Hello Suresh,
Thanks for your review. We will update the draft in light of your comments, but
please see inline a few responses.
[snip]
* Section 2.1
-> Not sure if the word encoded is appropriate here.
s/hardware-encoded/usually implemented in hardware/
[CJ] OK.
-> These two sentences are hard to read and it is not clear what point
they are trying to make. Please consider rewording.
As such, the current state-of-the-art tends to confirm the said
separation, which rather falls under a tautology.
[CJ] What is meant by this sentence is that data and control planes have always
been separated from an implementation standpoint, hence the tautology:
commercial routers use a (S/W-based) routing engine for route computation
purposes, while packet forwarding functions are usually H/W encoded.
But a somewhat centralized, "controller-embedded", control plane for
the sake of optimized route computation before FIB population is
certainly another story.
[CJ] One of the main arguments of SDN proponents is that (1) the control plane
is separated from the data plane but, more importantly, (2) this separation
assumes a (logically) centralized control plane, which allows the use of
commodity H/W. From an implementation standpoint, this is different from
current router technologies, although there has been some vendors in the past
who tried to promote this kind of design (I remember Newbridge's Vivid
technology at the end of the '90s, for example). I'm not too sure about how we
can possibly re-word this, admittedly.
* Section 3.1
Not sure what this sentence is trying to convey. Can you clarify?
Some of these features have also been standardized (e.g., DNS-based
routing [RFC1383] that can be seen as an illustration of separated
control and forwarding planes or ForCES ([RFC5810][RFC5812])).
[CJ] What is meant here is that so-called SDN features have been there for
quite some time and some of them have been standardized, hence the couple of
examples above.
* Section 3.4
This direct access to some engines using a vendor-specific could be beneficial
to performance but may increase configuration complexity (in opposition to the
final goal in Section 4.1 of accommodating heterogeneous network technologies).
It may be worthwhile to add some text to the following paragraph in this regard.
[CJ] Fine by me, we'll add an extra sentence.
Maintaining hard-coded performance optimization techniques is
encouraged. So is the use of interfaces that allow the direct
control of some engines (e.g., routing, forwarding) without requiring
any in-between adaptation layer (generic objects to vendor-specific
CLI commands for instance).
* Section 3.5
This sentence is ambiguous
OpenFlow is clearly not the "next big thing"
Does this mean
a) OpenFlow is certainly not the "next best thing" (or)
b) It is not clear if OpenFlow will be the "next best thing"
Can you please clarify?
[CJ] option a is the right one. We'll reword accordingly.
* Section 3.6
This sentence about non-goals is unclear. What are the "respective software
limitations"?
o Fully flexible software implementations, because the claimed
flexibility will be limited by respective software and hardware
limitations, anyway.
CJ: The sentence means that there are S/W and H/W limitations respectively that
will always restrict the scope of claimed flexibility - another tautology, if
you will.
* Section 4.5
This sentence is long and complex, and the exact point it is trying to make is
not clear. Can you simplify/reword?
For example: while the deployment of a network solely composed of
OpenFlow switches within a data center environment is unlikely to
raise FIB scalability issues given the current state-of-the-art, data
center networking that relies upon complex, possibly IP-based, QoS-
inferred, interconnect design schemes meant to dynamically manage the
mobility of Virtual Machines between sites is certainly of another
scale.
CJ: Fair enough. We'll simplify the wording, e.g., "DC networks that may rely
upon OpenFlow switches are unlikely to raise FIB scalability issues.
Conversely, DC interconnect designs that aim at dynamically managing VM
mobility possibly based upon the enforcement of specific QoS policies may raise
scalability issues."
* Section 4.6
Can you clarify what risk is being assessed here?
o Assessing whether SDN-labeled solutions are likely to obsolete
existing technologies because of hardware limitations.
CJ: the risk is both technical and economical. From a technical standpoint, the
ability to dynamically provision resources as a function of the services to be
delivered may be incompatible with legacy routing systems because of H/W
limitations. From an economical standpoint, this is about assessing the impact
of deploying SND solutions for the sake of flexibility and automation on CapEx
and OpEx budgets.
Editorial
=========
* Section 3.3
s/policiy/policy/
CJ: thanks.
Cheers,
Christian.
_________________________________________________________________________________________________________________________
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce
message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
falsifie. Merci.
This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete
this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
modified, changed or falsified.
Thank you.
_______________________________________________
Gen-art mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/gen-art
