Follow the below . 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. This is usually seen in half-duplex environments where the carrier is already in use when it tries to transmit a frame. endobj Same behaviour when a PC wakes up from sleep. After 16 attempts have been made to send the packet the packet is dropped, and the counter increments. /First 12 0 R Note: There can be differences in the implementation of the counters across various platforms and releases. For fiber, make sure you have the correct cable for the distances involved and the type of fiber ports that are used. /CreationDate (D:19990615140519Z) /Dest (G1030299) Gigabit Ethernet has an auto-negotiation procedure that is more extensive than the one used for 10/100 Ethernet (Gigabit auto-negotiation spec: IEEE Std 802.3z-1998). Someone else in the community shared this with me quite awhile back. /Rect [162 456.8999938965 320.8200073242 468.1199951172] If a packet is sent from any other port, in the same VLAN as port 0/2, the packet is dropped. CISCO MDS - Useful 'Show' Commands - DavidRing.ie The runt counter only incremented when a frame less than 64 bytes was received. 22 0 obj It depends on the amount of the packets that are stored in the Rx FIFO buffer of the module ASIC. /Rect [162 354.8999938965 288.1799926758 366.1199951172] The same output show up for trunk ports as well as access ports. Reduce the switch load if thenumber of packets in this field increase. The cable can have encountered physical stress that causes it to be functional at a marginal level. When a port is in error-disabled state, it is effectively shut down and no traffic is sent or received on that port. On one of my 3750's ports that have never gone down show a 1993 timestamp, ports that have gone up/down have a recent (correct) date, 1 link ups, last link up on Sun Feb 28 1993, 16:01:20, 4 link ups, last link up on Tue Dec 02 2014, 14:51:11. 14 0 obj /P 6 0 R /P 6 0 R << The port is functioning well just odd to see these log. /Rect [162 388.9200134277 312.299987793 400.1400146484] These delays are caused by STP, trunking negotiations (DTP), and EtherChannel negotiations (PAgP). To identify a Layer 2 path, perform one of these tasks in privileged mode: l2trace {src-mac-addr} {dest-mac-addr} [vlan] [detail]. Without attenuators, the minimum link distance is 24.9 miles (40 km). /MediaBox [0 0 612 792] << ', Switch#show dtp interfaceDTP information for FastEthernet1/0/1: TOS/TAS/TNS: ACCESS/AUTO/ACCESS TOT/TAT/TNT: UNKNOWN/NEGOTIATE/UNKNOWN Neighbor address 1: 000000000000 Neighbor address 2: 000000000000 Hello timer expiration (sec/state): never/STOPPED Access timer expiration (sec/state): never/STOPPED Negotiation timer expiration (sec/state): never/STOPPED Multidrop timer expiration (sec/state): never/STOPPED FSM state: S1:OFF # times multi & trunk 0 Enabled: no In STP: no, Statistics ---------- 0 packets received (0 good) 0 packets dropped 0 nonegotiate, 0 bad version, 0 domain mismatches, 0 bad TLVs, 0 bad TAS, 0 bad TAT, 0 bad TOT, 0 other 0 packets output (0 good) 0 native, 0 software encap isl, 0 isl hardware native 0 output errors 0 trunk timeouts 1 link ups, last link up on Mon Mar 01 1993, 00:01:37 1 link downs, last link down on Mon Mar 01 1993, 00:03:13, The "sh dtp interface" command shows the same date for all interfaces. 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. This example of the show interface command shows theLast input neveron the TenGigabitEthernet1/15 interface. 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. The total number of receive frames that are discarded due to situation that the source route bit is set in the source address of the native frame. << Reduce the traffic load on the interface if you see the number of packets increase in these fields. Description:show interfaces counters errors. 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. 4 0 obj For Cisco IOS, use theshow interfacescard-type {mod/port}trunkcommand to verify the trunking configuration and Native VLAN. An excessive collision happens when a packet has a collision 16 times in a row. Refer toUnderstanding and Configuring VLAN Trunk Protocol (VTP)for more information on VTP. The first up refers to the physical layer status of the interface. The controller senses the wire and checks if it is not busy before it transmits.Common Causes:This is normal on an half-duplex Ethernet segment. 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. If you have a large number of deferred frames, or Out-Discard (also referred to as Out-Lost on some platforms), it means that the switch output buffers have filled up and the switch had to drop these packets. Description:show interfaces counters errors. Refer toTroubleshooting Cisco Catalyst Switches to NIC Compatibility Issuesfor details on how to resolve third-party NIC issues. Reduce the switch load if thenumber of packets in this field increase. This is useful to know when a dead interface has failed. To apply configuration commands to a particular port, you must specify the appropriate logical module. 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. These are the total number of packets received that were less than 64 octets long (which excludes frame bits but includes FCS) and have a good FCS value. The easiest way on Cisco switches is: show int status This will show you the link status for all ports The 45xx line has also some additional useful commands: show int link which will show you the last time the link was active. /Border [0 0 0] A broken fiber cable or other cabling/port issues can cause this one-way only communication. You must either enable or disable link negotiation on both ends of the link. To support authentication for Telnet with secure shell encryption, use the telnet keyword in the set authentication commands. If a router finds a TTL value of 1 or 0, it drops the datagram and sends back an Internet Control Message Protocol (ICMP) time-exceeded message to the sender. Also you can use (it is disruptive for the port): test cable-diagnostics tdr interface xx/yy and then /Border [0 0 0] Size/max means the current number of frames in the queue/the max number of frames the queue can hold before it is full and must start to drop the frames. The show interfaces status cli command shows you all interfaces. 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. endobj >> This is because the switch does not know that the connected device is a PC; the switch only knows that the port has changed the state. Verify that there is not a faulty cable. Spanning Tree Protocol (STP) loops can cause serious performance issues that masquerade as port or interface problems. /Dest (G1020163) If you turn the trunking mode to on (as opposed to auto or desirable) for one port and the other port has the trunking mode set to off, they are not able to communicate. /contentType () So, a small number of No bandwidth frames is not a cause for concern. Learn more about how Cisco is using Inclusive Language.
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