VoIP over IPsec

Tue Feb 18 23:51:38 UTC 2003

On Tue, 18 Feb 2003, Stephen Sprunk wrote:

> > It also allows precomputation of the key stream, adding nearly zero
> > latency/jitter to the actual packet processing.
> 
> You fail to note that this requires precomputing and storing a keystream for
> every SA on the encrypting device, which often number in the thousands.
> This isn't feasible in a software implementation, and it's unnecessary in
> hardware.

You don' have to store the entire keystream, just enough to allow
on-the-fly packet processing.  Besides, memory is cheap. 100 msec buffers
for 100,000 simultaneous voice connections is an astonishing 80 Mb.

More realistically, it's 10k calls and 30 msec of buffering.

--vadim