[NGO] Re: Why NETCONF needs a data modeling language
Balazs Lengyel <balazs.lengyel@ericsson.com> Sun, 02 December 2007 20:19 UTC
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Date: Sun, 02 Dec 2007 12:19:01 -0800
From: Balazs Lengyel <balazs.lengyel@ericsson.com>
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To: Jon Saperia <saperia@jdscons.com>
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Cc: yang@ietf.org, discuss@apps.ietf.org, 'NETCONF Goes On' <ngo@ietf.org>
Subject: [NGO] Re: Why NETCONF needs a data modeling language
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Hello, Naturally our aim is to develop standard NETCONF configuration models, and the more people use NETCONF the easier that will be. Balazs Jon Saperia wrote: > > Thanks > /jon > ---------------------- > Jon Saperia > TSP NM > (mobil) 617-201-2655 > (office) 978-461-0249 > saperia@jdscons.com <mailto:saperia@jdscons.com> > > > > On Dec 2, 2007, at 1:20 PM, Balazs Lengyel wrote: > >> Hello, >> >> Q1) Why does NETCONF need a DML at all? >> >> If we have an IETF standard DML for NETCONF, device vendors (like my >> company) will be much more comfortable, much more willing to adapt >> NETCONF itself. With a standard DML we would see a better chance at >> having available 3rd party or even freeware toolkits for NETCONF. > > Yes, but does that mean that we will begin to develop a standard > configuration objects for say, BGP or DiffServ that would work from one > vendor to the next? It would be nice to think so, that would really > help interoperability and should be the target of 'our' collective efforts. > /jon >> >> The above would be important even for a company which would not care >> about interoperability. >> >> Balazs >> >> David Harrington wrote: >>> >>> >>> >>>> Hi, >>>> >>>> There are a few questions that the IESG and others have asked, >>>> which I will try to address: >>>> >>>> Q1) Why does NETCONF need a DML at all? >>>> Q2) Why is NETCONF special? >>>> Q3) Why won't lots of other WGs want to define their own >>>> protocol-specific DMLs? >>>> Q4) Why isn't XSD or RelaxNG good enough? >>> I'll take a whack at answering the same questions. >>> A1) Why does NETCONF need a DML at all? >>> to promote vendor-neutral interoperable management. It is much easier >>> to develop standards when everybody uses the same >>> basic language to communicate; this "common language for shared >>> communication" is also reflected in the IETF decision to use English >>> text and ASCII documents. >>> This is not just about being able to standardize **device >>> management**; it is a basic step to permit the standardization of >>> **network management** and possibly **services management". The DML is >>> a basic building block. >>> A2) Why is NETCONF special? >>> It is and it isn't. Netconf is only one protocol used for network >>> management. It has some unique requirements, such as using a >>> document-based >>> approach and differentiating the data for config versus state and for >>> dealing with different time-defined contexts such as running and >>> startup configs. This differs from other network management protocols, >>> such as SNMP and syslog and ipfix, which use their own data formats, >>> and usually deal only with the currently-running config. Netconf is a >>> tool designed to meet the special requirements of configuration, and >>> the DML needs to support special features not found in other NM-DMLs. >>> Netconf is not special, in that any language used for network >>> management is likely to have certain common requirements. NM data >>> models are commonly used directly by humans, in their raw form, such >>> as when they troubleshoot problems using network sniffers. NM data >>> models are also commonly used by NMS applications that can handle the >>> translations into a more human-readable format. Designers of NM tools >>> (e.g., protocols and data models) thus need to pay close attention to >>> who will use the information, and to assume that the data will be used >>> both directly by humans and by applications. Operators have complained >>> strongly that OIDs are very hard to work with in raw form, yet >>> operators frequently need to deal with the raw form of the data. A3) >>> Why won't lots of other WGs want to define their own >>> protocol-specific DMLs? >>> To paraphrase a wise man from the SNMP community, when you fill a room >>> with protocol designers and ask for a solution to a problem, is it a >>> surprise when they recommend designing a new protocol? >>> The decision about whether to use an existing protocol/DML or develop >>> a new protocol/DML should be made after a careful analysis of the >>> requirements of the solution. SNMP was designed when CMIP was found to >>> not quite address the needs. The SMI was designed when ASN.1 was found >>> to not quite address the needs. XML was designed when other DMLs were >>> found to not quite address the needs. >>> The decision to explore an XML-based DML and to explore a C-like DML >>> follows years and years and years of debate over the requiremnts of >>> network management, and configuration in particular. If every WG >>> spends as much time analyzing the requirements that the >>> OPS area has spent considering this decision, it might be good for >>> ensuring no new protoocls are designed that are not really needed, but >>> the IETF would also grind to a halt, much as the OPS community has >>> done over our many years of debate. And the delay caused by our >>> debates has made IETF network management largely irrelevant to the >>> operator community (our customers). >>> As always, we need to be vigilant and determine whether enough thought >>> has been given to reuse of existing protocols. We also need to >>> consider the tradeoffs between new protocols and reusing existing >>> protocols in ways they were not designed to be used. >>> A4) Why isn't XSD or RelaxNG good enough? >>> As mentioned in A2, NM data models need to be both machine- and >>> human-readable. XSD is machine-readable, but it is a tough language >>> for humans. RelaxNG seems better. As discussed further in a different >>> email, Netconf will almost >>> certainly need a DML suited to its requirements, and if RelaxNG is >>> found to be human-friendly-enough, we would almost certainly still >>> need to select a subset and adapt it to meet configuration >>> requirements. So the benefit of using RelaxNG over a domain-specific >>> DML may be lost by using an adapted-subset of RelaxNG. >>> Most operators already understand languages like Perl and C and >>> Javascript, because they already need to write lots of scripts to >>> manage their networks. Most implementers of NM support in >>> internetworking devices work in C or a variant of C. It makes a lot of >>> sense to use a language with a C-like syntax for these people, rather >>> than forcing them to learn yet another language that was designed for >>> some other purpose. >>> [soap] >>> somebody commented that the designers of XSD and RelaxNG really >>> understand how to design DMLs, implying that the OPS community does >>> not. Many of the people involved in the ongoing DML discussions over >>> the years, and now, are MIB Doctors and operators and protocol >>> designers, and have had years of experience designing and working with >>> SMI and network management. They understand the requirements of a DML >>> for NM far more than the designers of XSD or RelaxNG, who were not >>> designing their DMLs for NM purposes. >>> [end soap] >>> David Harrington >>> dbharrington@comcast.net <mailto:dbharrington@comcast.net> >>> ietfdbh@comcast.net <mailto:ietfdbh@comcast.net> >> >> > _______________________________________________ NGO mailing list NGO@ietf.org https://www1.ietf.org/mailman/listinfo/ngo
- [NGO] Why NETCONF needs a data modeling language Andy Bierman
- [NGO] Re: Why NETCONF needs a data modeling langu… Juergen Schoenwaelder
- [NGO] Re: Why NETCONF needs a data modeling langu… Phil Shafer
- [NGO] Re: Why NETCONF needs a data modeling langu… Rohan Mahy
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Ladislav Lhotka
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Juergen Schoenwaelder
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Andy Bierman
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Ladislav Lhotka
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Balazs Lengyel
- RE: [NGO] Re: Why NETCONF needs a data modeling l… Romascanu, Dan (Dan)
- [NGO] Re: Why NETCONF needs a data modeling langu… Rohan Mahy
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Ladislav Lhotka
- Re: [NGO] Re: Why NETCONF needs a data modeling l… Ladislav Lhotka
- [NGO] Re: Why NETCONF needs a data modeling langu… Chris Cross
- [NGO] Re: Why NETCONF needs a data modeling langu… Phil Shafer
- [NGO] RE: [YANG] Re: Why NETCONF needs a data mod… David Harrington
- [NGO] Why NETCONF needs a data modeling language David Harrington
- [NGO] Re: Why NETCONF needs a data modeling langu… Martin Bjorklund
- [NGO] Re: Why NETCONF needs a data modeling langu… Andy Bierman
- [NGO] Re: Why NETCONF needs a data modeling langu… Balazs Lengyel
- [NGO] Re: Why NETCONF needs a data modeling langu… Jon Saperia
- [NGO] Re: Why NETCONF needs a data modeling langu… Balazs Lengyel
- [NGO] Re: Why NETCONF needs a data modeling langu… Jon Saperia