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RE: [secdir] Review of draft-ietf-l2vpn-oam-req-frmk-09

2007-12-16 20:39:09
Tobias,
 
Once again, thank you for your comments and apologies for the delay in the 
response back. Please see inline responses:
 
Regards,

----
Dinesh Mohan


________________________________

From: Tobias Gondrom [mailto:tgondrom(_at_)opentext(_dot_)com] 
Sent: Friday, November 09, 2007 6:02 PM
To: secdir(_at_)mit(_dot_)edu; iesg(_at_)ietf(_dot_)org
Cc: ietf(_at_)ietf(_dot_)org; Mohan, Dinesh (CAR:NP02); 
sajassi(_at_)cisco(_dot_)com; sdelord(_at_)uecomm(_dot_)com(_dot_)au; 
philippe(_dot_)niger(_at_)francetelecom(_dot_)com
Subject: [secdir] Review of draft-ietf-l2vpn-oam-req-frmk-09



Hello, 

I have reviewed this document as part of the security directorate's ongoing 
effort to review all IETF documents being processed by the IESG.  These 
comments were written primarily for the benefit of the security area directors. 
 Document editors and WG chairs should treat these comments just like any other 
last call comments.


I studied the draft and a have the following COMMENTS and leave it at the 
discretion of the ADs whether they want to raise any DISCUSS based on these 
COMMENTS:


1. a few editorial: 

Section 1: 

s/relationship between two layered networks; Fault Detection at the server/ 
relationship between two layered networks, Fault Detection at the server

s/associated Pseudowires (PWs)/ associated Pseudo Wires (PWs) 

DM>> Agree with both comments regarding editorial updates.  


unclear statements:

Section 1: 

I found the following sentence imprecise and hard to understand: 

"Performance Management deals with mechanism(s) that allow

determining and measuring the performance of network/services under

consideration and notification of them."

DM>> For the sake of removing this ambiguity that you seem to be encountering, 
the authors are willing to make the following editorial change:
 
s/Performance Management deals with mechanism(s) that allow determining and 
measuring the performance of network/services under consideration and 
notification of them/Performance Management deals with mechanism(s) that allow 
determining and measuring the performance of network/services under 
consideration. 


Section 1.1: I would suggest to add CE and PE to the terminology of this 
document. It can only be derived from following a two-step indirect reference 
(via RFC4664 and then the reference mentioned there, which is stated as "work 
in progress"). For improved convenience the terminology should be referred 
directly from the document, or even better and more simple just add those two 
(CE and PE) to its Terminology.

DM>> Though the authors are not opposed to adding more terminology in this 
document, however, this typically becomes a challenge since we have multiple 
places where the same terms get defined. RFC4026 is the reference used for most 
terms that are a common place in L2VPN work. I am not sure where you are seeing 
the reference to "work in progress". The authors feel that no change is 
required for this given the references are in place, however, please let us 
know if this satisfies your comment. 

2. the document does not state its intended status: based on its content and 
its relationship to the two other referred RFCs 4664 and 4665, I would assume 
it is Informational. 

If this assumption is wrong, the intended status should be clarified ASAP.  

DM>> Your assumption is correct. This is meant to be Informational.  


3. The document does not seem to use RFC-2119 coherently. Throughout the 
document there are numerous places where I do not understand why authors use 
"must" instead of "MUST". One example: 

Section 6.10: 

Security implies that an OAM domain must be capable of filtering OAM frames.

=> should be: "Security implies that an OAM domain MUST be capable of filtering 
OAM frames."

And: 

"Also, OAM frames from outside the OAM domains should be either discarded (when 
such OAM frames belong to same or lower-level OAM domain) or transparently 
passed (when such OAM frames belong to a higher-level OAM domain)."

=> Should be at least: 

"Also, OAM frames from outside the OAM domains SHOULD be either discarded (when 
such OAM frames belong to same or lower-level OAM domain) or transparently 
passed (when such OAM frames belong to a higher-level OAM domain)."

In the context of the sentence I even wonder if "MUST" isn't more precise, as 
it MUST either be the first or the second. 

Equivalent in Section 7.10.: 

"Security implies that an OAM domain must be capable of filtering OAM frames."

=> should become: ""Security implies that an OAM domain MUST be capable of 
filtering OAM frames."

And: "Also,VPWS OAM frames from outside the OAM domains should be either 
discarded"

=> should become: "Also,VPWS OAM frames from outside the OAM domains MUST be 
either discarded"


Please note, my personal opinion is that RFC-2119-language usage seems 
incoherently throughout large parts of the document and not only in these two 
sections. But maybe my personal expectation is not correct for an Informational 
Draft in the context of this area. 

DM>> Please note that the document explicitly states the requirements which are 
called out as Rxx. There requirements are meant to be coherent with RFC-2119 
language and these are indeed covered as such. The text prior to the individual 
requirements is meant to provide context, justification as to why the 
requirement is needed. Therefore the authors feel that no changes are needed 
since the requirements' text is coherent with RFC-2119. Please let us know if 
this satisfies your comment.


4. The security Considerations (section 11) states that it does not need 
further security considerations as it only imposes requirements to solutions 
but does not describe the solutions themselves. In fact I believe this 
statement to be wrong in even two ways:

1. the initial abstract declares this draft is about the requirements AND a 
framework

2. even if the document would only be talking about requirements (and not about 
any implications on a framework), it should still clearly include security 
considerations for the requirements as they are already partially done in 
section 6.10 and section 7.10.  

DM>> The current text in section 11 states that "This document does not impose 
any security concerns since it imposes requirements on solutions to prevent OAM 
messages from leaking outside the OAM domains."  This statement does not imply 
that no security concerns are imposed since it is about requirements and no 
solutions. Rather, this states that no security concerns are imposed since the 
document imposes requirements on solutions to prevent OAM messages from 
leaking. And as you rightly point out, these requirements are indeed covered in 
section 6.10 and 7.10. Do you think an explicit reference to 6.10 and 7.10 in 
the above statement would help? Otherwise, the authors feel that no change may 
be required. Please let us know accordingly.

Last but not least, if the authors would still like to keep this section (11) 
as it is - which I would not recommend - they should consider to correct the 
following spelling errors:

s/ For additional levels of security, the solutions may be required deploy to 
encrypt and/or authenticate OAM frames inside an OAM domain however solutions 
are out of the scope of this draft./For additional levels of security, the 
solutions may be required to deploy encryption and/or authentication of OAM 
frames inside an OAM domain, however solutions are out of the scope of this 
draft.

DM>> We will modify this statement as:
s/ For additional levels of security, the solutions may be required deploy to 
encrypt and/or authenticate OAM frames inside an OAM domain however solutions 
are out of the scope of this draft./For additional levels of security, the 
solutions may be required to encrypt and/or authenticate OAM frames inside an 
OAM domain, however solutions are out of the scope of this draft.

5. Question: as the draft is heavily based on RFC4664 and 4665, I wonder 
whether they should not better be normative references instead of informative 
ones?

DM>> The authors are open to moving the two references to normative section, 
however, the rationale had been that both 4664 and 4665 are informational 
therefore could well be in either of the two locations. Please let us know if 
you feel strongly about this editorial change in this document.


Best regards, Tobias


__________________________________________
Tobias Gondrom
Head of Open Text Security Team
Director, Product Security

Open Text
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