VOIP and QOS across local network and the Internet

Rick Kunkel kunkel at w-link.net
Tue May 15 18:41:00 UTC 2007

Hello all,

We're getting an increasing amount of pressure from VOIP providers
colocated with us and from VOIP end-users to prioritize traffic on our
network.  From a network administrator's point of view, I am sensing that
this is the proverbial can of worms, and I'm hesitant to open it.  I
thought perhaps I could just do a quick survey, both of what people do on
their individual networks, and of what they know about others.

- Do you offer QOS services across your network for VOIP or other types of

- Do you do this on a per-customer basis, or is it done globally?

- If per customer, are there charges involved?

- Are there any major carriers that give preference to VOIP traffic?  
I've heard rumors that Global Crossing does.  I've also heard rumors that
almost all of them do.  I've also heard that almost none do.

- For those that offer QOS services for VOIP, is traffic classification
done by TCP layer protocol and port number?

- It's hard for me to imagine major carriers implementing any kind of
standardized classification.  For instance, if most carriers agree that
UDP traffic destined for ports Y through Z is VOIP and should thus be
treated in a more time-sensitive manner, what's to prevent the newest
version of BitTorrent to take advantage of this by fitting it's traffic to
that profile?  One of the things that makes VOIP so frustrating to the
telcos - data is data is data - seems to bite VOIP in the ass here.  Is my
thinking correct?  Or maybe traffic classification is happening at a
higher layer?

I can only imagine this issue growing larger.  With streaming audio and
video well-established, VOIP at the dawn of major acceptance, and Internet
TV, movies, and other real-time dependent applications on the near
horizon, it's looming large.

I know aspects of this have been brought up before, notably the whole "the
Internet core can't take it" conversation.  I'm hoping my questions are a
little more specific.  (However, I do find the aforementioned threads
quite fascinating, for the record.)


Rick Kunkel

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