Subject: RE: [ippm] Way to store traceroutes

From: "Saverio Niccolini" <[email-masked]>
Date: Mon, 17 Jan 2005 18:57:11 +0100

Hi Stanislav and all,

> -----Original Message-----
> From: stanislav shalunov [mailto:[email-masked]]
> Sent: 14 January 2005 17:45
> To: Saverio Niccolini
> Cc: [email-masked]; Juergen Quittek
> Subject: Re: [ippm] Way to store traceroutes
> 
> Saverio,
> 
> Your object summarizes the data on each hop rather than presenting the
> raw list.  This has the following problems:
> 
> * Space for only one IP number is provided.  What if different queries
>   with the same TTL elicit replies from different IPs?

I agree with you. With our representation we could have some problem if
this happens. We have to insert a structure taking care of this.

> 
> * The statistics (such as average RTT, max RTT, and sum of squares of
>   RTTs) are not robust.  This is not in line with the treatment of
>   delay in other IPPM documents, where percentiles are used.  I
>   believe that in the case of traceroute -- where the amount of data
>   is small for each hop -- there's no reason to not store the
>   individual delay, etc., values.

Ok. I see. Anyway I am not sure that not storing a summary for the hop
itself is a good thing. I would rather add a field for storing the
percentile of the delay for being in line with the treatment of delay in
other IPPM documents.

> 
> I'd argue for a list of probes for each hop instead of a summary of
> the given TTL.

If we are defining just a way to dump traceroute results into a file
then I completely agree with you.
If we are trying to store some more complicated results as the outcome
of some more complex summary representing the traceroute history then we
need also other fields as we defined.
Maybe we can review the record we had in mind to incorporate the two
vision (a list of probes for each hop and a summary for each hop).
Anyway I would like to ast the list for opinion on this. Any comment?

Best regards,
Saverio

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---

From: stanislav shalunov <[email-masked]>
Date: 17 Jan 2005 15:18:28 -0500

> vision (a list of probes for each hop and a summary for each hop).

I think it could be OK to store both the individual results and a
summary for each hop (even if I'd prefer simply the dump of the raw
data).

Could you perhaps explain where it would be useful to have a standard
format for both a summary and a list of individual replies for a given
TTL?  (This is an honest question; I really can't see any real
scenarios where such a standard format would come in handy.  OK,
here's one [not real]: one constantly runs traceroute in a full mesh
of 100 nodes with 10000 probes per TTL and accumulates a huge database
over the course of 10 years; then this database needs to be shared
with a different organization for the purposes of analysis.  This is a
really strained example, because the amount of data per hop is so
large.)

-- 
Stanislav Shalunov		http://www.internet2.edu/~shalunov/

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