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Document: draft-ietf-ipfix-mib-variable-export-09.txt
Reviewer: Elwyn Davies
Review Date: 2015/11/14
IETF LC End Date: 2015/10/26
IESG Telechat date: 2015/11/19
Summary: Ready except for some minor nits, chiefly associated with the
unexplained use of 'magic numbers' that are defined elsewhere in the
IPFIX specifications (see comments on ss5.3, 5.4.2 and 6.3). I was
(however) impressed by the quality of the document, which is consistent
in its presentation and deals clearly with a complex (and, frankly,
pretty dry as dust) specification. Most of the points below are
primarily to make the document more easily accessible to people (like
me) with limited exposure to IPFIX. Caveat: I have read through the
examples (Section 6) but I cannot say that I have analysed them in gory
detail.
Apologies for the late delivery of this review. I missed the assignment
during the last call period. In the light of the quality of the
document, I don't think this should have any effect on the progress of
the document!
Major issues:
None.
Minor issues:
None.
Nits/editorial comments:
General: s/i.e./i.e.,/g (4 instances)
s/e.g./e.g.,/ (1 instance in s10)
s2, para 1: Probably good to provide a pointer to the doc/section where
Template Record and Data Record are defined as this section precedes s3
where the terminology is specified.
s4, para 2: s/non columnar/non-columnar/ (?)
s4, third para from end: s/One common type/Two common types/
s5, para 5:
However, future versions of IPFIX may export the required MIB
metadata as part of newer set versions.
Is the phrase 'newer set versions' a term of art here? Maybe change to
'newly defined version(s)' or maybe 'newly defined Set versions [or just
Sets]'?
s5.1, para after Table 1: s/encoding references/encoding reference/
s5.3, bullet points: To clarify Set ID entries in the figures describing
the various templates/data sets it would be worth noting the SetID(s)
that can be used with the various template and data records and a
reference to RFC 7011 Section 3.3.2.
I think that bullet 1 has Set ID 2, bullet 2 has Set ID 3 and bullets 3
and 4 have Set IDs from 256 upwards (implementation choice).
s5.4.2, last para and Figure 5: It would be helpful to remind people
that the value 0xffff/65535 indicates variable length encoding per RFC
7011 Section 3.2 and that the RECOMMENDED use of variable length
encoding for mibObjectIdentifier fields is indicated in subsequent
figures by placing 65535 in the relevant length fields. Presumably
Collector implementations MUST accept a specific length encoding in the
usual IETF spirit! It might be worth being explicit about this (this
might usefully be said in Section 8).
s5.7.2, para 1: The MUST ought to be qualified by 'except as allowed by
the caveat of Section 5.7.1'.
s5.7.2: is there any need to explain how withdrawal is achieved? I am
not an IPFIX expert so I am not aware how the withdrawal might be achieved.
s5.8, para 5: s/may be used purely use as a data type./may be used
purely as a data type./ ( I think)
s5.8, last para: is missing its terminal period/full stop. :-(
s5.8.1, last para: s/be exported/to be exported/
s6.2, bullet 2 after Table 3: is missing its terminal period/full stop. :-(
s6.2, 3rd from last para (top of page 40): s/encoded/encode/; It would
also be useful to point the reader back to the template for
mibObjectValueGauge in Table 23 where the encoding size is specified.
s6.3: This section is somewhat politically incorrect in that it deals
(only) with IPv4 addresses ;-)
s6.3, Table 4 (also Table 9): The aesthetics of this table could be
improved by reducing the width of the Object column by 7 characters and
reallocating them to the ID (+4) and mibObjectValue (+3) columns.
Similarly in Table 5, moving a character from the Entity column to the
Full OID column.
s6.3, Figure 28: For the benefit of less clued up readers, it would be
worth pointing out that this is a structured data type specification
using the 'undefined' (= 0xFF) semantic (RFC 6313, Section 11.4/11.4.1)
. It would also be clearer to s/=FF/=0xFF/g. Also applies to Figure 31
and Figure 42.
s10: The discussion I think effectively covers issues of privacy
inherited both from SNMP/MiBs and IPFIX but it might be worth putting in
the 'P word' and expanding a bit more on this subject to make it clear
that accessing MiB objects via IPFIX opens up a whole new opportunity
for privacy violations.
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