[TriLUG] Managed & Unmanaged switches

[Brian Henning]

This is probably going to be right up Jon Carnes' alley:

Somewhere in the distant future, my current employer may be moving to 
VoIP telephony.  I remember hearing that it's best to have managed 
switching hardware supporting a VoIP infrastructure, as it allows a way 
to guarantee that the phones always have the bandwidth they need.  My 
question is thus:

Would it work to have one managed switch to serve the VoIP phones, which 
would also feed an unmanaged switch to handle other nodes?  Such as 
described by the following beautiful diagram:

}}}}
  }}}}}}}}}
Internet }}--[firewall]---[managed sw]----[unmanaged sw]
  }}}}}}}}}                   |    |              |
}}}}                         /    \              |
                             /      \         [Rest of the computers]
                  [VoIP phones]     |
                            [Some computers]

(Where of course "computer" means any node that isn't a VoIP phone)

It seems to me that the above arrangement would allow the managed switch 
to, er, manage the total allocation of bandwidth between outside and the 
phones, and all the traffic passing through the unmanaged switch could 
be clamped by the managed switch on its way to the outside if 
necessary...  Right?  And that would allow us to continue getting value 
out of our current hardware..

Or am I completely flawed in my reasoning?

Thanks as always!

Cheers,
~Brian