Re: [netconf] [yang-doctors] Yangdoctors last call review of draft-ietf-netconf-subscribed-notifications-21
Martin Bjorklund <mbj@tail-f.com> Fri, 25 January 2019 15:29 UTC
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Date: Fri, 25 Jan 2019 16:29:41 +0100
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To: evoit@cisco.com
Cc: andy@yumaworks.com, rrahman@cisco.com, alexander.clemm@huawei.com, yang-doctors@ietf.org, netconf@ietf.org, draft-ietf-netconf-subscribed-notifications.all@ietf.org
From: Martin Bjorklund <mbj@tail-f.com>
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Subject: Re: [netconf] [yang-doctors] Yangdoctors last call review of draft-ietf-netconf-subscribed-notifications-21
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"Eric Voit (evoit)" <evoit@cisco.com> wrote: > > From: Martin Bjorklund, January 25, 2019 3:40 AM > > > > "Eric Voit (evoit)" <evoit@cisco.com> wrote: > > > > "Eric Voit (evoit)" <evoit@cisco.com> wrote: > > > > > > "Eric Voit (evoit)" <evoit@cisco.com> wrote: > > > > > > > > From: Martin Bjorklund, January 24, 2019 9:40 AM > > > > > > > > > > > > > > > > "Eric Voit (evoit)" <evoit@cisco.com> wrote: > > > > > > > > > > From: Martin Bjorklund, January 24, 2019 8:17 AM > > > > [...] > > > > > > > > > > > > Thinking some more, what is supposed to happen if the > > > > > > > > > > client on the same session sends first an > > > > > > > > > > establish-subscription with dscp 42, and then another > > > > > > > > > > establish- > > subscription with dscp 10? > > > > > > > > > > > > > > > > > > This would be allowed. > > > > > > > > > > > > > > > > On linux at least this is a sockopt, i.e., the option > > > > > > > > applies to the socket, which means all packets on the > > > > > > > > session. So how is this supposed to be implemented if > > > > > > > > different messages on the session should have different dscp > > > > > > > > values? > > > > > > > > Or is the > > > > > > > > idea that you send the msg, flush all data from ssh/tls to > > > > > > > > tcp, then flush the tcp buffers (not that easy...)? > > > > > > > > > > > > > > > > Even if there's just one establish-subscription with a dscp > > > > > > > > value, since it applies to the session it means that all > > > > > > > > normal rpcs on this session will get the same dscp value. > > > > > > > > It is not clear that this is the intention? > > > > > > > > Did you miss these questions? > > > > > > With NETCONF, one DSCP will apply to single TCP session. So there is > > > no > > issue. > > > > The problem is if a client sends two establish-subscriptions with > > different > > values for dscp on the same session. Or even if the client sends one > > establish- > > subscription with som dscp value, then the dscp will be applied to all > > packets > > from other rpcs as well. > > > > ... and even worse, with SSH channels you can have multiple NETCONF > > session > > on the same TCP session, which means that the dscp value applies to > > all > > packets in all NETCONF sessions sharing the same TCP session. > > > > I don't know what the right thing to do is. Probably first agree that > > this is in > > fact a problem, then maybe simply document this somehow. > > I hadn't thought about multiple NETCONF SSH channels. I agree > something to guide developers is needed here. The easiest fix is to > recommend not supporting feature "dscp" with NETCONF. (It shouldn't > be absolutely prohibited as DSCP related RFC's such as RFC7657 embed > text like "a single DSCP should be used for all packets in a TCP > connection".) > > Here is the text I suggest is put into > draft-ietf-netconf-netconf-event-notifications, Section 5: > > "The feature "dscp" SHOULD NOT be supported over NETCONF. This will > avoid the potential for out-of-order packet delivery of the set of all > traffic within the TCP session." I think this is a bit too limiting. For configured subscriptions it can be perfectly fine, since the server can ensure that there's a single TCP session to the receiver in this case. (I know we don't support configured subscriptions at the moment). Perhaps we can say in the SN document: If a server that supports the "dscp" feature cannot guarantee that the only packets sent on an underlying transport session are from the subscription, then it should reject the subscription with a "dscp-unavailable" error. This will avoid the potential for out-of-order packet delivery of the set of all traffic within the TCP session. I think such text belongs to the SN document, since it may apply to other transports than just NETCONF. /martin > With this text, a RESTCONF publisher can support the feature dscp. > And if someone attempts to use dscp with a NETCONF subscription to the > same publisher, the error "dscp-unavailable" can be sent. > > Eric > > > ... > > /martin >
- [Netconf] Yangdoctors last call review of draft-i… Andy Bierman
- Re: [Netconf] Yangdoctors last call review of dra… Eric Voit (evoit)
- Re: [Netconf] Yangdoctors last call review of dra… Andy Bierman
- Re: [netconf] Yangdoctors last call review of dra… Eric Voit (evoit)
- Re: [netconf] Yangdoctors last call review of dra… Mehmet Ersue
- Re: [netconf] Yangdoctors last call review of dra… Andy Bierman
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Andy Bierman
- Re: [netconf] Yangdoctors last call review of dra… Andy Bierman
- Re: [netconf] Yangdoctors last call review of dra… Eric Voit (evoit)
- Re: [netconf] Yangdoctors last call review of dra… Andy Bierman
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Andy Bierman
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Andy Bierman
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Andy Bierman
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Martin Bjorklund
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Per Hedeland
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Per Hedeland
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)
- Re: [netconf] [yang-doctors] Yangdoctors last cal… Eric Voit (evoit)