The IEEE ethernet specification forbids this bit to be set in any Ethernet frame. >> Acrobat Distiller 7.0 (Windows) In half-duplex environments, it is possible for both the switch and the connected device to sense the wire and transmit at exactly the same time and result in a collision. /Border [0 0 0] After you issue this command, configure the port for any layer 2 properties. << 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. << Every port on a Layer 3 switch configured to be a L2 switchport must also belong to a VLAN. /Outlines 3 0 R /Type /Annot l2trace {src-ip-addr} {dest-ip-addr} [detail]. /title (Checking Port Status and Connectivity) If neither auto-negotiation or hardcode setupseem to work, there can be a problem with the firmware or software on your NIC card. 12 0 obj %PDF-1.4 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). 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. i feel this command is only for trunks using DTP and not for access ports. The number of packets received incorrectly that has a CRC error and a non-integer number of octets (alignment error). CDP is useful to detect errors, as well as port and system statistics on nearby Cisco devices. This is helpful to diagnose a hardware problem on a module or port. Refer toConfiguring and Troubleshooting Ethernet 10/100/1000 MB Half/Full Duplex Auto-Negotiationfor details on how to resolve speed/duplex and auto-negotiation issues. Jumbo frames are not defined as part of the IEEE Ethernet standard and are vendor-dependent. In this situation, your bandwidth is used by the same frames over and over again, which leaves little room for legitimate traffic. Refer toConfiguring Jumbo/Giant Frame Support on Catalyst Switchesfor more information on system requirements, configureand troubleshootfor jumbo and baby giant issues. /Nums [0 32 0 R] After you issue the command, re-boot the switch or else the output of theshow interface status modulecommand shows the uplink port as inactive. << Refer to Table 1 for explanations of the error counter output. This high load of traffic oversubscribes the ports, which exhausts the input buffers and causes the Rx-No-Pkt-Buff counter and input errors to increase rapidly. The frames received that are smaller than the minimum IEEE 802.3 frame size of 64 bytes (which excludes frame bits but includes FCS octets) that are otherwise well formed.Common Causes:Check the device that sends out these frames. 0 Helpful Share Reply johnlloyd_13 Engager Options 09-27-2014 02:01 AM Hi, /Type /Pages There are other causes for late collisions besides duplex mismatch, but this is one of the most common reasons. This table shows the most common commands used to troubleshoot the port or interface problems on switches that run Cisco IOS System Software on the Supervisor. The show interface command displays the administrative and operational status of a switchport, input and output packets, buffer failures, errors, and so on. 4 0 obj Description:show interfacescounter. endobj If Rx-No-Pkt-Buff is zero or does not increment and the TxPauseFrames counter increments, it indicates that our switch generates pause frames and the remote end obeys, hence Rx FIFO queue depletes. When the keepalives are disabled, the CDP enables link to operate normally. Giant frames are defined as any frame over the maximum size of an ethernet frame (larger than 1518 bytes) that has a bad FCS. Therefore, it applies to only process switched traffic. The first up refers to the physical layer status of the interface. traceroute [-n] [-w wait_time] [-i initial_ttl] [-m max_ttl] [-p dest_port] [-q nqueries] [-t tos] host [data_size]. 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. Late collisions are a result of incorrect cabling or a non-compliant number of hubs in the network. (It still must be far less than one percent of the frames received.). This command displays what cards are present in the switch, the version of software they are that run, and what state the modules are in: ok, faulty, and so on. In addition, you can use Telnet from the switch to access other devices in the network. An advantage of PortFast is that this feature suppresses TCNs for a host port. Reduce the switch load if thenumber of packets in this field increase. For Cisco IOS on 2900/3500XL, 2950/2955, 3550, 2970 and 3750 series switches, theshow controllers Ethernet-controllercommand displays discarded frames, deferred frames, alignment errors, collisions, and so on. /Dest (G1060208) The numbers given for multimode fiber-optic cable refer to the core diameter. This example shows the source and destination MAC addresses specified, with no VLAN specified but with the detail option specified. /Subtype /Link Use theshow mac address-table dynamiccommand or substitute theinterfacekeyword. There are no specific requirements for this document. 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 . Typically this means frames up to 1600 bytes in size. CISCO MDS - Useful 'Show' Commands CONFIG: show startup-config show running-config show running-config diff show run |include host|gateway|ntp|fcdomain|http|telnet|zoneset|vsan show start |include host|gateway|ntp|fcdomain|http|telnet|zoneset|vsan show install all status show switchname show wwn switch show switch summary show version Loops can also be caused by a uni-directional link. /Type /Pages Make sure that both ends of the cable are plugged into the correct ports. 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. << The number of times the carrier was lost in transmission. The remote device is expected to stop / reduce the transmission of packets for the interval time mentioned in the pause frame. The number of times one 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. /Dest (G1020163) If collisions increase dramatically, this points to a highly utilized link or possibly a duplex mismatch with the attached device. 8 0 obj 1000BASE-T and 1000BASE-X Port Cabling Specifications, Category 5 UTP Category 5e UTP Category 6 UTP, 722 ft (220 m) 902 ft (275 m) 1640 ft (500 m) 1804 ft (550 m), 1804 ft (550 m) 1804 ft (550 m) 1804 ft (550 m) 6.2 miles (10 km). The switch will reflect that behaviour and you'll see a link go down/up two times. This is usually seen in half-duplex environments where the carrier is already in use when it tries to transmit a frame. /docType () This only happens under stress conditions but can happen with bursts of traffic on several ports. /Parent 14 0 R Small amounts of symbol errors can be ignored. 09-26-2014 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 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. This process continues until the TTL is incremented to a value large enough for the datagram to reach the destination host (or until the maximum TTL is reached). /PageLabels 8 0 R An alternative to this command (for Catalyst 6000, 4000, 3550, 2970 2950/2955, and 3750 series switches) is theshow interfacescard-type counters errorscommand which only displays the interface error counters. To enable SSH on the switch, perform this task in privileged mode: This example shows how to create the RSA host key: The nbits value specifies the RSA key size; the valid key size range is from 512 to 2048 bits. When the VLAN is already in fast aging, EARL cannot set the VLAN to fast aging, and aging timer set process is blocked. /Border [0 0 0] For general configuration information and additional information on how to troubleshoot, refer to Configuring and Troubleshooting Ethernet 10/100/1000 MB Half/Full Duplex Auto-Negotiation . Port status as seen in the color assist mode. The number of times the receiver hardware was unable to hand received data to a hardware buffer. For more information, refer to the UDLD: One-Way link problems section of this document. >> I don't think this command actually woks. 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). Same behaviour when a PC wakes up from sleep. /iaPath () Basically, up/down means the port is available for a cable/connection, but doesn't have one. 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. Try to find the offending device and remove it from the network. Generally, a one percent ratio of errors to total traffic is acceptable for half-duplex connections. The command output displays all active console port and Telnet sessions on the switch. So, a small number of No buffers frames is not a cause for concern. endobj Specify a particular module number to see information on the ports on that module only. If the VLANs are frequently in fast aging, check the reason for fast aging. The bytes counter includes both the data and MAC encapsulation in the error free packets received and transmitted by the system. A dribble bit error indicates that a frame is slightly too long.Common Causes:This frame error counter is incremented for informational purposes, since the switch accepts the frame. )"S\~hiTDsEBE#kX'#,6Ju%[LM_|tU];[uKXA_HC|{LjCLpEt[mD|Waj[Y!9!ITW B5i95l-'@ %!#5CmD&ny ['Pf`a]S
[zw W?u<=YX:9C^x@0~]/cA$?gB:WN0!ySp@(X17en}c\=E/miTgcgxF }=n 0&*ik:0zJQe4_S`;~x>m)#9]zf>6}Y=A))}\kg1Nz2?xe%;!49>8sr~GV)R[Ewpv#+bL~L {^gLg+ J*6FU !2voqy7=1*l2WQu$Hhp(to#S(49U:]wh%mdY6< This example of the show interface command shows theLast input neveron the TenGigabitEthernet1/15 interface. endobj This can also occur if a switch is connected to port 0/1 and starts to flood packets to all of its ports to learn MAC addresses. The number of received packets ignored by the interface because the interface hardware ran low on internal buffers. 06-22-2009 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. /Rect [162 354.8999938965 288.1799926758 366.1199951172] Late collisions can also indicate an Ethernet cable or segment that is too long. When you operate at full-duplex, errors in FCS, Cyclic Redundancy Checks (CRC), alignment, and runt counters must be minimal. UDLD can put a port in errdisable state when it detects a unidirectional link. Your network can send too many packets through this port for the port to handle at its current speed/duplex setup. Ensure that you have the correct cable for the type of connection you want to make. /Rect [162 490.9200134277 306.8999938965 502.1400146484] Aging Type : Absolute. 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. The SSH feature provides security for Telnet sessions to the switch. /Rotate 0 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 . The mode-conditioning patch cord is required for link distances less than 328 feet (100 m) or greater than 984 feet (300 m). Eliminate faulty patch panel connections. 26 0 obj Total output drops - The number of packets dropped because the output queue is full. 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). See the Common Port and Interface Problems section of this document for more information. Use theinterface-rangecommand to do this on multiple interfaces at once. << uuid:af7b7cc0-33fd-4b39-afce-898b51ab9cfc The total number of frames received whose length exceeds the System MTU, yet which have good FCS values. Packet loss causes retransmissions at the transport layer which in turn causes users to experience latency at the application level. If so, the port is good. endobj Refer toInterface/Module Connectivity Problemsfor more information on oversubscription. (Year 1993), 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. is the year/date not updated due to no NTP or local clock configured? Status is whether or not the interface is enabled administratively or if there is a physical connection to another device on the other end. /Rect [162 320.8800048828 286.5599975586 332.1600036621] That woud mean that the switchport would not go down even after not getting a response from the connected device for 20 minutes, if that is what you want: In addition, if you just want to get rid of the messages in your log, you can configure the logging discriminator below: logging discriminator LINKSTATUS severity drops 3 facility drops LINK mnemonics drops UPDOWN, logging buffered discriminator LINKSTATUS 100000logging console discriminator LINKSTATUSlogging monitor discriminator LINKSTATUSlogging host 192.168.100.10 discriminator LINKSTATUS, 05-11-2020 /Type /Annot The default CAM aging time is five minutes, which means that the switch flushes the table of learned MAC addresses every five minutes. Refer toUnderstand and Configure the Unidirectional Link Detection Protocol (UDLD) Featurefor configuration information on UDLD. 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. Description:show interfaces counters errors. Newer Cisco IOS contain a count parameter that can count lines which match a regex. For possible issues related to Field Notices, refer toField Noticesfor LAN and ATM Switches. Frames that increment at the upper end of this counter can exceedthe 15 collisions and can becounted as Excessive collisions. 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. 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. << This command displays the current configuration file of the switch. /Last 44 0 R 01:03 AM If the ratio of errors to input packets is greater than two or three percent, performance degradation can be noticed. INZA.@iQ/eY}`9@deB;r2.5I>/k^'`P(YTqSIuhBj6c/
8jTw{%jQtP:@\c"xJ
/iJ}#!s;Z7)z5A2AY+}qEVV"'W$Rd9}rol0)^}q{Fm>%,$N4A9$:[!\v;< @QOi"q8ITnV2abvyY;z2js^wB>_T m*wHQOWB-G`\ O;}ww ?PxWEs?\xKa[,bvZ,h"0.uB[bT\uOU|eL;HLQXdh8j>A . /Rect [162 337.9200134277 311.1000061035 349.1400146484] endobj In its operation, STP relies on continuous reception or transmission of BPDUs based on the port role. ), 2900/3500XL only.The number of times that a port received a packet from the network, but the switch did not have the resources to receive it. If the source and destination belong to multiple VLANs and you specify MAC addresses, you can also specify a VLAN. Note:The Catalyst 6500/6000 series switches do not clear the bit counters of an interface with theclear counterscommand. Cisco recommends that you disable the unicast flooding because it also ensure that no flooding occurs on the port once the MAC address limit is reached. All rights reserved. endobj See "Working with System Software Images," for the software image naming conventions that are used for the encryption images. The ports need to be in agreement as to what format they use on the link, or they do not understand each other. /R [41 63 585 621] endobj When you operate at half-duplex setup, some data link errors incrementin Frame Check Sequence (FCS), alignment, runts, and collision counters are normal. /Subtype /Link Also, some packet drop incrementation is normal and is the result of traffic bursts traffic. /Border [0 0 0] For Cisco IOS, use theshow interfacescard-type {mod/port}trunkcommand to verify the trunking configuration and Native VLAN. The port LED is set to the orange color and, when you issue the show interfaces command, the port status shows as Errdisabled. The interfaces that are "up" are in the connected state. No, it always shows this same date and time for all the interfaces (1993) even though the switch is configure with the correct date and time. /CropBox [0 0 612 792] The total number of frames whose length is less than 64 octets (which excludes frame bits, but includes FCS) and have a bad FCS value. This can be a sign that this segment is run at an inferior speed and/or duplex, or there is too much traffic that goes through this port. /Rect [162 371.8800048828 250.3800048828 383.1600036621] This is an invalid configuration. If the link light for the port does not come on, you can consider these possibilities: Connect cable from switch to a known good device. You can trace a Layer 2 path by specifying the source and destination IP addresses (or IP aliases) or the MAC addresses. This counter indicates the internal state of the Switching ASICs on the Supervisor and does not necessarily indicate an error condition. 05-11-2020 As an example, consider a scenario where a 1gig multicast stream is forwarded to 24 100 Mbps ports. 7 0 obj Do not disable auto-negotiation between switches unless absolutely required to do so, as physical layer problems can go undetected, which results in STP loops. Always use either Category 5, Category 5e, or Category 6 UTP for 10/100 or 10/100/1000Mbps connections. The size of this buffer is only 16 KB. Information is displayed about all Catalyst 4000 family, Catalyst 5000 family, and Catalyst 6500 series switches that are in the path from the source to the destination. << Trunk links between a switch and a router can make the switchport go down. This tests each device and verifies that the Gigabit interface functions correctly. That way, the VLAN can be seen in all interfaces. Destination unreachableIf the default gateway cannot reach the specified network, a destination unreachable message is returned. /date (2007-05-04T15:24:40.000-07:00) By default, Catalyst switch ports and interfaces are set to autonegotiate. - edited Check the IP address, subnet mask, default gateway, dynamic routing protocol configuration, static routes, and so on. FCS error count is the number of frames that were received with a bad checksum (CRC value) in the Ethernet frame. /Producer (Acrobat Distiller 7.0 \(Windows\)) Share /B [27 0 R 28 0 R] 22 0 obj Make sure each switch can see the end device MAC address in its Content-Addressable Memory (CAM) table. You can see what modules are installed, as well as the MAC address ranges and version numbers for each module, by using the show module command. 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. Undersize = frame < 64bytes. /PageMode /UseOutlines This will give you the last upinformation. You can use the [mod_num] argument to specify a particular module number to see detailed information on that module. /Dest (G1020140) This is only required if end-devices such as older Gigabit NICs are used which cannot support IEEE 802.3z. >> If the Rx is able to clear the Rx queue or reach low water mark within this interval, Tx sends out a special pause frame that mentions the interval as zero (0x0). Make sure both sides are in the same mode (both trunking with the same method: ISL or 802.1q, or both not trunking). If you see behavior that can only be considered strange, you can isolate the behavior to a specific box, and you have looked at everything suggested so far, this can indicate software or hardware problems. This does not tell you whether autoneg was used to achieve this. << sh ip traffic - all traffic through the Cisco sh controllers ethernet-controller gi1/0/1 phy - information about the SFP module into a particular port show vlan internal usage - used to show vlan sh inventory raw - in 4924 about stuck SFP seems to be the only way to see. . /Type /Catalog You must either enable or disable link negotiation on both ends of the link. 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). 9 0 obj An image can have become corrupted. This commanda display the 32-bit and 64-bit error counters per port or interface. In many cases, this is the result of a bad NIC. endobj >> In order to avoid packet drops on the device connected to the catalyst switch, issue theip cefcommand on the fast Ethernet interface of the device connected to the switch. 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. Failures of any test of a module or port show an 'F' in the test results. If an egress interface is over-subscribed, it is normal to see output buffer failures that increment along with Out-Discards. If you do not include a specific interface, it will show all the interfaces. To display summary information on all of the ports on the switch, enter the show port command with no arguments. It would be counted on theshow interfaceoutput for the appropriate physical interface. stream
Jumbos have larger frame sizes, typically > 9000 bytes. 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.
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