Good point regarding non-congruence not necessarily meaning non-separation, and 
touché on margins (by which I presume you mean SS7 has massive 
overprovisionining for average traffic). 

However, the fact remains, it has proven itself to work for a lot longer, and a 
for much larger subscriber base, with far fewer systemic failures (especially 
on a per subscriber/expected availability basis), than the current Internet.

I notice you didn't answer my request for the peer reviewed literature to 
support your assertion.

To support mine I give (there are hundreds in the literature):

Gopel (Nokia): HSN and Multimedia Apps, 5th Conf, IEEE, 2002: Print ISBN: 
0-7803-7600-5 PP 161-166

Ramjee et al (Lucent Bell Labs): Comsware 2006: Print ISBN: 0-7803-9575-1 PP 
1-10

Khalios et al (City College of NY): IEEE Globecom 2003: Print ISBN: 
0-7803-7974-8 PP 3984-3989

Never mind all of Shannon's work and everything bell labs did in developing 
digital switching.

You can always have control traffic follow the same path in a different 
channel, so you get the same effect of physical interruption, and therefore the 
topography alerting of an interrupted link, without the issues of pathological 
traffic in the bearer channel interrupting your control traffic (as with ISDN 
subscriber trunks).



> -----Original Message-----
> From: Randy Bush [mailto:ra...@psg.com]
> Sent: Tuesday, February 16, 2010 7:56 PM
> To: Tomas L. Byrnes
> Cc: Nick Hilliard; NANOG list
> Subject: Re: BIRD vs Quagga
> 
> > As in SS7, which has successfully managed the phone system for
> > decades, where the control and data plane are explicitly separated?
> 
> and has such wonderful margins
> 
> and, btw, separation is not necessarily non-congruence

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