Subject: RE: [ippm] Way to store traceroutes

From: "Sandra Tartarelli" <[email-masked]>
Date: Fri, 21 Jan 2005 15:31:17 +0100

Dear Stanislav,
 
from your (and others') comments, it seems to us that what we are trying to define here is a file format (rather than some data structures). In this case, we agree that we can omit storing per hop summaries.
 
We are also fine with storing simply the dump of the raw data, but we would  like to receive some more comments on this from the IPPM list.
 
If there's a general agreement on storing the raw data, then we will revise our initial proposal accordingly and submit it to the list again.
 
Regards,
Sandra
 
________________________________

From: [email-masked] on behalf of stanislav shalunov
Sent: Mon 1/17/2005 9:18 PM
To: Saverio Niccolini
Cc: [email-masked]
Subject: Re: [ippm] Way to store traceroutes

"Saverio Niccolini" <[email-masked]> writes:

> 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).

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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Dr. Sandra Tartarelli
Network Laboratories
NEC Europe Ltd.
Kurfürsten-Anlage 36
D-69115 Heidelberg, Germany

Phone:  +49 (0)6221 90511-32
Fax:     +49 (0)6221 90511-55

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From: stanislav shalunov <[email-masked]>
Date: 21 Jan 2005 11:48:06 -0500

"Sandra Tartarelli" <[email-masked]> writes:

> from your (and others') comments, it seems to us that what we are
> trying to define here is a file format

Note that the subject line says ``Way to store traceroutes''.  That's
what the question was asked about.

> (rather than some data structures).

I think it's both, but there can be working things that one might use
in a real implementation that need no standardization.  For example,
you might store the time it took you to read the file so far, but
there's no need to standardize format for that.  Or, you might store a
ring of last 1024 traceroutes, but there's no need to define precisely
how that ring should be organized.

The standardized data structure would benefit from having per-hop
summaries only if the amount of per-hop data is large.  Traditionally,
traceroute uses three packets per hop.  Storing their actual delays
seems like a better deal than storing the median, some interquintile
distance, and minimum.  Even if the sample is has a size of 5 or some
other small number, why would one even want these statistics stored
instead of the actual data?