-----Message d'origine-----
De : Christian JACQUENET
[mailto:christian.jacquenet@francetelecom.com]
Envoyé : mercredi 5 février 2003 11:39
À : 'te-wg@ops.ietf.org'
Objet : Comments on draft-ietf-tewg-measure-04.txt
Importance : Haute
Dear all,
Since the last call deadline for the aforementioned document
is now very close, here's a couple of comments on this draft
(sorry about the late show-up).
1. First of all, to answer Jim's question about the on/off
target topic, I think the document is perfectly on target, as
it represents a concise and valuable input for addressing the
TE measurement issue.
2. Section 1 (page 1) and in other sections as well: why not
simply talk about IP networks, rat
her than "IP-based"
networks, which may somehow introduce confusion?
3. Section 4.1. (page 4): I think a MPLS tunnel is an
*example* of a LSP, but there is no strict equivalence, since
classical MPLS/LDP operation also refers to the (dynamic)
establishement of LSP paths, without explicitly activating
MPLS TE functions. I would therefore suggest a slight
rewording of the definition of a path, stating that "a path
refers to an MPLS LSP, this LSP possibly being a
trafrfic-engineered LSP."
4. Section 4.2 (page 5): I think the definition of the
traffic volume (second paragraph) is too restrictive, since
the network may not have been *designed* to support the
volume of traffic measured at a given period of time (hence
the need for planning activities). I'm not a big fan of the
notion of "level of traffic" either, and I would tehrefore
suggest slight rewording such as "Traffic volume is the
amount of traffic measured at a gi
ven period of time. Such
measurement may/should be performed on a regular basis."
5. Section 5.2 (page 6): two comments.
5.1.: generally speaking, there are additional terms that are
defined in sections different from section 4 (such as "peg
count" (section 9.2) or "goodput" (section 8.2): why not
gather all these definitions in section 4, so as to provide
some consistency as far as the organization of the document
is concerned?
5.2. I can see a contradiction between the definition of
QoS/GoS (BTW, the notion of GoS is not that widely used by
Internet service providers - e.g. we prefer the "Class of
Service" wording for IP networks where DiffServ mechanisms
have been activated), as it appears in the second bullet
(referring to end users), and as it appears in the last
paragraph of the section (referring to inter-domain QoS). I
would either provide a reference to RFC 2475, or simply
delete the last sentence of the paragra
ph, which is rather
confusing ("QoS delivered to external peers by an autonomous
system" is a bit fuzzy to me).
6. Section 8 (page 9): in the second paragraph, "Currently,
there *IS* a number of 3rd-party...".
7. Section 8 (page 10): "...a passive measurement may be to
obtain packet inter-arrival times by time-stamping *succesive
packets of the offered traffic* at a selected point in the
network..." (I think it's more readable). The notion of
*offered* traffic should deserve some elaboration, otherwise
I would simply mention "traffic".
8. Section 9.1 (page 12): the notion of "MPLS path duration"
should deserve some elaboration.
9. Section 9.1(page 13):
- (first paragraph) "...and hence may *BE* used to derive..."
- I would summarize the note about the delay variation,
because it somehow unbalances the text with the rest of the
section, and also because the corresponding text can be found
in the ITU referenc
e, hence no need to reproduce it in the draft.
10. Section 11(page 16): I think the second sentence of the
paragraph is a bit too radical. How about: "This data may be
gracefully used for the dynamic computation and selection of
traffic-engineered routes that aim at complying as much as
possible with the forementioned demands, be they p2p or p2mp"?
11. Section 11 (page 17): in the second paragraph, I would
refer to section 8.4 instead of "section on path-based
measurement bases" for a better readability.
12. Section 12 (page 18): in the last sentence before section
13, I would quote draft-ietf-mpls-lsp-ping-01.txt as a reference.
13. Section 13 (page 19): (second paragraph) "...these
functionS to provide..."
14. Section 14.2 (page 21):
- COPS is not an information model per se, rather a protocol.
I would tehrefore suggest a reference to RFC 2753 instead.
- I would talk about "policy decision points" rather th
an
"policy control points"
- I would introduce the notion of PIB rather than "LDAP
repositories", to balance with the MIB quotation. After all,
LDAP is a protocol (among others) to access a
database/directory. BTW, you might want to take a look at
http://www.ietf.org/internet-drafts/draft-jacquenet-ip-te-cops-04.txt.
15. Before section 15 (page 22): I would be tempted to drop
some lines about some requirements on what could be the basic
characteristics of a protocol to convey traffic measurement
data. Something like:
"Although this draft focuses on the motivation for providing
Internet traffic measurement information, it is assumed that
this information should be provided to the participating
devices by means of a communication protocol that would be
used between the aforementioned participating devices and a
presumably centralized entity that would aim at storing,
maintaining and updating this information, as well as making
appropriate decisions at the right time and under various conditions.
This communication protocol should have the following characteristics:
1. The protocol should use of a reliable transport mode,
given the importance of configuration information,
2. The protocol architecture should provide a means for
dynamically provision the configuration information to the
participating devices, so that it may introduce/contribute to
a high level of automation in the actual Internet traffic
measurement operation,
3. The protocol should support a reporting mechanism that may
be used for statistical information retrieval,
4. The protocol should support the appropriate security
mechanisms to provide some guarantees as far as the
preservation of the confidentiality of the configuration
information is concerned."
Best regards,
Christian.
_________________ ________ ______ ______
/_____________ /__ /_ _ / / / / / Christian
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