North American Network Operators Group
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Re: VOIP and QOS across local network and the Internet

  • From: Neal Rauhauser
  • Date: Tue May 15 20:08:59 2007


I've thought long and hard about this, mostly from the perspective of regional ILECs too small to implement MPLS.


QoS should be sold in 80k 'channel' increments. You, the carrier, don't care what the customer is marking as DSCP EF, you just accept and accelerate the first 80k x number of channels, then treat the rest as best effort. There should be a cost here as you have various management tasks - its not fire and forget like best effort service.

Your interior must prioritize the DSCP EF marked traffic ... but you open up the capacity engineering worm on your network. Can you easily predict maximums along paths and ensure they'll never be topped? Do you have queueing on all routers and switches that is rigged to support the plan?

The return path is *always* the problem. Sure, they can mark, you can accept, but how does the return sound? Do ISPs honor QoS markings across their network? Not the ones I touch, because they've often got public IP and private voice data riding in the same 802.1Q trunk, even though they may hit separate routers.


Its a big puzzle and the prize goes to whom ever figures out how to do it nice and neat in both directions. The big prize is, of course, declining voice profits as voice transitions to being just another internet app with no need for the regulated, media gateway & TDM telco world. At the end of the day the only phone companies left standing are going to be those who provide wireless phones, as there is significant capital investment required in such a plant. The wireline voice carriers are all going to slowly spiral into being nothing but ISPs.








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
traffic?

- 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.)

Thanks,

Rick Kunkel