JMP> RE: IPP> SNMPv3 unsuited for IPP/JMP Notifications
"Turner, Randy" <rturner@sharplabs.com> Tue, 17 March 1998 18:28 UTC
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From: "Turner, Randy" <rturner@sharplabs.com>
To: "'imcdonal@eso.mc.xerox.com'" <imcdonal@eso.mc.xerox.com>, Joe_Filion@mc.xerox.com, ipp@pwg.org, jmp@pwg.org
Subject: JMP> RE: IPP> SNMPv3 unsuited for IPP/JMP Notifications
Date: Tue, 17 Mar 1998 10:23:01 -0800
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I am not sure what the dissenting opinion is, whether SNMPv3 is not the correct solution? Or, is the proposed notification MIB not the right solution? If SNMP is the wrong solution, then any SNMP-accessed MIB would be the wrong solution, including the JAM MIB. I will try and address the concerns outlined below, with matching numbers. 1) Scopes of interest are still supported by OID subtree specifications; it's the intended notification recipients that are identified and matched by the UTF-8 tag. 2) Registration lifetimes would be a good idea. It's quite possible for an IPP MIB to augment the notification table with objects that represent registration lifetimes. No need to throw the baby out with the bath water on this one. Since it is an explicit augmentation, the indices would be the same. 3) Indices that appear as SnmpAdminString types are labeled as NOT-ACCESSIBLE, so they should not appear in the response packet of a GET, or GET-BULK. 4) I'm not sure if a brute force search would be required or not (yet). It appears from reading the RFC that this might be the case and I understand how this conclusion could be made. However, I'm not sure that duplicate registrations could be identified solely on the basis of "transport" and "transport-address" matching. This particular scenario would require more study. 5) This rationale does not exist for SNMPv3. This held true only for V2 (and derivatives). All the text about "dual-role entities" from V2 has been removed from the V3 doc set. The V3 specs now generically identify "notification senders" and "notification recipients". The idea of specific functionality being reserved for a "mid-level" manager entity no longer exists. Implementors are free to instrument whatever feature they need, depending upon the type of management (or managed) entity is being constructed. 6) Again, this idea is a V2 idea, the restrictions on "how" a feature is used has been removed from the V3 specifications. See #5 above. Also, I have it on good authority from Jeff Case at SNMP Research, that the effort required to take the V1 trap code base and move it to V3 trap/inform is no great task. A lot of code reuse is possible. Also, V3 informs are as reliable as any other notification mechanism. 7) Again, I have it on first hand communication from Bob Stewart(Cisco), Jeff Case and David Levi(SNMP Research) that their "intent" was never to disallow the type of functionality I have proposed. Rather, it seems like a prudent reuse of all vendors' existing agent code base. This reuse of technology (both in design and existing code) is what I am trying to take advantage of. Given the speed at which SNMPv3 is being adopted, I feel like a lot of vendors are going to want to implement V3 agents anyway. Also, after looking at Ira's proposal for the JAM MIB, there are some ideas present in the JAM MIB that were not included in the standard notification/target MIBs specified in RFC 2273. I think we should include these ideas in whatever we come up with. I don't think we should completely reinvent the wheel here, rather, I think we should come up with a suitable set of additional (non-overlapping) notification features and AUGMENT the standard set. This is because, for a lot of reasons, I think vendors will eventually have to support them anyway to be "V3 compliant" at some point in the future. By the way, I have no SNMP religious affiliation, just a desire to reuse technology. If we find out that our requirements exceed the boundaries of what SNMPv3 and related technology can deliver, then I would be just as happy to pursue another path. But I think we need to study this stuff a little more before taking any radical direction change. Randy -----Original Message----- From: imcdonal@eso.mc.xerox.com [SMTP:imcdonal@eso.mc.xerox.com] Sent: Sunday, March 15, 1998 4:35 PM To: Joe_Filion@mc.xerox.com; ipp@pwg.org; jmp@pwg.org Subject: IPP> SNMPv3 unsuited for IPP/JMP Notifications Copies To: ipp@pwg.org jmp_pwg.org Hi folks, Sunday (15 March 1998) Extracted below (with line numbers) is summary information from the five SNMPv3 documents (RFC 2271 to RFC 2275, January 1998). As Randy Turner has argued, it IS possible to use a small subset (Target and Notification MIBs in RFC 2273) of the SNMPv3 MIB modules (there are a total of 7 SNMPv3 MIB modules) to achieve a simple (security-free) SNMP trap registration mechanism (see the 'snmpNotifyBasicCompliance' declaration at line 2773 of RFC 2273). But, the functionality provided is INFERIOR in important ways to that provided by the JAM (Job Async Monitor) MIB that Joe Filion and I posted on Wednesday (4 March 1998) or to my informal understanding of the IBM method presented by Harry Lewis during last week's PWG monthly meeting in Austin, TX. 1) The JAM MIB and Historic SNMP Party MIB (RFC 1447) support scope (traps of 'interest') specified as object identifier subtrees. The SNMPv3 Target/Notification MIBs support scope only by short (32 character) UTF-8 tags, which are NOT standardized by SNMPv3 and (due to their length) are NOT amenable to standardization. 2) The JAM MIB supports automatic trap deregistration specified as 'DateAndTime'. The SNMPv3 Target/Notification MIBs do NOT support automatic trap deregistration at all! 3) The JAM MIB supports simple integer indices for all 'read-create' object groups (written by a remote client). The SNMPv3 Target/Notification MIBs support indices ONLY as (32 character) UTF-8 'SnmpAdminString' values, seriously restricting the number of SNMP objects which can be transferred in a single packet. Since SNMP runs over UDP (in the Internet suite) and there is no 'chunking' for SNMP requests, this limitation is significant! 4) The JAM MIB supports a 'read-only' lookup table (maintained by the SNMP agent on the device) which provides direct lookup from SNMP transport domain and transport address to a client (target) trap registration entry (to avoid duplicate registrations). But, the SNMPv3 Target/Notification MIBs support only brute force (ie, read the entire Target table) for this important functionality! 5) The JAM MIB scales well to a very large number of (end-user) trap client (target) registrations. But, the SNMPv3 Target/Notification MIBs do not scale well. They are intended ONLY for use by network management stations! 6) Randy has suggested that SNMPv2/SNMPv3 'Inform' requests/responses could be used for (questionably) 'reliable' event notification. But, 'Inform' is intended by the SNMPv3 developers to be used ONLY for reporting up a hierarchy of network management stations! Also, 'Inform' is not defined in SNMPv1, so the huge installed base of SNMP agents which (almost exclusively) speak SNMPv1 cannot use 'Inform'. 7) Lastly, as SNMP agent toolkits become available from software tool vendors, any 'local' use of SNMPv3 Target/Notification MIBs by the printer industry vendors will inevitably conflict with the very different intent of the SNMPv3 developers. Recall why the Job Mon MIB is a PWG standard and NOT an IETF standard! As I hope most of you know, I'm dedicated to the use of standards where available and applicable. But the SNMPv3 MIBs were never intended to be used by many clients. They simply aren't appropriate to the problem of trap registration for PWG Job Mon MIB and IETF/PWG Printer MIB traps. Cheers, - Ira McDonald (High North, outside consultant at Xerox) ------------------------------------------------------------------------ **** SNMPv3 Documents **** rfc2271.txt: Architecture for Describing SNMP Management Frameworks - 38-44: This document describes an architecture for describing SNMP Management Frameworks. The architecture is designed to be modular to allow the evolution of the SNMP protocol standards over time. The major portions of the architecture are an SNMP engine containing a Message Processing Subsystem, a Security Subsystem and an Access Control Subsystem, and possibly multiple SNMP applications which provide specific functional processing of management data. - 1913: SNMP-FRAMEWORK-MIB DEFINITIONS ::= BEGIN - 2420: snmpFrameworkMIBCompliance MODULE-COMPLIANCE rfc2272.txt: Message Processing and Dispatching for SNMP - 41-46: This document describes the Message Processing and Dispatching for SNMP messages within the SNMP architecture [RFC2271]. It defines the procedures for dispatching potentially multiple versions of SNMP messages to the proper SNMP Message Processing Models, and for dispatching PDUs to SNMP applications. This document also describes one Message Processing Model - the SNMPv3 Message Processing Model. - 810: SNMP-MPD-MIB DEFINITIONS ::= BEGIN - 936: snmpMPDCompliance MODULE-COMPLIANCE - 976: SNMPv3MessageSyntax DEFINITIONS IMPLICIT TAGS ::= BEGIN rfc2273.txt: SNMPv3 Applications - 37-44: This memo describes five types of SNMP applications which make use of an SNMP engine as described in [RFC2271]. The types of application described are Command Generators, Command Responders, Notification Originators, Notification Receivers, and Proxy Forwarders. This memo also defines MIB modules for specifying targets of management operations, for notification filtering, and for proxy forwarding. - 1561: SNMP-TARGET-MIB DEFINITIONS ::= BEGIN - 2209: snmpTargetCommandResponderCompliance MODULE-COMPLIANCE - 2305: SNMP-NOTIFICATION-MIB DEFINITIONS ::= BEGIN - 2773: snmpNotifyBasicCompliance MODULE-COMPLIANCE - 2881: snmpNotifyBasicFiltersCompliance MODULE-COMPLIANCE - 2894: snmpNotifyFullCompliance MODULE-COMPLIANCE - 2960: SNMP-PROXY-MIB DEFINITIONS ::= BEGIN - 3242: snmpProxyCompliance MODULE-COMPLIANCE rfc2274.txt: User-based Security Model (USM) for SNMPv3 - 37-41: This document describes the User-based Security Model (USM) for SNMP version 3 for use in the SNMP architecture [RFC2271]. It defines the Elements of Procedure for providing SNMP message level security. This document also includes a MIB for remotely monitoring/managing the configuration parameters for this Security Model. - 861: USMSecurityParametersSyntax DEFINITIONS IMPLICIT TAGS ::= BEGIN - 1701: SNMP-USER-BASED-SM-MIB DEFINITIONS ::= BEGIN - 2439: usmMIBCompliance MODULE-COMPLIANCE rfc2275.txt: View-based Access Control Model (VACM) for SNMPv3 - 38-42: This document describes the View-based Access Control Model for use in the SNMP architecture [RFC2271]. It defines the Elements of Procedure for controlling access to management information. This document also includes a MIB for remotely managing the configuration parameters for the View-based Access Control Model. - 541: SNMP-VIEW-BASED-ACM-MIB DEFINITIONS ::= BEGIN - 1356: vacmMIBCompliance MODULE-COMPLIANCE ------------------------------------------------------------------------
- JMP> RE: IPP> SNMPv3 unsuited for IPP/JMP Notific… Turner, Randy