rfc4941bis: Invalid addresses used by ongoing sessions

Fernando Gont <fgont@si6networks.com> Mon, 10 February 2020 09:20 UTC

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To: "6man@ietf.org" <6man@ietf.org>
From: Fernando Gont <fgont@si6networks.com>
Subject: rfc4941bis: Invalid addresses used by ongoing sessions
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Date: Mon, 10 Feb 2020 06:14:10 -0300
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Folks,

As currently specified, temporary addresses are removed when they become
invalid (i.e., the Valid Lifetime expires).

Section 6 ("6.  Future Work") of the draft
(https://tools.ietf.org/id/draft-ietf-6man-rfc4941bis-06.txt) still
keeps the following text from RFC4941.

6.  Future Work

   An implementation might want to keep track of which addresses are
   being used by upper layers so as to be able to remove a deprecated
   temporary address from internal data structures once no upper layer
   protocols are using it (but not before).  This is in contrast to
   current approaches where addresses are removed from an interface when
   they become invalid [RFC4862], independent of whether or not upper
   layer protocols are still using them.  For TCP connections, such
   information is available in control blocks.  For UDP-based
   applications, it may be the case that only the applications have
   knowledge about what addresses are actually in use.  Consequently, an
   implementation generally will need to use heuristics in deciding when
   an address is no longer in use.


I wonder if this text should be:

1) moved more into the body of the document and made a "MAY" (which for
TCP is very straightforward),

2) Be left "as is", or,

3) Removed from the document


The implications of #1 above is that it can't prevent long-lived
connections that employ temporary addresses from being torn down, at the
expense of possibly increasing the number of concurrent IPv6 addresses.

Thoughts?

Thanks!

Cheers,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492