Subject: XML experience/learning in FACT/TIPC implementation

From: "Yang, Lily L" <[email-masked]>
Date: Wed, 26 Mar 2003 10:19:24 -0800

Hi, Jon --

At last week's IETF meeting you presented Ericsson's FACT/TIPC
implementation and demo.  That was very interesting. One of the motivations
of doing this implementation you mentioned is to understand/experiment with
using XML as the FE model data representation language.  I am very anxious
to know what is your learning/finding in that respect? As you know, one of
the questions we are struggling with on FE model is which modeling languauge
we should pick eventually. Can you share with the group your
learning/thoughts on this topic?

Thanks,

Lily

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From: Jon Maloy <[email-masked]>
Date: Fri, 28 Mar 2003 09:58:09 -0500

Hi,
Our experiences with XMLas representation language are generally
very positive. XML is well fit to express the commands and queries
needed in the protocol.
Our main concern from the beginning was performance, but our
experiments indicate that this is not  a big problem.

The specific measurements we did here shows that it was possible
to transfer and parse 42000 "add-routes"/s, when bundling 40 add-routes
into each transferred message. This measurements were performed
between two 2 GHz P-4:s.
With XML each add-route item is around 10 times larger than the
corresponding items in the FLEX protocol, and we have indications
that  this will cause the the whole transfer/parsing process to be an
order of magnitude slower than with 'native' FLEX or FACT.
We may find better parsers, and there is still a potential for
further optimizations in the transport plugin code, but frankly I don't
think this ratio will change significantly.

So the question we must answer is the following: Is a performance
degradation of ~10 times worth the price, given the extra flexibility
that XML provides over FLEX/FACT?

Regards /Jon

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From: Alan DeKok <[email-masked]>
Date: Fri, 28 Mar 2003 12:30:07 -0500

> very positive. XML is well fit to express the commands and queries

  There was also an 'xmlconf' or 'netconf' BOF, which met at IETF-56 on
Monday.  If we decide to use XML as a ForCES protocol, it would seem
that there may be significant overlap between the two groups.

> experiments indicate that this is not  a big problem.

  Assuming that the machines involved are powerful, and have sufficient
memory.  As Moore's law shows, this is probably a reasonable assumption,
given the timescales involved with creating a new protocol in a working
group.

> order of magnitude slower than with 'native' FLEX or FACT.

  The question is then whether this slowdown is significant.  If the
total bandwidth devoted to ForCES is minimal, then increasing it by a
factor of 10 is probably acceptable.

> that XML provides over FLEX/FACT?

  And given the extra cost of implementing more complicated parsers.

  For now, it looks expensive to me, but not outlandish.

  Alan DeKok.