Absolutely, just execute a "clear counters" command. You will then get
a confirmation prompt asking if you sure you want to clear the counters
on all interfaces.
I would also append my previous comments to indicate that the switch
does show you when the counters were last reset on a per interface
basis. So, if you ask to get the output from a "show interface" command
(warning: it will be long), you will see the details of every interface
on the switch. What you would be looking for would be:
*
Last clearing of "show interface" counters: this tells you when
the counters for that interface were last reset. If it says "never"
then it basically means that the counters have not been reset since the
last time the switch powered on (counters are automatically 0 when the
switch powers on). If all the interfaces have the same information
here, then you can make some relative assumptions about the traffic to
ports. I would caution, though, that unless the switch is very static
(i.e. same things have stayed plugged in long term), the information may
not be helpful. It also is not helpful if the switch has been up
forever and usage patterns have changed. One final thing: if the last
rese time is "never" you can see how long the switch has been up with a
"show ver" (look for "switchname uptime is...").
*
x packets input, x bytes, x no buffer: this tells you how many
packets/bytes have come into the interface (received).
*
x packets output, x bytes, x underruns: this tells you how many
packets/bytes have gone out of the interface (sent).
You can then just take the input/output and add it together to get a
total. I would reiterate that this will give you some basic
information, but if you *really* want to keep track of that port MRTG
(or something similar) gives you the best information.
________________________________
From: David Lum [mailto:[email protected]]
Sent: Tuesday, May 05, 2009 11:43 AM
To: NT System Admin Issues
Subject: RE: Cisco Catalyst 2950 / 3550 info
Thank you! Is it feasible to reset all the port counters at once? It's
just a counter reset and it doesn't affect anything else right? I would
settle for asking him to reset the counters on all the ports and looking
at the volume two days later - it would be more info than nothing.
David Lum // SYSTEMS ENGINEER
NORTHWEST EVALUATION ASSOCIATION
(Desk) 971.222.1025 // (Cell) 503.267.9764
From: Mayo, Bill [mailto:[email protected]]
Sent: Tuesday, May 05, 2009 8:22 AM
To: NT System Admin Issues
Subject: RE: Cisco Catalyst 2950 / 3550 info
It really depends on what you are looking for. You can go into the
switch and use a "show interface" command to see statistics on that port
since it was last reset. Assuming that the port counters were all reset
at the same time, you could look at the input/output counters on all the
ports to see which one is the "busiest". You can also see the amount of
traffic over the last 5 minutes, but there is no other historical data
kept long term on the switch.
What MRTG does is polls the switch via SNMP at some interval and gives
you long term graphs. This is the better way to get good information
and it is true that it would require some configuration--SNMP would have
to be enabled on the switch, and MRTG would have to be configured to
monitor the relevant ports. Of course, you would have to wait some
interval to collect enough data to have meaningful results. How
hard/easy it is to configure MRTG to do this is directly related to the
person's level of comfort with MRTG; enabling SNMP on a switch is
trivial.
Bill Mayo
________________________________
From: David Lum [mailto:[email protected]]
Sent: Tuesday, May 05, 2009 11:09 AM
To: NT System Admin Issues
Subject: Cisco Catalyst 2950 / 3550 info
How hard is it to get a report on traffic for each port on Cisco 2950's
and3550's? I know our network guy uses MRTG for some things, but I'm
getting resistance to asking him to tell me which port is generating the
most traffic. The current response is "there needs to be a config change
to get that data".
I have experience with Dell managed switches (PowerConnect 5324 and the
like) and it's a simple matter to find which port has passed (is
passing) the most traffic, so I am skeptical about the amount of effort
required on a Cisco switch to achieve the same thing...
David Lum // SYSTEMS ENGINEER
NORTHWEST EVALUATION ASSOCIATION
(Desk) 971.222.1025 // (Cell) 503.267.9764
~ Finally, powerful endpoint security that ISN'T a resource hog! ~
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