Cheshire Cat Computing

Hi there,

I've installed MRTG bundle into Windows XP pro sp2 to capture all interfaces of my Cisco 1841 router. Surprisingly the setup is quite easy, It detects all active interfaces automatically just by updating the myrouters.txt file. However I found few glitches on the graph result.

It doesn't present the correct max bandwith speed on Serial0 interface. It only gives up to 125kbps, where it supposed to be 256kbps. So everytime the traffic reach >125, the incoming/outgoing line seems being cut-off (grey bar).

Meanwhile, it detects the Eth0 & Eth1 interface bandwith speed just fine (100mbps).

Which file should I look at to change my Serial0 max speed to 256kbps? and why is it not getting the correct speed at the first place?

Thanks advance for the enlightments. I'm quite a newbie on all these MRTG/RRD tools.




OOT: btw, anyone of you can advise which tool that can monitor the router traffic up to defining which applications or ports being used.

The bandwidth limit is extracted from your router via SNMP when the .cfg file is generated. Unfortunately, there is no guarantee that the router gives the correct value - it is quite possible that the link is 256k but the device reports 128k.

You can manually edit the generated .cfg file and fix the MaxBytes[] line if you want (remember this number is the max BYTES, so it is 1/8 of the bandwidth in bits). It may be possible to fix the number in the router but it would be very awkward (I know some ciscos allow you to set it internally to report whatever you want, regardless of the actual available bandwidth).

To monitor traffic split by port number, you will need a network traffic analyser that actually examines the packets at TCP level (a normal router just goes as far as IP level). For example, an RMAN probe. Some (very expensive) routers and switches have these built in but usually it would be a separate (expensive) device. Alternatively, set up a linux box with tcpdump installed and do some scripting magic - but it is not easy.

_________________
Steve Shipway
UNIX Systems, ITSS, University of Auckland, NZ
Woe unto them that rise up early in the morning... -- Isaiah 5:11

I wouldn't worry too much about what the BIOS reports as long as the CPU is operating at the correct speed in Windows. For example, the MSI 975X Platinum BIOS reports that my E6600 is running anywhere between 600MHz - 800MHZ. It's either incorrect or that is the actual speed the CPU is running at while in BIOS mode. However, Windows reports that my E6600 is running at the correct speed; 3.0GHz (333MHz x 9 multiplier).


http://www.virtualizationteam.com/virtu ... value.html