Centralization [LWN.net]

Centralization

Posted Aug 31, 2007 17:21 UTC (Fri) by lacostej (subscriber, #2760)
In reply to: Centralization by njs
Parent article: The Skype outage

This I already know. You don't need to convince me on the benefits of using :) I don't use much Skype, I have a SIP enabled phone at home. I just hope that an openmoko-like phone can fulfill my needs of an open phone.

But the initial discussion on this thread was:

> but no global database of all cellular users is needed.

to which I responded that the problem was the same today with SIP.

Can we agree on the 2 following sentences:

* the fact that Skype is a lock-in solution and doesn't interop with other VoIP solutions

* SIP also requires some sort of "global database" for each particular service provider, thus forcing you to login to a registrar to make use of *your* SIP id, meaning that if you registrar is down, you cannot be reached (but can make calls by reconfiguring your phone to use a different service provider)

(Log in to post comments)

Centralization

Posted Aug 31, 2007 19:47 UTC (Fri) by njs (subscriber, #40338) [Link]

Fair enough -- I admit I was picking the parts of the argument that made sense to me and responding to those, myself :-)

The initial post in this thread was not one that made any sense to me. Scalability is completely a red herring here; scalability is merely a technical concern. Do we have the hardware and knowledge to build a database that can scale to millions of subscribers? Yes, obviously, we do it right now. (AT&T might be only one of many cell phone providers, but I bet they're still routing more calls per second than Skype on its best day.) There are reasons that we have more than one cellular operator, but scalability is just not one of them.

Then the discussion went off in a different direction that I also don't understand. What is a global database for each particular service provider? I mean, if there are multiple service providers, your database is either global, or particular to one of them, it can't be both at once... For Skype, there effectively is only one service provider, so it makes sense to talk about their database being global, but for SIP there are hundreds, and you can run your own if you want (just like you can run your own email server). Like you say, SIP is a little more complicated than email because a call request needs to be deliverable in real-time, but this is just a technical detail.

I sort of get the impression that other posters were similarly confused about this part, and also guessed at what you were trying to say and then replied based on those guesses.

Centralization

Posted Sep 1, 2007 5:45 UTC (Sat) by rqosa (guest, #24136) [Link]

My point was that, with SIP, it's unlikely that there would ever be an outage for all SIP users; the failure of one registrar doesn't cause an outage for users on others. I think that was what the original poster meant (except that post referred to cellular phone systems, rather than SIP).