-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Stephen J. Wilcox Sent: Monday, February 10, 2003 12:56 PM To: Bill Woodcock Cc: nanog@nanog.org Subject: Re: VoIP QOS best practices
On Mon, 10 Feb 2003, Bill Woodcock wrote:
> > Looking for some links to case studies or other
documentation which
> > describe implementing VoIP between sites which do
not have point to
> > point links. From what I understand, you can't
enforce end-to-end QoS
> > on a public network, nor over tunnels. I'm
wondering if my basic
> > understanding of this is flawed and in the case
that it's not, how is
> > this dealt with if the ISPs of said sites don't
have any QoS
policies?
QoS is completely unnecessary for VoIP. Doesn't appear to make a bit of difference. Any relationship between the two is just FUD from people who've never used VoIP.
My conclusion too when I looked at this a couple years back.
However, its important that the backbone is operating "properly" ie not saturated which I think should be the case for all network operators, theres a requirement tho if the customer has a relatively low bandwidth tail to the network which is shared for different applications, its probably a good idea to make sure the voip packets have higher priority than non-realtime data... (this last comment is a suggestion, I've not actually tested this in a real environment, low b/w lab tests tend to exclude other traffic flows)
I have tested this in lab settings for video over IP (t1 with multiple 384k calls and data) , and came to that same conclusion. While it works on the tail and needs to be implemented bi-directionally (which never happens). There is no reason to implement QOS on the Core. Having said that, there still seems to be too many issues on the tier 1 networks with pacekt reordering as they affect h.261/h.263 traffic.
Steve