[VOIPSEC] 4G Issue Map: signaling complexity

[Brian Rosen]

Well, more or less, I agree with you.

I definitely think users don't care about text or binary.  Carriers don't
care either.  Only implementors care.

I think we made a whole lot of mistakes with SIP, and with VoIP in general.
Security was one of them.  We didn't move fast enough on NAT traversal, but
it's hard, and we kept thinking there would be other things (like ALGs) that
would help us. Alas, not true, and now we have ICE, which is probably pretty
close to what Skype does bottom line.

I think Skype has taught me a lot.  I don't think many people on this list
get it:

You can have complete signaling security, every time.

You can have excellent quality audio, except when you go to the PSTN, and
even then, the average Skype out call sounds much better than the average
PSTN caller.  VoIP without wideband should never have existed.

You don't need many features, and some of the ones you need don't exist in
the PSTN (like portable phonebooks and chat).

Telephone numbers are starting to be less important

We still don't know what a sustainable revenue model is, but it's highly
unlikely to look like the current one.

What have you learned?

> -----Original Message-----
> From: Simon Horne [mailto:s.horne at packetizer.com]
> Sent: Thursday, August 24, 2006 7:09 PM
> To: Brian Rosen
> Cc: voipsec at voipsa.org
> Subject: Re: [VOIPSEC] 4G Issue Map: signaling complexity
> 
> 
> Brian
> 
> Customers don't care whether it's text or binary, they just care that it
> works and whether it can it deliver the solution to the customer
> requirements and that today includes PSTN integration, Security and NAT
> Traversal.  As SKYPE would say, arguing about which or what is better is
> just purely academic. Can you deliver the solution? The truth is after 10
> years with SIP we're all still scratching our heads.
> 
> Simon
> 
> At 06:00 AM 25/08/2006, you wrote:
> >Paul
> >
> >Re: Text vs Binary.
> >
> >I was there.  I was the IETF editor for the first Megaco RFC.  The design
> >was a compromise.  You can say, after the fact we could have done better,
> >and no doubt that was true.  However, the text guys will tell you the
> same
> >thing: if they could have ignored the binary guys, they could have done
> >better.
> >
> >The only think I have heard that MAY have some validity is that the
> binary
> >guys should have pushed PER instead of BER.
> >
> >I don't understand the compress SIP issue.   If you have a SIP device on
> a
> >network with hundreds of kilobits or megabits or gigabits of bandwidth,
> then
> >you can ignore compression; not worth it.  When you are on a device that
> has
> >kilobits of signaling channel, then compression is a good idea.  SIP
> >compresses well, without significant compute expense.  I don't think
> ASN.1
> >would compress well.  I'm not sure I've actually seen anyone try, but
> many
> >the normal compression tricks wouldn't work well except on the obvious
> >repeated URI stuff, which is text always.
> >
> >What we have discovered about text encoding is that they are much easier
> to
> >get right IN THE BIG PICTURE.  They are much, much easier to debug.
> >
> >The usual claimed ASN.1 advantage beyond message size is the automatic
> >syntax correctness.  My personal experience with that is that it's true
> on
> >the wire, but not in the implementation.  It takes more time to get an
> >interoperable implementation with ASN.1, because it takes more time to
> get
> >through the edit/compile/test loop, and it takes longer to diagnose.
> Once
> >you have the implementation working (and I mean interoperable) the
> >correct-by-construction syntax advantage goes away.  The thing that
> >surprised me the most was watching bakeoffs (sorry Pillsbury).  ASN.1
> based
> >bakeoffs are painful, text ones are much, much easier.  Total time
> clearly
> >favors text in a bakeoff.  Syntax errors are easy to diagnose and fix.
> >Semantic errors are much harder, and diagnosing them when you fumble with
> >your decoding tools is hard.
> >
> >Also, of course, we're a whole lot better with our ABNF parser tools now.
> >
> > > > If we were to start over in the IETF, the golden rule would be: This
> > > > protocol is NOT INTENDED to replace the PSTN, and any suggestion
> that a
> > > > feature is needed because the PSTN has it, or does it some
> particular
> > > way,
> > > > is sufficient reason for outright rejection of the feature or
> method.
> > >
> > > :-)  Yes and no.  When the user attempts to call a remote party and a
> > > recording says "the number you've dialed has been disconnected" is
> played,
> > > that needs to be heard.  It's either that, or devices have to process
> a
> > > lot
> > > of different (and equivalent) error codes.
> > >
> > > I was once using a SIP phone that would not properly play in-band
> > > announcements.  It was several days later (when I used my mobile
> phone)
> > > before I discovered why the phone just kept ringing and ringing.
> >Thank you.  Couldn't have picked a better example.
> >
> >The bell heads forced sip to implement early media, because they have a
> very
> >broken billing system, that they insisted had to be copied.
> >
> >Your problem was your phone did not play early media.
> >
> >The sip mechanism is that the end device gives you your error; there are
> no
> >announcements in audio form played by the far end.  What if you were
> calling
> >someone with a text phone because you are deaf?  Your phone could text
> you
> >the proper message, the far end can't.
> >
> >If you want media, complete the call.  That's because SIP is a session
> >establishment protocol, and the media is the session.  If you want media,
> >create a session.  That, in and of itself, is not the problem.  The
> problem
> >is the BILLING.  They want the session to NOT be established, and yet
> they
> >want (one way, if you please) media.
> >
> >Early media is a very, very bad idea, and has caused untold grief and
> >complication in SIP.
> >
> >
> >
> >
> >_______________________________________________
> >Voipsec mailing list
> >Voipsec at voipsa.org
> >http://voipsa.org/mailman/listinfo/voipsec_voipsa.org