Subject: Re: Query on Meter-mib's

From: Nevil Brownlee <[email-masked]>
Date: Wed, 22 Sep 1999 11:10:52 +1200 (New Zealand Standard Time)

Hello Rohit:

>       I am electrical engineering student,National University
> of Singapore . I am building a QoS manager,for my final year B.Eng
> dissertation, that queries Netramet meters(that you have build) to get
> important parameters like FlowDataLastActivityTime for calculation of 
> QoS parameters.
>       From Meter-Mib RFC, I have figured out that meter stores data in 4-D
> table(or tree like form).The flowdata is stored according to the index of
> the flow.So,if flowdata has been assigned index(flowDataEntry)as 1, for a
> particular data value say DataFlowFirstTime it will store at 40.2.1.1.31.
> (please correct me if I am wrong in my thinking).But this has left me
> wondering, 

The flow table has three dimensions: flowDataRuleSet, flowDataTimeMark
and flowDataIndex.  That means that the flowDataLastTime value for
a particular flow will have OID 40.2.1.1.31.rr.tt.xx where rr is the
index (in the ruleset info table) of the ruleset which created the flow, 
tt is the timefilter value used to access the table (allows snmp GETNEXT 
to find the next flow active since tt) and xx if the flowindex.

>        Do the different meters located at different positions in a wide
> network store the flowdata for the same flow at different locations as they
> might assign different index to the same flow because of incapability among
> the meters to communicate to the other meter of the index it has assigned?

Yes.  The meters identify flows according to their rulesets, which may 
well be different for each meter.  If you had a small number of 
well-identified flows you could write a ruleset to set one of the 
'computed' attributes, say FlowClass, to a value which directly 
identified the flow - would that help?  The RTFM architecture doesn't 
consider how meters might talk to each other so as to dynamically 
allocate such a FlowClass for the same flow as observed on several meters.
This could be an interesting area for further development ..

> i.e Say meterX stores value of FlowdataLastActiveTime at 40.2.1.1.32 , then
>   meterY located somewhere after meterX but also measuring the same flow
> ,might actually assign FlowDataLastActiveTime at 40.2.1.2.32. 

flowDataLastActiveTime is the time the meter last saw a packet for a 
flow. It will be different when the packet is observed at different 
points around a network.

> Since my project requires RSVP parameters too, do I have to write whole 
> code similar to their code all by myself OR do they actually provide 
> the code free but i am not able to access it somehow . 
>      Has somebody done somework on inclusion of QoS attributes in netramet
> apart from CEFREIL institute?

Several people have mentioned that they are working on QoS measurement, 
but no-one has said they have open-source code available.  That means 
you'd have to write NeTraMet patches for yourself (which isn't all that 
hard, but there's certainly a lot of work in it).  Maybe others on the 
mailing list can help with this?

Cheers, Nevil

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| Nevil Brownlee                     Director, Technology Development |
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