[mrtg] Re: Monitoring true usage on a FDDI service

[Matt Katona]

I used to work at a company that had a 4 node FDDI ring, so talking the latin lingo is OK by me.

assumption: You spanned the 5500 FDDI interface to a 100 Megabit port monitoring

Are you doing BI port spanning (where the spanned port see's mirrored traffic from the dest as well as it's own from source)? 

FDDI is a flat protocal, so do you have any vlans/routers which would stop broadcasting to the FDDI port? Are you sure you are monitoring the right interface on the 5500?

Not to sound like you're off-kilter but make sure you are not monitoring a management network address. I don't know your topology, but are you monitoring the active side and not the fail-over side? 

Are you sure you are measuring the same stats? ie: MRTG reports on the SAME data as the sniffer (bits, bytes, blah blah blah)? 

Also, sniffer is real time where MRTG is a 5 minute sustained average. Are you sure you aren't seeing bursts of traffic on the sniffer? 


hope this helps!!

matthew

-----Original Message-----
From: Ray Warrier [mailto:Ray.Warrier at torex.com]
Sent: Friday, September 27, 2002 7:11 AM
To: mrtg at list.ee.ethz.ch
Subject: [mrtg] Monitoring true usage on a FDDI service


Dear All,
 
I have a query about true FDDI usage.
 
We have an FDDI ring with FDDI concentrators. Off one of the
concentrators interface we have plugged a
connection to a Cisco 5500 switch FDDI card.
I have asked MRTG to monitor the interface in/out octets on the Cisco
FDDI card.
The stats being produced looked extremely low, approx 1%
 
To confirm the stats are correct I plugged a Sniffer with an FDDI card
into the concentrator and saw that
the true utilisation was around 30%.
 
How can I get MRTG to collect all data transmissions and not traffic
destined for the Cisco FDDI interface ?
 
Additional information:
 
We are unable to run SNMP on the concentrator's because it is a third
party managed service. They are unwilling
to switch on SNMP.
 
Many thanks,
 

Ray

Network Consultant - Torex Health

P.O. Box 16, Kingswood Road, Prestwich, Manchester. M25 3BP

Email : ray.warrier at torex.com <mailto:ray.warrier at torex.com>   Web :
http://www.torex.com <http://www.torex.com/> 

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