Subject: [midcom] Client Vs. Proxy Traversal

From: "Pete Cordell" <[email-masked]>
Date: Thu, 22 Nov 2001 16:08:55 -0000

Bob,

This thread brings out something else...

Steve Davies wrote:
>> In this case the FANTOM client would have to handle
>> multiple simultaneous call setups and cleardowns. We judged a single
>> persistant tunnel for all call control from the FANTOM client to FANTOM
>> server was the most efficient use of resources.

To which Bob replied:
> Isn't this really the same as putting a proxy in the exterprise and having
> it connect to the proxy in the public network over TCP? Why is FANTOM
> better than adding a proxy? If FANTOM is present in the terminal, you have
> a tunnel for every terminal. If you have a FANTOM client, then all the
terminals
> need to send signalling to the FANTOM client. Doesn't that make it a
proxy?

By mentioning a proxy you raise an interesting issue.  In the enterprise
case,
FANTOM sits well where an ordinary proxy might sit, that is within the
boundary of the firewall installation (hence the name Application Proxy).
In
this respect it is augmenting the functionality of the firewall
installation.

This is not a pleasant thought if you only want end-to-end working.
However, the firewall has already broken that.  What it does mean though is
that the firewall is able to allow packets to/from the application proxy
to pass through that it might not otherwise allow from clients.  It can do
this in
the knowledge that the Application Proxy is forwarding only one
particular protocol, and the Application Proxy can also do all sorts of
other
stateful inspection exercises in order to check that things are as they
should
be.

It's much like adding an ALG to the firewall and NAT, except that in this
case it is located external to them.  As such it complements the firewall /
NAT functionality, but does not require the firewall / NAT itself to be
upgraded.  Therefore it can be quickly deployed, and is an ideal approach
for a pre-midcom solution.

On the other hand, if you deploy TURN or FANTOM on the clients, the
administrator has no way of knowing what they will be used for.  For a
number of environments this will not be acceptable, and won't lead to the
deployment of desktop VoIP.

Pete.

=============================================
Pete Cordell
Tech-Know-Ware
[email-masked]
+44 1473 635863
=============================================

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