[Anima-signaling] GRASP and renumbering: suggestions

[Brian E Carpenter <[e-mail]>]

Hi design team. I expect you saw the recent messages about renumbering,
and you may have seen the big discussion in 6man about stable addresses.

I have two suggestions for GRASP.

1) In the description of discovery, we say this:

 After a GRASP device successfully discovers a Discovery
 Responder supporting a specific objective, it MUST cache this
 information.  This cache record MAY be used for future
 negotiation or synchronization, and SHOULD be passed on when
 appropriate as a Divert option to another Discovery Initiator.
 The cache lifetime is an implementation choice that MAY be
 modified by network Intent.

I suggest adding something more here:

 In some environments, unexpected address renumbering might occur.
 In such cases, the cache lifetime SHOULD be short compared to
 the expected address lifetime and a mechanism to flush the
 discovery cache SHOULD be implemented.

2) And in the API, I suggest that the 'discover' function
needs an optional 'flush' parameter, to specify that previously
discovered locators must be flushed first.

I am reluctant to add a TTL to discovery responses. It's a complication,
and experience with DNS is that resolvers often ignore the TTL.

Comments?

   Brian