Re: [Idr] BGP Yang modules and core features
"Susan Hares" <shares@ndzh.com> Wed, 11 February 2015 00:16 UTC
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From: Susan Hares <shares@ndzh.com>
To: 'Jeffrey Haas' <jhaas@pfrc.org>, idr@ietf.org
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Date: Tue, 10 Feb 2015 19:15:41 -0500
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Subject: Re: [Idr] BGP Yang modules and core features
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Jeff: Thank you for this great response for the call to input. Your message saved me from writing the second email message on "if-feature". Did we really have heated debate - I thought it was a "lively debate" (smile)? <chair hat on> First would be good to get input from those who have implemented if-features on impact on setting configs or the dynamic nature (i2rs). Second, if your BGP implementation does not support the BGP Yang modules covered by both Yang drafts - would you contact me (off-list is fine): (bgp-yang) draft-zhdankin-idr-bgp-cfg-00 (oc-b gp) OpenConfig RFC4271 BGP Protocol Specification [bgp-yang & oc-bgp] RFC1997 BGP Community Attribute [bgp-yang & oc-bgp] RFC4456 BGP Route Reflection [bgp-yang & oc-bgp] RFC4760 BGP Multiprotocol Specification [bgp-yang & oc-bgp] RFC3065 Autonomous System Confederations for BGP [bgp-yang & oc-bgp] RFC2439 BGP Route Flap Dampening [bgp-yang & oc-bgp] RFC 4724 BGP Graceful Restart [bgp-yang & oc-bgp] RFC 6811 BGP Origin Validation [bgp-yang] Jeff raised the issue on the call that some groups of BGP applications may not support these BGP functions. The IDR chairs would like to hear from users or implementers. IMHU - (in my humble understanding) most open source implementations support all but RFC6811. <chair hat off> <Individual contributors hat on> I think the If-features can be useful for allowing a set of BGP Yang defined, and allowing nodes/implementations to signal what BGP support the note has functioning. If most implementations support these base features, then including this in a base yang modules is helpful to iplementors. <individual contributors hat off> Sue Hares -----Original Message----- From: Idr [mailto:idr-bounces@ietf.org] On Behalf Of Jeffrey Haas Sent: Tuesday, February 10, 2015 6:29 PM To: idr@ietf.org Subject: [Idr] BGP Yang modules and core features IDR, As a bit of history, I'm the editor/author on the existing BGP MIBs. The BGP MIBv2 work stalled out due to no one actually taking their enterprise implementation and normalizing it with the published draft, leaving it in limbo. During the MIBv2 work, one detail that churned the modeling work was the necessary "core protocol" details to include in the MIB. The original goal was to pick some common core BGP features such as route reflection, confederations, etc. and include them. However, it later occurred that if implementations did not support these common, but core features that they would not be able to implement the MIB. This lead to an effort to restructure the MIB to include these features as optional extension MIBs. Eventually, that work was abandoned as simply making things too complex. In my opinion, SNMP MIBs are awful for this type of modeling and I'm thrilled that Yang has become a useful language in the IETF. Why bring up the past? IDR has recently hosted two interims covering proposed BGP Yang modules: https://tools.ietf.org/html/draft-zhdankin-idr-bgp-cfg-00 https://tools.ietf.org/html/draft-shaikh-idr-bgp-model-00 Discussion on the drafts was good. IMO, there are issues in each that need some resolution. One issue in particular generated a bit of heated discussion during the most recent interim and I thought it worth requesting input from the broader Working Group. The two models have slightly different goals: zhdankin is intended to be a bit more of a complete model to serve as a basis for an IETF IDR model. shaikh is intentionally covering a restricted but common subset of BGP functionality in the networks of the authors. Both potentially offer the long-term option to be extended for greater completeness; Yang is very nice about allowing extension modules. The question I'm raising is the core features present in the modules in the context of IDR eventually adopting a module as "the IETF BGP module". In the forms both of these drafts are in, there is no optional configuration. As an example, -shaikh includes a ipv4-l3vpn-unicast container. If you were communicating with a netconf server implementing the module as specified, your software would believe that l3vpn-unicast is supported. Unlike SNMP, we're not stuck with the need for a lot of tricks to determine if a feature that is present in the model is available on the device or not. The "if-feature" clause in Yang (RFC 6020, sec 7.18.2) permits the module to make some of the content conditional based on whether a management implementation supports that feature or not. (It is advertised in the netconf hello statement; netconf RFC 6241, section 8.1.) Support for various address family (AFI/SAFI) configuration and operational state are obvious targets to make optional. "Core" features such as route reflection, confederations, communities? This is a much harder argument to make than it was when I began the BGP MIBv2 work. Even so, anything not tagged with if-feature becomes effectively a "mandatory to implement" component for the management plane. Certainly you could not implement it, netconf would return an appropriate commit error or failure on <get> for operational state that wasn't supported. However, that'd be inelegant at best. It would be good if the WG examines these candiate Yang modules and consider what they'd want as optional features. -- Jeff _______________________________________________ Idr mailing list Idr@ietf.org https://www.ietf.org/mailman/listinfo/idr
- [Idr] BGP Yang modules and core features Jeffrey Haas
- Re: [Idr] BGP Yang modules and core features Susan Hares