Authors Mark Lindsey
SMTS at ECG

It's sometimes useful to saturate a network with simple traffic to test your QoS measures. What you want is something that'll send a controlled amount of bandwidth. A TCP-friendly connection won't work, because TCP slows down to the available amount of bandwidth. iperf from NLANR is one such tool. However, you have to have it running on both the sender and the receiver. I couldn't find anyth...

VoIP software and hardware vendors come from two camps: There are those who hide their documentation from the general public, and those who are open. Too many hide their documentation. Even if you register on their site as a guest, you can't get it. You usually have to be a customer with a paid support agreement. This includes Sylantro, BroadSoft, MetaSwitch, Acme Packet, General Bandwidth, P...

Update: This page desperately needed some diagrams. So I've added some. -- Mark, 2008 May 26 I'm a consultant for telcos and ISPs who do VoIP. Nearly all of my customers have diagrams. They're always Visio. We use their diagrams to help do network design changes or troubleshooting.At nearly every customer, as we start studying their diagrams in detail, they'll say, "wait, that's not right. This...

Monitoring tools come in these categories: Reactive Passive Monitoring Comprehensive Passive Monitoring Active Probing Reactive Passive Monitoring is when you run tcpdump/wireshark to troubleshoot individual call problems. This is the most critical to have -- but managing and analyzing real-time data streams is no easy skill. Comprehensive Passive Monitoring (CPM) monitors all calls, all the t...

There's a new discussion group, "BroadWorks-Discuss" for discussing the BroadSoft BroadWorks platform. It's one of the leading VoIP carrier software platforms out there, and this mailing list is intended to let people who use it, work with it, manage it, etc., discuss things. To subscribe, email broadworks-discuss-on@e-c-group.com

Jeff Pulver of FreeWorldDialup and Pulver.com and the VON Coalition got into it a bit with Brian Whitton of Verizon Labs at IPTComm 07 last week. Pulver argues that VoIP systems should be open, and new ideas should be tried. Brian Whitton argued that "business realities" were what caused Verizon to do the things it does -- like deploy FTTX using Voice over ATM at first. Both of them are probabl...

New York, NY: IPTComm 2007 at Columbia University was organized by Henning Schulzrinne, one of the co-inventors of SIP and an ongoing developer of VoIP applications. Schulzrinne commented that he thinks one of the big reasons people aren't developing new communication services is because there's nothing like PHP that can control calls. He's referring to the PHP programming language, which was o...

New York, NY: Jonathon Rosenberg, the principle inventor of SIP IPTComm 2007 at Columbia University, claims that we're not seeing new interesting VoIP-based services because people have been working on Voice services for a long time. All the obvious ideas have already been tried. It's not easy to have new useful ideas.

New York, NY: At IPTComm 2007 at Columbia University, Brian Whitton spoke about the network. He disagreed with Jeff Pulver's assertion that innovation wasn't happening because people didn't have guts. Whitton showed slides of Verizon's Fiber-to-the-home network that uses Voice over ATM, and showed the new architecture where SIP FTTX NIDs (ATAs) that talk to BroadWorks. The new architecture also...

New York, NY. According to Jeff Pulver at the IPTComm 07 conference in Columbia: The reason there aren't any advanced services is because everybody lost their courage. We took the closed network environment of traditional telcos and replicated it in VoIP. So now people can't easily build new services on top of VoIP services. "People need to have guts. People need to take changes. We got real, a...

The performance of the Cisco Catalyst 3750 is a funny thing. Software-based routing, called process switching, can only switch 2500-3000 packets per second[1]. But the box itself is rated at 6.5 million packets per second[2], using hardware-based switching. That's a huge disparity, larger than on Cisco's official "router" products. For example, the Cisco 2821 can process-switch 75,000 pps, and...

I'm no expert on telephone company management, nor the iPhone itself, nor the internal AT&T wireless-side organization. But I have been around numerous telephone companies, and have some ideas about AT&T and the iPhone. At the time of this post, lots of people are complaining of trouble activating the iPhone. My guesses about some sources of trouble: The iPhone doesn't have an externa...

The IETF SIP Working Group has a sub-group working on SIP Location Conveyance. The current draft isdraft-ietf-sip-location-conveyance This is proposed as a tool to enable SIP endpoints (such as SIP phones or ATAs) or their proxy upstream to convey the calling party's location to the called party. The imagined applications are: Calling an emergency number, like 911, so the first-responders know...

Consensus is growing among some system implementors that Verizon's patents for calling to PSTN and VoIP endpoints is tightly coupled to "direct media". This article discusses the three claims on which Vonage was found infringing and how it relates to other hosted VoIP carriers, like those using MetaSwitch, Sylantro, or BroadSoft. US Patent 6,104,711, Claim 20 talks about making calls directly t...

Verizon sued Vonage in case 1:06-cv-00682-CMH-BRP in the US District Court of the Eastern Virgina region. Verizon has won, for now. As people who make VoIP work, the engineers and operators of VoIP systems need some actual useful information to work with to build networks that observe Verizon's patents. This posting is just an attempt to collect some of that info in a useful place. The web i...