[NGO] Re: Why NETCONF needs a data modeling language
Jon Saperia <saperia@jdscons.com> Sun, 02 December 2007 22:46 UTC
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From: Jon Saperia <saperia@jdscons.com>
Date: Sun, 02 Dec 2007 17:43:53 -0500
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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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Wrong order - people will push (not just the vendors for convenience) when there is something that makes a real difference. On Dec 2, 2007, at 3:19 PM, Balazs Lengyel wrote: > 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> >>> >>> > Thanks, /jon ---- Jon Saperia saperia@jdscons.com (mobil) 617-201-2655 (office) 978-461-0249
_______________________________________________ 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