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« A Dark River Runs Through It | Main | links for 2007-08-20 »

August 20, 2007


The sad thing is that this is not just the price of free. Service on all sectors of telecom has gone down hill.

I pay good money to Wanadoo (former France Telecom) but still find I need to reboot my router several times a month and pay to wait on hold when I have more serious problems.

Not sure what the solution is, but free services on the one hand and the death throes of former telecom monopolies on the other makes for a bad spot to be a consumer!!

Wonder if there are equivalent examples in other industries or situations hit by a paradigm shift in technology?

In the case of this recent outage at Skype, the costless aspect of the app is irrelevant. Because it has been provoqued by an external factor, which, speaking of costs, is not free (MS Windows).
What is unacceptable here is the contrary : that a mass-market product for the use of which customers are charged a premium (think of the total cost of ownership of your production Windows PC...) causes troubles onto a third-party' s product.

What is remarkable here is the fact that Skype has been able to stay up and running all this time without any major problem for its customers - i mean, for its first 5 years of operation until last week' s bug.

Skype's issues last week are instructive for the entire industry. On the one hand, Skype has done a remarkable thing in generating a large user base very quickly. There are, however, important concerns about their architecture and approach, and questions have quite rightly been raised about peer to peer networks.

In fact, all Peer-to-Peer models are not created equal. Skype uses a different type of Peer-To-Peer network than most companies, based on SuperNodes. A SuperNode Peer-to-Peer system is one in which you rely on your customers rather than your own servers to handle the majority of your traffic. SuperNodes are just normal computers which get promoted by the Skype software to serve as the traffic cops for their entire network. In theory this is a good idea, but it does have unique vulnerabilities. Skype, as a company, has no physical or programmatic control over the most vital piece of its product when the network destabilizes for any reason.

Another issue with SuperNode models concerns system recovery after a crash. A SuperNode-based network can only recover as fast as new SuperNodes can be identified. Skype's formal post on Monday about the cause of its crash essentially confirmed this point.

Skype's model also creates usage issues. A Skype user who installs Skype on a university or corporate network agrees in the End-User License Agreement to let Skype route calls through his or her PC (and by extension the organizationís network). In many cases this is a violation of the terms of use the student/employee has agreed to with the university or corporate IT dept. It can cause legal and bandwidth issues.

Other companies such as SightSpeed use a standards-based Peer-to-Peer architecture built on SIP (the standard protocol as opposed to Skypeís proprietary protocol) that allows them to manage all the core functionality themselves. Telephony protocols such as SIP (which SightSpeed uses) were designed from the outset to be fault tolerant. Companies such as Microsoft, Cisco, Sprint/Nextel, Verizon, AT&T, Comcast, Time Warner and SightSpeed all ship standards based SIP software and hardware.

Skype's proprietary SuperNode architecture is what is risky. Peer-to-peer CAN be done right.

Aron Rosenberg
CTO SightSpeed

@Aron : thanks for the detailed explanation. Now I understand the difference between traditional SIP and Skype's own protocol. Do you think Skype could switch to SIP, easily ? Any guess how much efforts (technical, whatsoever) would it take for them ? I know you're rival, but Sun Tzu said : know you enemy better than yourself ;-)

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