[Sipping] draft-ietf-sipping-location-requirements-00

[Henning Schulzrinne <[e-mail]>]

I think it would be helpful to do a back-of-the-envelope calculation for 
a typical message exchange and geo value as to what delay a reasonable 
(GPRS, say) wireless channel would impose for the case that the proxy 
provides location information.

My back-of-a-grocery-bag calculation (even rougher than 
back-of-the-envelope) is:

100 kb/s data rate (optimistic)
10000 bit per message with location information

= 100 ms per transit of a location object across the air interface.

In the proxy-provides-location case, we'd need roughly 3 messages 
(INVITE-redirect-INVITE), two of which have location information, for a 
total of 300 ms, not counting the TLS setup time (which may or may not 
be required for each emergency call). This is close enough to the E-1 
requirement limit that somewhat more precise calculations are called for.

I also found it peculiar that the draft does not mention the 
signature-only (unencrypted) mode for S/MIME, which would not interfere 
with proxy inspection. (The chain of reasoning should probably be: need 
privacy + can't use S/MIME for privacy since proxies need to peek -> 
TLS, rather than the current non-sequitur.)

Henning

_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [e-mail] for questions on current sip
Use [e-mail] for new developments of core SIP