From: Steven Ridder (saridder@xxxxxxxxxxx)
Date: Sun Jul 07 2002 - 10:21:34 GMT-3
Answers In-line---
1. Is "FRAME-RELAY VOICE BANDWIDTH xx" just used for voice over Frame
or is it applicatble to VoIP over Frame? I have seen examples both ways
(in books) and I am wondering if one may be a typo.
I think it has too do with VoFR if I remember correctly, but I'm too lazy to
look it up.
2. If I want to shape for VoIP, can I get away with setting precedence
bits on the IP dial-peer and enableing WFQ on every interum interface
on every interum router? I read somewhere that just turning on WFQ
would cause the precedence bits to be taken into consideration. Is this
just wishfull thinking on my part?
The WFQ algorithm does take IP Prec values into consideration. So if I have
a voice call with DiffServ EF value, it will certainly give me more avail BW
than an e-mail, but that's not enough when you are using voice/video.
WFQ is what I'd call a "shared" method. WFQ works like shares of a company.
If I join a startup, and the company has 8000 shares to give sway, and I
get 4000 of them, I'm looking pretty. I have 50% of the shares. If the
company grows and it needs to issue more shares to more employees, say it
releases up to 80,000 shares, my 4000 shares just became 5%.
WFQ woeks the same way. If there are just two types of traffic going across
a link, say an e-mail and a voice conversation. Say the voice had 50% of BW
guaranteed. My voice call is good and I'm happy. Then say some more people
came on line and began browsing the web, watching real player, etc.. The
WFQ algorithm has to allot them some of the BW to them as well, and it does
it by diluting the current allocations. So, the other flows get some BW
guaranteed and my 50% could go to 5%, destroying my call.
3. If there are multiple routers between the dial-peers, do we need to
apply our traffic-shapaing mechanism to all interum interfaces on all
interum routers?, (Queing, RSVP (or whatever mechanism we chose)) I
would think the answer is yes if we think the link could degrade the
quality of the phone calls. I would think that the only execptions
would be that we set the precedence bits, and compress headers only on
INGRESS into the IP cloud.
Yes, you need a common corporate policy to handle traffic.
4. How do we toggle "tc" interval? All the examples say 125ms. for DATA
and 10ms. for voice. Do we control it when we set the CIR and Bc ? Is
it the presence of voice keywords in the config that will throttle it
to 10s?
If I set CIR=64K and Bc=8K have I set Tc to 125ms?
If I set CIR=64K and Bc=640 bytes then have I set Tc to 10ms?
You are correct again.
If anyone knows any of these I would be very gratefull to hear the
answers.
Anthony Pace
-- Anthony Pace anthonypace@fastmail.fm-- http://fastmail.fm - One of many happy users: http://www.fastmail.fm/docs/quotes.html
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