Design draft, overall comments

- My first impression is that the document probably isn't very easy 
  to read for someone who hasn't followed the design discussions. 
  But I don't know what exactly should be done to help this, 
  and perhaps it's not even that important.

- The document should probably more explicitly say that the scope 
  is the design of draft-ietf-mobike-protocol, not any other work 
  items that MOBIKE WG may decide to work on.

- There's some overlap in the general background/motivation text
  and scenarios (sections 1 and 3) with draft-ietf-mobike-protocol.
  Perhaps it would be easier to say that this document is meant 
  to be read with draft-ietf-mobike-protocol, not alone.

- I'd suggest placing all instances of MAY/SHOULD/MUST etc. in 
  quotes (or changing them to lowercase) to show that we're just 
  describing that e.g. we decided to add this requirement in the 
  protocol, but this document itself is not imposing any 
  requirements for anyone.

Best regards,
Pasi