Security-Requirements: alternatives?

[Gorry Fairhurst <gorry@erg.abdn.ac.uk>]

Haitham, I-D Authors, List,

One of the issues we need to be clear about in preparing for a WG 
adoption of the security requirements I-D is the possible alternatives 
that have been proposed/implemented in other standards organisations.

Could you summarise the methods that have been proposed for MPEG-2 
transmission networks that provide equivalent L2 security functions, and 
say which to your knowledge has actually have been implemented in systems?

Thanks,

Gorry