Subject: [Dots] OP-005: draft-ietf-dots-requirements

From: <[email-masked]>
Date: Tue, 2 May 2017 07:39:58 +0000

Hi Andrew,

Below some comments about this text:

      DOTS clients SHOULD include a mitigation lifetime in all

      mitigation requests.  If a DOTS client does not include a

      mitigation lifetime in requests for help sent to the DOTS server,

      the DOTS server will use a reasonable default as defined by the

      protocol.

*         I suggest to change SHOULD to MUST so that clients are encouraged to always set a lifetime. Systematically setting (finite) lifetimes will help removing stale state entries.

*         The text can indicate that DOTS clients MAY set that lifetime to infinite but they MUST be prepared that infinite lifetimes may be discarded by the DOTS server.

"DOTS servers MAY refuse mitigations with
      indefinite lifetimes, for policy reasons.  The reasons themselves
      are out of scope for this document, but MUST be included in the
      mitigation rejection message from the server, per OP-004."

Should the text be updated to include the following:

*         DOTS clients should cache the maximum mitigation returned by the DOTS server for use in subsequent DOTS mitigation requests destined to that server? Doing so allows to offload the server by systematically returning an error message if the proposed lifetime is not honored.

*         DOTS servers should be configurable with a maximum mitigation lifetime. This configuration parameter can be global configuration, per-network, per DOTS client, ..

Cheers,
Med