Unjustified SHOULDs in CGN requirements
Simon Perreault <simon.perreault <at> viagenie.ca>
2012-06-01 15:24:06 GMT
During AD review of draft-ietf-behave-lsn-requirements it was pointed
out that many requirements are at the SHOULD level but do not include
justification for why they are not MUSTs.
Here's a list of all unjustified SHOULDs (there are 18). I'm asking the
WG for a justification for each of them. If a SHOULD isn't justified,
I'm going to turn it into a MUST. Note that I'm not looking for a
justification for the requirement itself. I'm looking for a reason why
we're saying SHOULD instead of MUST.
(1) REQ-3: The CGN function SHOULD NOT have any limitations on the size
nor the contiguity of the external address pool. In
(2) particular, the CGN function SHOULD be configurable with
contiguous or non-contiguous external IPv4 address ranges.
(3) REQ-4: A CGN SHOULD support limiting the number of external ports
(or, equivalently, "identifiers" for ICMP) that are assigned
(4) A. Limits SHOULD be configurable by the CGN administrator.
(5) C. Additionally, it is RECOMMENDED that the CGN include
administrator-adjustable thresholds to prevent a single
subscriber from consuming excessive CPU resources from
the CGN (e.g., rate limit the subscriber's creation of
(6) REQ-5: A CGN SHOULD support limiting the amount of state memory