Re: [Netconf] IETF 101 SN Question 1: Proper designation of receiver
Martin Bjorklund <mbj@tail-f.com> Tue, 26 June 2018 18:42 UTC
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Date: Tue, 26 Jun 2018 20:42:40 +0200
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To: evoit@cisco.com
Cc: kwatsen@juniper.net, netconf@ietf.org, timjenki@cisco.com, alex@clemm.org
From: Martin Bjorklund <mbj@tail-f.com>
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Subject: Re: [Netconf] IETF 101 SN Question 1: Proper designation of receiver
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"Eric Voit (evoit)" <evoit@cisco.com> wrote: > > From: Martin Bjorklund, June 26, 2018 4:11 AM > > > > "Eric Voit (evoit)" <evoit@cisco.com> wrote: > > > > From: Kent Watsen, June 25, 2018 3:43 PM > > > > > > > > >> >> <kent-orig> Okay, glad to see that you embrace using > > > > >> >> ietf-netconf-server, rather than ietf-netconf-client. And > > > > >> >> I'll grant you that it's infinitely more likely that the > > > > >> >> ietf-netconf-server module would be implemented (i.e., the > > > > >> >> top-level /ncs:netconf-server container exists), more so than > > > > >> >> the ietf-netconf-client module would be implemented. The WG > > > > >> >> created the top-level /ncc:netconf- client container more for > > > > >> >> the sake of symmetry than for having a use-case for when it > > > > >> >> would be implemented. I think the question to ask is, is it > > > > >> possible that a device wants to use SN but doesn't *implement* > > > > >> ietf-netconf- server? > > > > >> >> > > > > >> >> <Eric> Yes, this will be possible. Reasons would include: > > > > >> >> alternative > > > > >> transports > > > > >> >> (COMI, UDP), HTTP2 configured subscriptions (which might use > > > > >> >> ietf-restconf- server), or no need for a publisher to include > > > > >> >> the configured subscriptions feature. > > > > >> >> > > > > >> >> <Kent> I should've be more specific: is it possible that a > > > > >> >> device would use netconf-notif (where your leafref is defined) > > > > >> >> but not implement > > > > >> ietf-netconf- > > > > >> >> server? Similarly, restconf-notif would presumably have a > > > > >> >> leafref to > > > > >> >> ietf- > > > > >> >> restconf-server, etc. > > > > >> > > > > > >> >Yes. Cases would include: > > > > >> >(a) platform doesn't support configured subscriptions > > > > >> >(b) vendor has not yet implemented ietf-netconf-server, and uses > > > > >> >something > > > > >> else. > > > > >> > > > > >> (a) is this a valid case? - I thought this conversion only > > > > >> regards configured subscriptions. No leafref or equivalent would > > > > >> be needed to support a dynamic subscription. Right? > > > > > > > > > > Correct. But your question was "can you use netconf-notif without > > > > > a leafref > > > > to...". > > > > > Needing both drafts is absolutely the case for dynamic > > > > > subscription support, and ietf-netconf-server would not be needed here. > > > > > > > > I read the above a few times, but I'm having a hard time > > > > understanding it. Can say it differently or provide an example? > > > > > > Dynamic subscriptions over NETCONF requires > > > draft-ietf-netconf-netconf-event-notifications. With these > > > deployments, there there is no call home, there is no configuration, > > > and there need be no ietf-netconf-server.yang leafref (or use of > > > ietf-netconf-server.yang grouping). > > > > > > > >> (b) this seems like a possibility, but then I think this make the > > > > >> case for why a leafref to the global *conf servers definitions > > > > >> won't always > > > > work. > > > > > > > > > > Agree that nothing here will always work. Deployments commonly > > > > > will have a heterogeneous mixture of model ecosystem models. > > > > > > > > > > This actually makes a *very* strong case for why the leafref > > > > > should be added as an augmentation from the *conf-server models. > > > > > That way leafref augmentations are explicitly tied to the actual > > > > > implementation of the > > > > model against which they refer. > > > > > > > > Not in the *conf-server models, the augments go into the *conf-notif > > > > models, I assume that is what you meant. > > > > > > My assertion is a good solution would be updating > > > ietf-netconf-server.yang per what is below. Note that an answer even > > > further below regarding the sharing of a single NETCONF session across > > > multiple subscriptions and typical RFC6241 protocol interactions is > > > assumed. But we could also insert your ietf-netconf-server.yang > > > grouping just as effectively where the leafref is seen. > > > > > > Anyway here are the following changes which would be made to > > > ietf-netconf-server.yang > > > > > > import ietf-subscribed-notifications { prefix sn; } > > > import ietf-netconf-subscribed-notifications { prefix nsn; } > > > > > > feature subscription-support { > > > description > > > "The 'subscription-support' feature indicates that the NETCONF server > > > supports configured subscriptions over call-home connections."; > > > reference > > > "RFC xxxx: Customized Subscriptions to a Publisher's Event Streams"; > > > } > > > > > > augment "/sn:subscriptions/sn:subscription/sn:receivers/sn:receiver" { > > > if-feature "subscription-support"; > > > when 'derived-from(../../../transport, "nsn:netconf")'; > > > description > > > "This augmentation allows NETCONF specific parameters to be exposed > > > for a receiver."; > > > leaf netconf-endpoint { > > > type leafref { > > > path "/ncs:netconf-server/ncs:call-home/ncs:netconf-client/ncs:name"; > > > } > > > description > > > "Remote client which need to initiate the NETCONF transport if an > > > existing NETCONF session from that client is not available."; > > > } > > > } > > > > > > With such a construct, it is impossible to add a leafref (or grouping) > > > within ietf-subscribed-notifications unless ietf-netconf-server.yang > > > exists. > > > > > > > >> This is why I > > > > >> was thinking before that your modules might themselves *use* the > > > > >> *conf- server-groupings (while pruning out unneeded parts, e.g., > > > > >> the "listen" subtree), so that it's independent of what the > > > > >> system has implemented at the global level. > > > > > > > > > > If you have 500 subscriptions, you then have to populate 500 > > > > > identical > > > > groupings. > > > > > > > > No, you have one grouping, with 500 > > > > /netconf-server/call-home/netconf-client > > > > instances. > > > > > > Yes. But I don't know why someone would voluntarily do add 500 > > > repeated elements to a configuration datastore. > > > > > > > > And yes this is possible. But it makes the part of me which > > > > > likes Normalized data quite uncomfortable. > > > > > > > > > > But as I said before, it the WG wants such redundancy, fine. > > > > > Either choice need not impact decisions as part of LC. > > > > > > > > I don't believe that is a WG-preference thing, so much as an outcome > > > > of the current design, which is that each receiver for each > > > > subscription has its own state-machine and protocol messages. There > > > > is no sharing; no two receives can use the same RFC 6241 NETCONF > > > > session, which effectively translates to each receiver having its > > > > own /netconf-server/call-home/netconf-client > > > > instance, > > > > right? > > > > > > This is incorrect. Protocol and state-machine messages have been > > > decoupled from the transport session. > > > > > > I am not sure why you think that subscriptions are unable to use a > > > common NETCONF session? Implementations of dynamic NETCONF > > > subscriptions have been doing this for years. Subscription > > > multiplexing of configured and dynamic subscriptions over a common > > > transport is a pre-requisite for solution scalability. > > > > I don't think muliplexing of configured and dynamic subscriptions over a single > > session is possible. > > > > If this is the intention of the current design, the document > > needs to explain how this is supposed to be done. > > What is your concern? Suppose a client connects to a server and starts a dynamic subscription. Can this session somehow be used for a configured subscription? I assume not. > > Multiplexing multiple configured subscriptions over a single transport session > > could be possible, but the document doesn't mention this. > > Again, if this is the intention, it needs to be properly described in the > > document. > > What is missing? The subscribed-notification draft section 2.5.1 > and Figure 9 describe how each receiver is pushed their own state > notifications. (I.e., the state machine is per-receiver. It is > not per-subscription, nor is it per-transport.) If there are two different subscriptions configured, each has its own list of receivers. Under which circumstances will the server decide to use a single transport session for these two different subscriptions? I can't see any text about this in the document. > > This said, "session sharing" can be acheived with the current design, as well as > > with the alternative design where the protocol is defined per receiver rather > > than per subscription. > > Agree. Any issues with NETCONF transport multiplexing of subscriptions should be independent of the receiver YANG model. > > > But it won't be interoperable unless it is described. > > Likely NETCONF specific concerns would land in the NETCONF-notif. I am happy to make any needed clarifications. I think you will need specific text in both subscribed-notifications and in the transport drafts, if this is what you want to support. /martin > > Eric > > > /martin >
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- [Netconf] IETF 101 SN Question 1: Proper designat… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Martin Bjorklund
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Kent Watsen
- Re: [Netconf] IETF 101 SN Question 1: Proper desi… Eric Voit (evoit)