Hardware is C6k Mb Most of the time, a routing protocol needs to know the speed of the interface so it can choose the best route. Loopbacks are an important part of troubleshooting; they are used to isolate the fault on and end-to-end circuit especially when the circuit is down.
Keepalive set 10 sec Keepalives are used on the routers interfaces as hello mechanism to check the end to end connectivity to the other end. Routers interface used this mechanism to check the interface status. If you have no keepalive command its means that inerface status check mechansim in disabled and router will not transmit any keepalive packet on the link.
The last part of the line defines the type of the media. You may see many different implementations of flow-control technologies at different levels of OSI model e. If the clock mode of the near end of a link does not match the clock mode of the far end, the line protocol does not come up. The active and passive clock status is determined during the auto negotiation process before the transmission link is established.
Last input never, output never, output hang never Last input, output are the number of hours, minutes, and seconds since the last packet was successfully received or transmitted by the interface.
Note: This counter is updated only when packets are process switchednot when packets are fast switched. The clear counters command is used to reset interface statistics. Flushes is used to count Selective Packet Discard. SPD is a mechanism that quickly drops low priority packets when the CPU is overloaded in order to save some processing capacity for high priority packets.
The flushes counter in the show interface command output increments as part of selective packet discard SPDwhich implements a selective packet drop policy on the IP process queue of the router. Therefore, it applies to only process switched traffic. The purpose of SPD is to ensure that important control packets, such as routing updates and keepalives, are not dropped when the IP input queue is full.
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. These random drops are called SPD flushes. Total output drops is the number of packets dropped because the output queue is full. A common cause of this might be traffic from a high bandwidth link being switched to a lower bandwidth link or traffic from multiple inbound links being switched to a single outbound link.
For example, if a large amount of bursty traffic comes in on a gigabit interface and is switched out to a Mbps interface, this might cause output drops to increment on the Mbps interface. 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. Queueing strategy: fifo First-in, first-out FIFO queuing is the default queuing strategy that applies to all interfaces with more than 2 Mbps, or, in other words, E1 size or greater interfaces.
With the FIFO Queuing strategy, packets are forwarded through the interface in the order that they are received. Bytes: Total number of bytes, including data and MAC encapsulation, in the error-free packets received by the system.
No buffers: Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernet networks and bursts of noise on serial lines are often responsible for no input buffer events. Received broadcasts multicasts Total number of broadcast or multicast packets received by the interface.
For instance, any Ethernet packet that is less than 64 bytes is considered a runt. Giants: Number of packets that are discarded because they exceed the maximum packet size of the medium. For example, any Ethernet packet that is greater than bytes is considered a giant. Other input-related errors can also cause the input errors count to be increased, and some datagrams may have more than one error; therefore, this sum may not balance with the sum of enumerated input error counts.
CRC: Cyclic redundancy checksum generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. A high number of CRCs is usually the result of collisions or a station transmitting bad data. Frame: Number of packets received incorrectly having a CRC error and a noninteger number of octets.This document is intended to help determine why a port or interface experiences problems. Refer to Cisco Technical Tips Conventions for more information on document conventions.
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. The table describes the LED status indicators for Ethernet modules or fixed-configuration switches:.
Ensure that both sides have a link. 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. A link light does not guarantee that the cable is fully functional.
The cable can have encountered physical stress that causes it to be functional at a marginal level. Normally you can identify this situation if the port has many packet errors, or the port constantly flaps loses and regains link.
Make sure you have the correct cable for the type of connection you are making. Always ground the cables especially in new cable runs to a suitable and safe earth ground before you connect them to the module.
For fiber, make sure you have the correct cable for the distances involved and the type of fiber ports that are used.
Connections for transmit-to-transmit and receive-to-receive do not work. If you have device A connected to device B over a Gigabit link, and the link does not come up, perform this procedure. Both devices must use the same type of GBIC to establish link.
The numbers given for multimode fiber-optic cable refer to the core diameter. For single-mode fiber-optic cable, 8. The 9-micron and micron values refer to the mode-field diameter MFDwhich is the diameter of the light-carrying portion of the fiber. This area consists of the fiber core plus a small portion of the surrounding cladding.
The MFD is a function of the core diameter, the wavelength of the laser, and the refractive index difference between the core and the cladding. Distances are based on fiber loss. Multiple splices and substandard fiber-optic cable reduce cabling distances. The mode-conditioning patch cord is required for link distances less than feet m or greater than feet m.
The mode-conditioning patch cord prevents overdriving the receiver for short lengths of MMF and reduces differential mode delay for long lengths of MMF. Without attenuators, the minimum link distance is If either device has multiple Gigabit ports, connect the ports to each other. This tests each device and verifies that the Gigabit interface functions correctly. For example, you have a switch that has two Gigabit ports.
Wire Gigabit port one to Gigabit port two. Does the link come up? If so, the port is good. Does the port come up? If not, contact the TAC, as this can be a faulty port.
If steps 3 and 4 are successful, but a connection between device A and B cannot be established, loop ports with the cable that adjoins the two devices. Verify that there is not a faulty cable. Verify that each device supports There are a number of things we can check with the show interfaces command. Let me describe them:. If you have an MTU of set on a port, then any frame that attempts to ingress on this port that is larger than bytes will be dropped. If the port is set up to accept larger frames, then it will accept them.
This depends on the platform.
On the for example, the MTU cannot be changed on an individual interface, but is implemented globally. On the higher end catalyst switchesetc and always depending on the supervisor and IOS used, you can configure it on a per interface basis. In either case, you can verify the MTU on aper interface basis by using.
This is very useful because customer often ask for RFO reason for outage You can check interfaces to see last time it flapped. Then you can drill down into logs for the actual reason. You might find some additional helpful information there. As you get more familiar with Cisco, please share with us your thoughts concerning how Cisco compares with Juniper, Alcatel and other vendor devices as far as ease of configuration and use goes, it would.
Ask a question or join the discussion by visiting our Community Forum. Skip to content Search for: Search.Test an Ethernet Cable using Cisco Cable Diagnostics
When you use Ethernet, the protocol is normally up unless you configured port-security or BPDU guard. When a violation occurs, you might see err-disabled here. Hardware is Gt96k FE, address is c This is the amount of time required for the signal to travel from the sender to the receiver. This indicates how likely it is that a packet can be delivered or received succesfully.
Network Engineering Stack Exchange is a question and answer site for network engineers. It only takes a minute to sign up. I have a Cisco G switch. Are the interface counters reset automatically, recalculated in a specific interval 5 minutes?
I want to get hourly, daily, monthly, etc interface reports for the number of bytes passing through so I can charge a tenant a flat or proportional fee for the bandwidth they've used. Based on your comments, you are looking for the data usage over different time periods. You will need to use something like NetFlow or some other method to generate your reports. It defaults to seconds 5 minutes, and it can be set from 30 to seconds. Bandwidth is how any raw bits you can push across a link in a given time period, usually measured in bps bits per second.
Throughput is how much usable data you can push across a link basically, the bandwidth minus the protocol overheadusually measured in Bps bytes per second. That line is a few above what you provided. Interface counters in the UI reset 1 at reload, 2 when explicitly cleared clear countersor 3 when they roll over -- with 64bit counters, that's unlikely. To properly do traffic accounting for billing purposes, you need something like netflow to report how many bytes have actually moved across the interface, and what they were.
That will give you a great deal of detail and accountability. Just looking at an interface counter in the UI and even SNMP is not going to be enough justification for billing purposes. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Cisco interface counters, are the counters reset automatically? Ask Question. Asked 2 years, 6 months ago. Active 1 year, 3 months ago. Viewed 1k times.
The packets input and output have nothing to do with the bandwidth. If you are charging for bandwidth, then look at the BW Kbitwhich tells you what the bandwidth of the link is. You can adjust the bandwidth allowed for a customer by using QoS to shape and police. I need to know how much data the tenant is transmitting.
If I measure in 1m intervals I can get a very granular histogram together and invoice them like that. That would be data usage, and that is very different than bandwidth or throughput. You need to set up something like NetFlow to get what you want, You will not be able to pull that from the show interfaces command for any extended period of time. Active Oldest Votes. Note: Bandwidth is how any raw bits you can push across a link in a given time period, usually measured in bps bits per second.
So if I changed it to s, and captured readings and cleared the counters every 10 minutes to generate a nice histogram report, would that be an accurate means without going the netflow route?
Network Engineering Stack Exchange is a question and answer site for network engineers. It only takes a minute to sign up. On a large Cisco Catalyst switch stack, almost all switchports are patched. I need to identify the ports, which are not in use, for connecting further devices. Following switchports, cabling, patch fields and sockets to possible end devices is laborious and even then there could be temporarily used sockets.
Looking at the activity of port LEDs is not reliable, since a user device can be shut off. Now I can see my candidates, with actually 0 packets input over time, even if my expression matches numbers just ending with 0.
I could make it more perfect, but being easy to remember is also a benefit. The interface names right before each 0 packets input lines are my candidates. It can be good practice, to leave unused switchports shutdown. So it's easy to identify them using sh ip int bri or the like. And you don't run into problems if you use a switchport which was definitly shut off before. Just because a port is currently "down" doesn't mean someone has not been using it. Also just because the counters are currently zero doesn't mean it's never been used or not going to be used again in the near future -- counters can be cleared, and counters reset to zero at boot.
I've worked at ISPs and large enterprises, and documentation is the key to knowing what's what. Without it, random guessing will lead to numerous bad days Enterprise wiring closets can be a real mess; without documentation, tracing dozens of cables among thousands can be a pain and something as simple as port descriptions count.
The output parameter tells you when the port last saw traffic which is useful for identifying those ports that are only occasionally used. EDIT: Also worth noting for reasons beyond the scope of this question is that "Last input" is almost always "never". I like Stefan's answer but with this command line "sh int i Ethernet 0 packets input " which now grabs all Ethernet interface types and filters out non-zero numbers that happen to end in zero.
He mentioned that some fine tuning might be possible so this is just one example. Yes, the whitespace is needed.I have a switch with IOS of I cleared them and want to see what ports are not being used so I can move the users over to a new switch.
What is the correct form of show counters? If you're looking for ports being used you should be able to use command such as "show int description" this will at least tell you if a port is up or down. These pcs will show as "up".
Clear counters then whatch with show counters is what I am looking for.
Packet dropped counter in the show interface command output
Thats ok. Theres not that many people on that switch. I can get with whos on it as I bring them over. Buy or Renew. Find A Community. We're here for you! Turn on suggestions. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Showing results for.
How to show the interface counters in brief?
Search instead for. Did you mean:. Labels: Other Switching. I have this problem too. Tom Watts. If you're looking for ports. Maybe you have a. Maybe you have a gigabitswitch.
Then you should use sh int i GigabitE 0 packets output 0 packets input. Theres not that. Latest Contents. Created by hiarteag on AM. Why show ip bgp table is not showing any best path with expr Created by upadhyayambition1 on PM.
インターフェイス コマンド リファレンス ガイド、Cisco IOS XE Release 3 SE
Created by ciscomoderator on AM. Created by Kelli Glass on PM. However, there Create Please login to create content. Related Content. Blogs Networking Blogs Networking News. Content for Community-Ad. Follow our Social Media Channels.I need to monitor the number of packet drops per day, when I was using command " show int inc line drops " showing overall drops of the interface. But I've already cleared this packet drop issue.
So I need help to clear all the previous drop values. So please advise to help me. Go to Solution. View solution in original post. No need to worry to run these command on the production network. It just clear the counters of the interfaces and does nothing harm to the traffic flowing. Buy or Renew. Find A Community. We're here for you! Turn on suggestions. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for. Search instead for. Did you mean:. Cisco Community : Technology and Support : Networking : Switching : how to clear the interfaces counter in Khaleelur Rahman.
Labels: Other Switching. Everyone's tags 1. Tags: Catalyst I have this problem too. Accepted Solutions.
show interfaces status command
Leo Laohoo. Hall of Fame Community Legend. To clear ALL interface. InayathUlla Sharieff. Cisco Employee. Hi Khaleel,There is nothing. Hi Khaleel, There is nothing harm to your devices running the following commands. I did clear counters and now you can see the tod value is o. No issues with my traffic. If I could use the command. Looks clean now