[LINK] Resilient Broadband Network needed for Australia

[Kim Holburn]

On 2008/May/08, at 12:54 PM, Adrian Chadd wrote:
> On Thu, May 08, 2008, Kim Holburn wrote:
>
>>>> Of course if the standard VOIP protocols like SIP and H323 had been
>>>> written by someone with a clue about internet routing then VOIP  
>>>> would
>>>> be up and running in a big way already.
>>>
>>> Citation, please?
>>
>> I have no idea who created them.  I speak purely as someone who has
>> tried to route them.
>
> Right.
>
>> Why do they have source and destination IP addresses in the data?
>> Forcing a router doing what should be normal internet routing stuff
>> like NAT to root around in the data section of packets.  Also how  
>> hard
>> would have been to set up one UDP "stream" and put internal
>> application header data in the packets for the application to sort  
>> out.
>
> NAT wasn't a big deal when H.323 and SIP were designed.
>
> Seperation of payload and signaling is a big deal in the telco  
> world, and
> I bet H323/SIP tried to mirror that. It makes sense, if you live in  
> a world
> where everyone has a real IP address and you don't have devices in  
> the path
> which try to "track state". You have out of band signaling to  
> determine
> where the call needed to go; then the units would exchange media  
> (voice,
> video, whatever) directly without requiring the phone "switches" to  
> care.
>
> This hasn't worked out. Primarily, you need to bill for it somehow,  
> and from
> my basic exposure to such stuff, letting end-points talk directly to  
> each
> other makes billing minutes very difficult. So a lot of "VoIP  
> interconnect"
> that i've seen involves phone switches which act as media gateways  
> so calls
> can be accurately tracked; they're not just "routed"..

Yeah, so it's the attempt to add billing that's killing VOIP.  I  
remember someone telling me that more than half the telephone  
equipment and telco processes are just for billing.  I always wondered  
why a telco that was set up to use line rental instead of billing by  
the second or byte wouldn't be a much simpler and leaner and more  
economic operation.  Of course you'd have to get the monopoly to  
somehow release its strangle-hold on PSTN billing.  Seems to be a  
fingernail by fingernail operation.

Seems to me the whole "VOIP is not capable of emergency calls" thing  
is a beat up to try and claw back VOIP gains.  Telcos could do VOIP  
emergency calls if they really wanted to, or if they were forced by  
legislation to.  And they do often have to be forced, mobile number  
portability being one example.

> So its messy for telco, and its messy for end-point stuff (which is  
> what
> I think you were alluding to - NATs primarily being customer/ 
> business edges.)
> Damn. :)
>
>> To route this stuff properly requires a fairly sophisticated  
>> "tracker"
>> when it would have been simple to use the built-in capability of most
>> routers.
>
> I think you're "crossing the streams" a little. The protocol design  
> occured
> far before the proliferation of stateful firewalls and NAT devices,  
> back
> when the notion of having a device on the internet meant it was  
> assumed to
> be secure. Why this isn't the case is left as an exercise to the  
> reader.


As I said: it'd be nice to see a voice video streaming protocol  
created by someone with a clue about the modern internet.  H323, SIP  
and their family of protocols are so complex as to be difficult to  
really upgrade.  Not keeping application layer and transport layer  
stuff separate makes a protocol that is very difficult to add to, let  
alone use.  Almost the opposite of the underlying philosophy of the  
internet and internet protocol.

Of course because of the vested interests it probably won't happen  
until a proprietary protocol like skype that just gets through  
firewalls like they weren't there takes over.

Kim
--
Kim Holburn
IT Network & Security Consultant
Ph: +39 06 855 4294  M: +39 3494957443
mailto:kim at holburn.net  aim://kimholburn
skype://kholburn - PGP Public Key on request

Democracy imposed from without is the severest form of tyranny.
                           -- Lloyd Biggle, Jr. Analog, Apr 1961