The ECG staff technical blog.
A lot of Network Security Expert grew up protecting conventional enterprise applications. Clients are PCs. Servers are web servers, or run MS Exchange. Maybe they get involved in web proxies. Perhaps they have to create a special rule for Microsoft SQL Server.
VoIP Security is entirely different. The ports, connections, services, and behavior are completely different than conventional PC s...
Last week, MetaSwitch (part of Data Connection Limited, DCL) launched the "Innovators" site. It's similar in spirit to BroadSoft Inc's "Marketplace". They're both intended to spur "Client Development".
Both are major VoIP software companies. MetaSwitch also handles hardware. Both keep their ordinary documentation locked in customer-only web sites. But both have released just a tiny bit of th...
I work with numerous telecommunications equipment providers who isolate their Development Engineers from customers -- and sometimes even from their internal staff. The Wall of Isolation becomes evident when you need to really understand how something works precisely.
All I want is to talk to somebody who can read the source code and tell me what it's intended to do:
A major VoIP software de...
Many people don't like using DNS to route VoIP traffic. I suspect other distributed applications have similar questions. They've had too many problems with DNS being reliable, or too slow for real-time call processing. In addition, many VoIP carriers use private IP addresses for their servers! This breaks Internet Engineering principles, and severely complicates name-to-address lookup services....
"Fring" is a Instant Messaging and VoIP client for the iPod and iPhone Touch. It's a free download, and I decided to try it.
Fring Setup
When you start Fring, you have to register for a Fring User ID -- before you even enter your IM, SIP, or Skype contact info. That suggested to me that it was doing this stuff through a central server.
I setup my MSN, AOL, and Yahoo IM contacts and se...
Occasionally I get to observe a client who has made a mistake; sometimes they come to us to help clean things up.
One such mistake is selling something that you don't have to sell. There are two forms of this mistake: the "Maximum Scale Error", and the "Unknown Cost Error".
Maximum Scale Error. Suppose you have a service, like Shared Call Appearance (SCA), also called Shared Line Appearance...
Thorbjoern Mann's book, "Time Management for Architects and Designers" has a lot of good advice that applies to people doing network, system, or software design! No, I don't design physical structures or objects, but it's still design. There's always more than one way to satisfy a goal. And making Design Decisions that harmonize to create a good system or network overall is important.
http://rc...
Psytechnics has a troubleshooting product that sounds neat. Expensive, but pretty neat.
Their marketing folks have sent me this email, announcing they'd teach me how to ensure "Enterprise-Quality" Video and Voice.
What is "Enterprise Quality"? To be honest, most "enterprises" I know do a lot of business over cell phones. Is cell phone quality what we're aiming for?
And even if we accept that "...
Service Providers often want a detailed Method of Procedure (MOP) for any change in their network. Some service providers, like Level(3), have Engineering people plan the procedure, while Operations people actually do the procedure.
This does encourage careful planning. But sometimes things go wrong; most MOPs have a back-out procedure, so that any changes can be reversed.
But wouldn't it be ...
VoIP service providers these days face the technical challenges of huge flexibility, and no single integrated solution with interop-tested partner devices. You can't just buy a "switch", plug in some TDM/SONET transport and turn up "smart remotes" made by the switch manufacturer.
Even integrated VoIP systems like MetaSwitch leave a lot of design space:
-- What signaling protocols?
-- Which of t...
The natural way networks are designed is "just do it". We just do whatever seems obvious; very little thought is given to design. Instead, neophytes think it's "just" a matter of configuration.
This approach leads to incomprehensibly complex designs. Cables going in every which way, poorly-planned fault tolerance, VLAN inconsistencies (e.g., VLAN 200 is one broadcast domain on this switch,...
Sales folks are a funny breed. It's a salesman's job to work to convince you to buy his product. But he's only willing to do so much work!
The amount of work he's willing to do is vaguely correlated to the amount of money he might make from you. For example, when I was at BellSouth, if I called Empirix to get information on their product, they wanted to get on a plane and come explain it t...
Wireshark is a really neat tool for analyzing phone calls. But when you load a 100 MB capture file of VoIP calls, you need much more than 100 MB of RAM. But how much more?
Here's a data point from which you can make a line: a 326.15 MB PCAP file contained lots of SIP, and a little RTP. This wasn't a raw capture file; I had thrown away a lot of the RTP and RTCP.
The file compressed to 121.1...
From the flight from Phoenix, AZ to Raleigh, NC: The BroadSoft Connections 2008 conference completed today. This is my third time at Connections.
The stated goal of the show is networking and dealmaking. The former is difficult to measure, but I suppose I did some of that. I know the latter occurred, and the work will occupy me for a while.
BroadSoft spent some time advertising the "xtend" pla...
How important is it to have a lab replicating your production (VoIP) environment?
Conventional wisdom says that everybody has a lab: some people just host their production users on it.
Having a lab incurs a lot of additional cost and work:
-- You have to buy the lab equipment, and the software.
-- You have to install and integrate the lab system.
-- You have to keep it up to date and secure.
...
Mark Lindsey