[Anima-bootstrap] Brian: GRASP parameter for registrar discovery by proxy

[Toerless Eckert <[e-mail]>]

Hi Brian

In the anima bootstrap meeting we tried to figure out the necessary
GRASP message elements for discovery of registrars by proxies. And make
it extensible.

If you check:

http://etherpad.tools.ietf.org:9000/p/anima-boostrapping?useMonospaceFont=true
578 - 608

We may have a bunch of different possible proxy behaviors:

  - TCP circuit proxy in conjunction with HTTPs
  - UDP proxy in conjunction with CoAP
  - IPinIP proxy in conjunction with either HTTPs or CoAP

MichaelR's text was currently suggesting to indicate in the GRASP message
what the registrar supports via the locators:

    locator1  = [O_IPv6_LOCATOR, fe80::1234, 6,  <any,eg:443>]
    locator2  = [O_IPv6_LOCATOR, fe80::1234, 17, <any,eg:5683>]
    locator3  = [O_IPv6_LOCATOR, fe80::1234, 41, nil]

The first line would indicate TCP circuit proxy, the second UDP proxy,
the third one IPinIP proxy.

I am quite uncomfortable to indicate the desired proxy behavior
purely via the IP protocol field in a locator (6, 17, 41). It already
is IMHO underspecified, eg: unclear why the UDP proxy would (only) support
CoAP, and what actually the IPinIP stack supports (CoAP, HTTPs, ...).

So, how/where would we most easily indicate the stack in the GRASP
response ? For example:

    locator1  = [O_IPv6_LOCATOR, fe80::1234, 6,  <any,eg:443>, tcp-circuit]
    locator2  = [O_IPv6_LOCATOR, fe80::1234, 17, <any,eg:5683>, coap-udp]
    locator3  = [O_IPv6_LOCATOR, fe80::1234, 41, nil, tcp-ip-in-ip]
    locator3  = [O_IPv6_LOCATOR, fe80::1234, 41, nil, coap-ip-in-ip]

Thanks!
    Toerless