Best Regards
Zongpeng Du
About the comments:
Now I am more confused. This is new, rather than documenting existing
deployed practice. It is not standards track, so this is not an intent to
define something that can be deployed But it is being published as an archive.
Was this once intended to be standards track, but without sufficient interest or support
to complete it as a standard. Is this then reflecting that "we did a lot of work on
this and want to publish it in case there is future interest in doing something like
this"?
If so, that is fine. If it is something else, then it would be helpful to have
further explanation.
<zongpeng>Yes, this was once to be standards track. But market trend changed
while the work was going on, and then it was not finished.
Your understanding about "we did a lot of work on this and want to publish it in case
there is future interest in doing something like this" is right. </zongpeng>
I'm still confused about what message is used to convey this. Is it an existing
message in another spec, in which the AR List Element may be inserted? If so,
does that message already allow elements defined elsewhere, such as this one,
to be included? How would it be deciphered?
<zongpeng>We made some corrections about it. It is a mistake to include it
directly in the IEEE 802.11 WLAN Config. Response
Firstly, we change the Figure. Now, the IEEE 802.11 WLAN Configuration Response
message contains an alternate tunnel encapsulation message element, in which
the AR list element can be included.
Secondly, we rewrite the explanation under the graph. Now, it is said that "To
enable this, the IEEE 802.11 WLAN Configuration Response may carry the alternate tunnel
encapsulation message element containing the AR list element corresponding to the
selected AR as shown in Figure 5."
Thirdly, in Section 3.2. Alternate Tunnel Encapsulations Type, we add some
explanations:
" Besides, the message element can also be sent by the WTP to communicate the
selected AR(s)."
Fourthly, in Section 5.1. Access Router Information Elements, we add some
explanations:
" If the Alternate Tunnel Encapsulations Type message element is sent
by the WTP to communicate the selected AR(s), this Access Router
Information Element SHOULD be contained."
</zongpeng>
Another problem:
A message is mistaken used in the draft because of negligence, and we correct
it.
In current version, it is said that WTP Alternate Tunnel Fail Indication
(defined in this specification)
MAY be carried in the CAPWAP Station Configuration Request message
which is defined in [RFC5415].
However, it should be *WTP Event Request * message instead.
The CAPWAP Station Configuration Request message is sent by the AC to the WTP,
And the WTP Event Request message is used by a WTP to send information to its
AC.
-----Original Message-----
From: Paul Kyzivat [mailto:pkyzi...@alum.mit.edu]
Sent: Thursday, December 14, 2017 6:55 AM
To: Duzongpeng; draft-ietf-opsawg-capwap-alt-tunnel....@ietf.org
Cc: General Area Review Team
Subject: Re: Gen-ART Last Call review of draft-ietf-opsawg-capwap-alt-tunnel-10
On 12/13/17 3:56 AM, Duzongpeng wrote:
Hi, Paul
Please see inline.
Thank you very much for your careful review.
We have updated the draft accordingly.
If any problem, please connect us.
Best Regards
Zongpeng Du
-----Original Message-----
From: Paul Kyzivat [mailto:pkyzi...@alum.mit.edu]
Sent: Tuesday, December 12, 2017 3:48 AM
To: draft-ietf-opsawg-capwap-alt-tunnel....@ietf.org
Cc: General Area Review Team
Subject: Gen-ART Last Call review of
draft-ietf-opsawg-capwap-alt-tunnel-10
I am the assigned Gen-ART reviewer for this draft. The General Area Review Team
(Gen-ART) reviews all IETF documents being processed by the IESG for the IETF Chair.
Please treat these comments just like any other last call comments. For more
information, please see the FAQ at
<http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
Document: draft-ietf-opsawg-capwap-alt-tunnel-10
Reviewer: Paul Kyzivat
Review Date: 2017-12-11
IETF LC End Date: 2017-12-13
IESG Telechat date: TBD
Summary:
This draft is on the right track but has open issues, described in the review.
(Thanks for fixing most of the issues I raised in the previous round.)
Issues:
Major: 0
Minor: 7
Nits: 1
(1) MINOR:
In Section 1.3, if this document is intended to serve as a *historical* reference, then why isn't
then intended status "Historic" rather than "Experimental"?
<zongpeng>There have been discussions about it among the authors, chairs, and the ADs.
Finally, the "Experimental" type is decided.
According to https://tools.ietf.org/html/rfc2026#section-4.2, the historical
type means:
A specification that has been superseded by a more recent
specification or is for any other reason considered to be obsolete is
assigned to the "Historic" level.
Our document is a new one, so it is not very proper for us to declare a
historical type.
Also in RFC2026, it is said that
The "Experimental" designation typically denotes a specification that
is part of some research or development effort. Such a specification
is published for the general information of the Internet technical
community and as an archival record of the work, subject only to
editorial considerations and to verification that there has been
adequate coordination with the standards process (see below).
So we consider that the "Experimental" type is more suitable here.
And to avoid ambiguity, we have changed the "This experimental document is
intended to serve as a historical reference for any future work as to the operational and
deployment requirements." To
"This experimental document is intended to serve as **an archival record**
for any future work as to the operational and deployment requirements."
</zongpeng>
Now I am more confused. This is new, rather than documenting existing deployed
practice. It is not standards track, so this is not an intent to define
something that can be deployed But it is being published as an archive.
Was this once intended to be standards track, but without sufficient interest or support
to complete it as a standard. Is this then reflecting that "we did a lot of work on
this and want to publish it in case there is future interest in doing something like
this"?
If so, that is fine. If it is something else, then it would be helpful to have
further explanation.
(2) MINOR:
Section 3 contains:
Since AC can configure a WTP with more than one AR available for the
WTP to establish the data tunnel(s) for user traffic, it may be
useful for the WTP to communicate the selected AR. To enable this,
the IEEE 802.11 WLAN Configuration Response may contain the AR list
element containing the selected AR.
But "IEEE 802.11 WLAN Configuration Response" is not defined in this version of
the document. Seems like this may be a dangling reference from a prior version.
<zongpeng>Thanks for proposing the problem. We add some explanations for the
problem.
Firstly, change the sentence to " the IEEE 802.11 WLAN Configuration Response
may contain the AR list
element containing the selected AR *as shown in Figure 5*."
Secondly, change the Config. To Configuration in the Figure 5, and add
the [ AR List Element ] in the IEEE 802.11 WLAN Configuration
Response message.</zongpeng>
I'm still confused about what message is used to convey this. Is it an existing
message in another spec, in which the AR List Element may be inserted? If so,
does that message already allow elements defined elsewhere, such as this one,
to be included? How would it be deciphered?
(3) MINOR:
In Section 3.1, Figure 6 shows Tunnel-Type1 occupying the first 16 bits of a 32
bit value, and Tunnel-Type (2..N) all occupying the 2nd 16 bits of that value.
That doesn't work for N>2. I *presume* that the intent is that this be an array
of 16 bit values in network order starting with Tunnel-Type1, but that is not what
it says. Needs some work.
<zongpeng>Thanks for proposing the problem. We add some explanations for the
problem.
Firstly, add some explanations into the Tunnel-type Field.
Tunnel-Type: This is identified by value defined in Section 3.2.
*There may be one or more Tunnel-Types as shows in Figure 6.* Secondly, change
the graph to:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel-Type 1 | Tunnel-Type 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | Tunnel-Type N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</zongpeng>
Looks good.
(4) MINOR:
In Section 3.3 I find the wording of the usage unclear in the following:
The Alternate Tunnel Failure Indication message element is sent by
the WTP to inform the AC about the status of the Alternate Tunnel.
It MAY be included in the CAPWAP Station Configuration Request
message. ...
It is the way "MAY" is used here that causes me confusion, as if there
is some other way to achieve this goal. Perhaps the following would be
clearer:
The WTP MAY include the Alternate Tunnel Failure Indication message
in a CAPWAP Station Configuration Request message to inform the AC
about the status of the Alternate Tunnel.
<zongpeng> Thanks for proposing the problem. We revise accordingly.
</zongpeng>
Thanks.
(5) MINOR:
In Section 4.2 I find the usage of the term "Access Router (LMA) Information Element" confusing. I
find no definition of this as a distinct thing, so I gather the intent is that this is a particular usage of
"Access Router Information Element". I think this would be clearer to remove "(LMA)" from
Figure 10.
<zongpeng> Thanks for proposing the problem. We revise accordingly.
</zongpeng>
Looks good.
(6) MINOR:
Section 5.2 uses "ARs" and "ARs information" in ways that are unclear and improper grammar. IIUC "AR" in this document
means "Access Router", and so "ARs" should mean "Access Routers". It is used that way once in section 3.3, and once in
5.2. But several other usages in 5.2 are different, and seem to be intended to refer to "Access Router Information Elements". I suggest the
following change:
OLD
... If there are more than one ARs
information provided by the AC for reliability reasons, the same
Tunnel DTLS Policy (see Figure 14) is generally applied for all
tunnels associated with the ARs. Otherwise, Tunnel DTLS Policy MUST
be bonding together with each of the ARs, then WTP will enforce the
independent tunnel DTLS policy for each tunnel with a specific AR.
NEW
... If, for reliability reasons, the AC has provided more than one
AR address in the Access Router Information Element, the same
Tunnel DTLS Policy (see Figure 14) is generally applied for all
tunnels associated with those ARs. Otherwise, Tunnel DTLS Policy
MUST be bonded together with each of the Access Router Information
Elements, and the WTP will enforce the independent tunnel DTLS policy
for each tunnel with a specific AR.
In addition the mechanics of this "bonding" aren't entirely clear. This seems
to be covered by:
A: If A bit is set, there is an AR information associated with the
DTLS policy. There may be an array of pairs binding DTLS policy
information and AR information contained in the Tunnel DTLS Policy
Element. Otherwise, the same Tunnel DTLS Policy (see Figure 14) is
generally applied for all tunnels associated with the ARs configured
by the AC.
The above says "There may be an array of pairs". How is the array encoded and
how is its length specified? I'm guessing you intend:
When A=0:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Tunnel DTLS Policy Element Type| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |A|D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When A=1:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Tunnel DTLS Policy Element Type| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |A|D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |A|D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |A|D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where the number of repeats is equal to the number of AR addresses previously
specified.
This needs to be made much clearer. ISTM it would be cleaner to forget
the flag, and simply say this is always a list, where the last element
has no AR Information and provides options for any address not
previously mentioned. (But this isn't an option if it is documenting
existing usage.)
In Figure 9, I gather that "AR Information" means "Access Router Information
Element", and in this context it must be restricted to a single address, and must be the
address of one of previously specified AR addresses. If so, please say this explicitly.
<zongpeng> Thanks for proposing the problem. We revise accordingly.
The change is a little complicated, and is described following the comments.
Several people had edited the draft, so that there was some conflicts in the
description.
But the main opinion among the authors is the same. Thanks again for
the suggestion.</zongpeng>
The fix looks good to me.
(7) MINOR:
Section 5.3 has a similar construction to that in 5.2, with the same issues and
should get a comparable fix.
(8) NIT:
IdNits reports that the reference to RFC2460 in section 5.6 is obsolete.
<zongpeng> Thanks for proposing the problem. We revise accordingly.
</zongpeng>
Looks right.
About the (6) and (7), we choose to forget the flag as you have suggested.
However, it is found that it is not enough to just modify section 5.2 and 5.3,
so that section 5.4, 5.5, 5.6 are also modified to support information
providing of more than one ARs.
Among them, section 5.5 is a little different, because every GRE key should be
independent, and needs not to be the same.
Also for section 5.6, IPv6 MTU are not needed in the context of IPv4
environment, so there is no default value, neither.
For the detailed modifications, please refer to the new version of draft
attached.
Perhaps we will update the draft recently if it is ok for you.
Thanks,
Paul
