[OSPF] Stephen Farrell's No Objection on draft-ietf-ospf-te-metric-extensions-09: (with COMMENT)

"Stephen Farrell" <stephen.farrell@cs.tcd.ie> Sun, 04 January 2015 02:07 UTC

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Subject: [OSPF] Stephen Farrell's No Objection on draft-ietf-ospf-te-metric-extensions-09: (with COMMENT)
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Stephen Farrell has entered the following ballot position for
draft-ietf-ospf-te-metric-extensions-09: No Objection

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These are mainly nits or questions, other than the
first.  That would have been a discuss if I knew of a
specific threat, but since this is just a general
concern, it's not a discuss. I'd appreciate a bit of
a chat about it though.

- I'd have thought that these TLVs would be sent more
often than others, and that (if enormous amounts of
money are in play) then use of OSPF authentication might
be more likely needed (or some equivalent security
mechanisms). I'd even speculate that if enormous amounts
of money are in play, then confidentiality may become a
requirement (since if I can observe say A bit settings
then that might give me insight into traffic levels -
sort of a lights burning at night in central bank
implies interest-rate change attack). Can you say why
none of that needs to be mentioned at all? Was any of
that considered by the WG? (Can you send a relevant link
to the archive?)

- intro: "extremely large amounts of money" aren't
usually explicit motivations for protocol features and I
hope that that continues to be the case. I'd encourage
you to remove that phrase. Similarly, "faster" is a fine
requirement but "fast than the competition" is not, so a
bit more wordsmithing might be good. (Those are, I
think, defensible points as we ought not over-specialise
our requirements, but to be honest I'd also be happier
if protocol development was not explicitly motivated
soley by increasing already-enormous amounts of money.)

- intro: saying the "measurement of delay SHOULD NOT
vary significantly based upon the offered traffic load"
is odd. Clearly the delay experienced can vary based on
the load, so I'm not sure what you're saying. And nor is
it clear why this is a SHOULD NOT, as opposed to a MUST
NOT. Maybe you need to explain that some more?

- section 3: Doesn't the A bit definition assume that
both senders and receivers know the thresholds (or
enough about those). That seems a bit odd to me, but I
expect you've thought it through.  Same thing with the
averaging period I guess (though section 7 does specify
a 30s default as a SHOULD). Or am I missing that one
could calculate those from the various TLVs that are
defined?  (I think I'm also not understanding bullet
point 4 in section 5 which may be related.)

- section 3: I don't get what "cannot be used for
fail-over purposes" means. I think you mean "ought not"
since a receiver can do what they want in any case.

- The security considerations of RFC 3630, from 2003, is
11 lines long. Has nothing affected OSPF security in the
last decade+ that would be worth noting here?

- In one response to the secdir review, [1] path
shortening attacks were mentioned - I'm not clear myself
if that's a deal here, but is text on that needed?

   [1] https://www.ietf.org/mail-archive/web/secdir/current/msg05354.html