Date: Wed, 02 Jan 2002 18:16:35 -0600 From: Adrian Gonzalez <adrianbsd@globalpc.net> To: freebsd-isp@FreeBSD.ORG Subject: VoIP and PPP question Message-ID: <3.0.6.32.20020102181635.0100da70@globalpc.net>
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Hello I've been doing tests with a couple of Multitech MVP200 V/IP gateways (http://www.multitech.com/PRODUCTS/MultiVOIP/). Basically it's a gateway with 2 fxs/fxo/e&m ports and an ethernet port. The idea is to get v/ip going between two offices, with the following setup on both: Multitech V/IP Gateway connected via ethernet to a FreeBSD 4.4-STABLE box. Each FBSD box is running user ppp to connect to us (ISP) via a 3com ISDN modem. We receive them on our pm3's. Everything works great, but the real issue is QoS. A simple ftp download is enough to disrupt voice quality. I've toyed around with the "set urgent" option in user ppp, which is either being ignored or is not enough to fix the problem. I tried lowering the MTU on the link but that seems to break things for them. I'm considering trying dummynet for queuing, but I wonder if the problem has more to do with the packet size. I imagine it has to do with the big 1500ish byte packets clogging the 128k isdn connection for more than 100ms at a time, but I'm not sure why lowering the MTU from 1500 to 500 causes problems. When I lowered the MTU they started complaining about Ftp's suddenly hanging, and link slowdown in general. Anyone out there tried a similar setup? Any help greatly appreciated -Adrian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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