buffers the packets to the Tx buffer when the rate of traffic switched to the port is high and it cannot handle the amount of traffic. Using Secure Shell Encryption for Telnet Sessions. Number of packets received by the port from the network, where the packets were more than 1514 bytes. Check the results ofshow modulefor Catalyst 6000 and 4000 series switches that run Cisco IOS. Switch#show inter status. Port Name Status Vlan Duplex Speed Type . For example, with the WS-X4448-GB-RJ45 10/100/1000 switching module, you can connect ports from different groups, such as ports 4, 12, 20, or 30 (in any order), before you connect ports from the same group, such as ports 1, 2, 3, 4, 5, 6, 7, and 8. Set the duplex to full-duplex. Basically, up/down means the port is available for a cable/connection, but doesn't have one. A common cause is traffic from a high bandwidth link that is switched to a lower bandwidth link or traffic from multiple inbound links that are switched to a single outbound link. Look at the "sh interface <BLAH>" and "sh controll e <BLAH>" any any line errors. Output queue - The number of packets in the output queue. After you issue this command, configure the port for any layer 2 properties. The command you are using is the show interfaces command. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Also, if there is a hub connected to the port, collisions between other devices on the hub can cause these errors.Platform Exceptions:Alignment errors are not counted on the Catalyst 4000 Series Supervisor I (WS-X4012) or Supervisor II (WS-X4013). I have a port that I believe is going up and down on a 2960X-port switch. This can happen in these situations: If a hub is connected to port 0/1, and a workstation connected to the hub transmits a packets to another workstation connected to the hub, port 0/1 does not forward this packet anywhere because the destination MAC resides on the same port. >> The example shows the log messages that result from a duplex mismatch between two Catalyst 6000 series switches: one that runs CatOS, and the other that runs Cisco IOS. The half-duplex side only expects packets at certain times, not at any time, and therefore counts packets received at the wrong time as collisions. Problems have been seen when you connect to devices manufactured before the IEEE 802.3z standard was ratified. >> "Port Status" in the output of "show port-security" - Cisco Theshow interfacescommand output up to this point is explained here (in order) : up, line protocol is up (connected) - The first uprefers to the physical layer status of the interface. Description:show interfacescounter. Note: Variables that can affect routing (for example, load and reliability) are not cleared when the counters are cleared. In order to check to see how long the port is in Up or Down status, use the show interfaces [interface id] command. FCS error count is the number of frames that were received with a bad checksum (CRC value) in the Ethernet frame. /V 58 0 R 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. If a port has a solid orange light, this means the software inside the switch shut down the port, either by way of the user interface or by internal processes. When the Gigabit Ethernet switching module is not fully utilized, you can balancee the port connections across port groupings to maximize available bandwidth. Cisco switch Link status Up, Protocol down - Super User Share Improve this answer Follow answered May 19, 2016 at 14:08 Ron Maupin 97.5k 26 112 188 The total number of frames which experience exactly one collision and are then successfully transmitted. You must apply configuration commands to the appropriate module. Always check the cable for marginal damage or failure. /Dests 10 0 R The traceroute facility determines the address of the first hop by examining the source address field of the ICMP time-exceeded message. Port Overview The Switch Ports section shows a basic view of the status of all switch ports. 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
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