Subject: RE: Last Call: 'Definitions of Managed Objects for Middlebox Communication' to Proposed Standard (draft-ietf-midcom-mib)

From: "Romascanu, Dan \(Dan\)" <[email-masked]>
Date: Mon, 7 Aug 2006 15:47:11 +0300

1. Is the 'strict' SNMP terminology intentionally avoided in Section 4.2
and associated diagrams, and why? Meaning why do we say 'SNMP get
message' instead of 'SNMP GetRequest PDU', etc. ?
2. Section 5.3.1
> The MIDCOM MIB module does not require a middlebox to implement
   further specific MIB modules for supported middlebox functions, such
   as, for example, the NAT MIB module [RFC4008].
 
This should probably be 'further specific middlebox (NAT devices,
firewall) MIB modules'

3. Object midcomRuleAdminStatus

>     midcomRuleAdminStatus OBJECT-TYPE
       SYNTAX      INTEGER {
                       reserve(1),
                       enable(2),
                       notSet(3)
                   }
...
 When retrieved, the object returns the last set value. If
            no value has been set, it returns one of the two possible
            values."
       DEFVAL { notSet }

I do not understand what are the 'two possible values'. What happens of
a retrieval happens before the object is set for the first time? 

4. Several DESCRIPTION clauses (e.g. midcomRuleAdminStatus,
midcomRuleStorageType) include SNMP-specific error messages when
describing the behavior of the object. This is OK, as the MIDCOM-MIB is
designed to be used with SNMP as MIDCOM protocol, yet I would include a
note on this subject because this is not customary within other MIB
documents which are written with a protocol-independent orientation. 

5. What happens with the object midcomRuleObjectTime when
midcomRuleObjectType is permanent(4)? The DESCRIPTION clause of the type
object suggests that time is read-only. With DEFVAL 0 this means
automatic destruction of the row at the end of the transaction. Is this
the desired behavior, or did I mis-understand something? 

6. I do not feel comfortable with the DESCRIPTION clause of
midcomRuleError RECOMMENDing values for this object without defining
what behavior each message is supposed to cover. This type of object is
not interoperable, and this would be made clear if it was said that
these are examples rather than RECOMMENDations. 

7. Another side-effect of the midcomRuleObjectType being permanent(4) is
that the permanent rules cannot be applied to interfaces, so they can be
only global. Same about transport protocol and other read-write objects.

8 . There is no DEFVAL for midcomRuleFlowDirection 

9. 
>          Valid values for midcomRuleTransportProtocol
            other than zero are defined at:
            http://www.iana.org/assignments/protocol-numbers

Does this need a new type of registry from IANA? There is nothing in the
IANA considerations about this. 

10. What notification needs to be sent when midcomConfigIfEnabled is set
to false? Neither the DESCRIPTION of the object nor the one of the
notifications do provide any clue. 

> -----Original Message-----
> From: The IESG [mailto:[email-masked]] 
> Sent: Thursday, August 03, 2006 8:09 PM
> To: IETF-Announce
> Cc: [email-masked]
> Subject: Last Call: 'Definitions of Managed Objects for 
> Middlebox Communication' to Proposed Standard (draft-ietf-midcom-mib) 
> 
> The IESG has received a request from the Middlebox 
> Communication WG to consider  the following document:
> 
> - 'Definitions of Managed Objects for Middlebox Communication '
>    <draft-ietf-midcom-mib-08.txt> as a Proposed Standard
> 
> The IESG plans to make a decision in the next few weeks, and 
> solicits final comments on this action.  Please send any 
> comments to the [email-masked] or [email-masked] mailing lists 
> by 2006-08-17.
> 
> The file can be obtained via
> http://www.ietf.org/internet-drafts/draft-ietf-midcom-mib-08.txt
> 
> 
> _______________________________________________
> IETF-Announce mailing list
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> https://www1.ietf.org/mailman/listinfo/ietf-announce
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---

From: Pyda Srisuresh <[email-masked]>
Date: Sun, 27 Aug 2006 23:00:20 -0700 (PDT)

Dan,

Thank you for your detailed comments. Sorry for the delayed response. I was
away on vacation and just got back. Please see my responses below inline.

regards,
suresh

> message' instead of 'SNMP GetRequest PDU', etc. ?

[suresh] The objective of section 4.2 was essentially to indicate how the
MIDCOM transactions can be mapped to SNMP. I.e., make the description of 
MIDCOM transactions to SNMP mapping easy to underdtand. Terms like "SNMP get
message" and "SNMP put message" are simply easier for the reader to relate
while talking about transactions.

>    as, for example, the NAT MIB module [RFC4008].
[suresh] OK; with a minor tweak to your suggested text as follows.
s/"(NAT devices, firewall)"/"(NAT, Firewll)/

> a retrieval happens before the object is set for the first time? 
[suresh] Oops... Will change the text to read as follows.

When retrieved, the object returns the last set value. If
no value has been set, it returns the default value of notset(3).

> documents which are written with a protocol-independent orientation. 
[suresh] I will leave to Juergen or Martin to comment on this.

> the desired behavior, or did I mis-understand something? 

[suresh] Yes, I believe, that is the desired behaviour. 

Note, however, the DESCRIPTION for midcomRuleStorageType says that attempts to
set this object to permanent will always fail with an inconsistentValue error.
And, the default value for this object is volatile(2).

> these are examples rather than RECOMMENDations. 
[suresh] I am OK with listing the error strings as examples, rather than as
recommendations. I will leave to Juergen or Martin to further comment on this.

> only global. Same about transport protocol and other read-write objects.
[suresh] As I said earlier, attempts to set midcomRuleStorageType to permanent
will always fail with an inconsistentValue error.

> 8 . There is no DEFVAL for midcomRuleFlowDirection 
[suresh] Right, that was intentional.

> IANA considerations about this. 

[suresh] Well, nothing specific to MIDCOM MIB per se. IANA assigns IP protocol
numbers independently, right.
> notifications do provide any clue. 
[suresh] The DESCRIPTION for midcomConfigIfEnabled does say the following.

   Setting
   this object to false(2) immediately stops middlebox
   support at the indexed IP interface.  This implies that
   all policy rules that use NAT or firewall resources at
   the indexed IP interface are terminated immediately.
   In this case, The MIDCOM agent MUST send notifications
   to all MIDCOM clients that have access to one of the
   terminated rules.

As for the rule termination event, please refer section 7.9.

regards,
suresh

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