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Re: [ANCP] Comments on draft-ietf-ancp-framework-05.txt



Hi Francois,

Why would on-path CAC signaling query the NAS?  Since it is on-path, it 
is already on the NAS, so it will never query the NAS?

regards,
Stefaan


Francois Le Faucheur IMAP wrote:

> Hello,
> 
> Please find below a few comments/suggestions on framework-05.
> 
> Francois
> 
> 
> * under section 3.4.2:  first bullet.
> The following text has been added:
>       "The NAS may locally maintain available "video"
>        bandwidth on the Access Loop, and perform video bandwidth
>        accounting for the Access Loop.  Upon receiving an Admission
>        Request from the AN, the NAS can check available "video"  
> bandwidth
>        before admitting or denying the multicast flow.  In the process,
>        the NAS may communicate with the Policy Server.  For unicast  
> video
>        services such as Video on Demand (VoD), the Policy Server may  
> also
>        query the NAS, so that it can perform admission control for the
>        unicast flow, and update the available video bandwidth maintained
>        by the NAS.
> "
> Could we make this slightly more generic and replace the last  
> sentence with something like:
> "For unicast video services such as Video on Demand (VoD), the NAS  
> may also be  queried (by a Policy Server or via on-path CAC  
> signaling), so that it can perform admission control for the unicast  
> flow, and update the available video bandwidth maintained by the NAS."
> 
> * section 3.4.2: 2nd bullet.
> Similarly could we replace:
> "For unicast video services the policy server may query the NAS to  
> perform admission control for the unicast flow, and update the  
> available video bandwidth maintained by the NAS."
> by
> "For unicast video services the NAS may be queried (by a policy  
> server or via on-path CAC signaling) to perform admission control for  
> the unicast flow, and update the available video bandwidth maintained  
> by the NAS."
> 
> 
> * section 4.7.6
> The last requirement in the section is intended to reflect the  
> "Spontaneous Admission Response" functionality described in section  
> 3.4.4.
> As agreed, one scenario has been added to section 3.4.4 (ie where the  
> NAS is made aware of Join/Leave by other means than ANCP), and this  
> scenario needs to be reflected in section 4.7.6. I'd suggest adding  
> something like:
> "   o  Upon receiving an Admission Response from the NAS indicating  
> that replication of a multicast flow is to start or stop on a given  
> access port of the AN, the AN must enforce this decision whether a  
> corresponding Admission Request was issued earlier by the AN or not.
> "
> 
> * section 4.7.6:
> replace:
> "the AN should support receiving ANCP messages from the NAS  
> containing conditional access information of multiple multicast flows"
> by
> "the AN should support receiving ANCP messages from the NAS  
> containing conditional/admission access information of multiple  
> multicast flows"
> 
> * section 4.7.6
> There is one requirement stating that
> "the AN should support receiving ANCP messages from the NAS  
> containing conditional access information of multiple multicast flows."
> The details of such mechanism is largely left to the protocol design  
> team, which is fine.
> But it may be useful to identify one additional associated  
> requirement on AN, allowing AN to tell NAS that there is no longer  
> any multicast flows joined (within the admitted set of flows) so the  
> corresponding bandwidth can be freed up (where CAC is performed).  
> This could read :
> "   o  after receiving ANCP messages from the NAS containing  
> conditional access information of a set of multicast flows, the AN  
> should support using ANCP to notify the NAS when there is no longer  
> any multicast flows from that set joined for a configurable time-out  
> period."
> 
> 
> *section 4.8.6:
> replace:
> "the NAS should support sending an Admission Response message  
> containing conditional access information of multiple multicast flows"
> by
> "the NAS should support sending an Admission Response message  
> containing conditional/admission access information of multiple  
> multicast flows"
> 
> 
> * section 4.8.6:
> there needs to be a requirement here also for spontaneous admission  
> response. I would propose:
> "   o  the NAS may support using ANCP to indicate to the AN that  
> replication of a multicast flow is to start or stop on a given access  
> port of the AN, without having received a corresponding Admission  
> Request earlier from the AN.
> "
> 
> *section 4.8.6
> I believe the WG agreed that the following text needs to be confirmed  
> on the list before it could stay in framework doc.
> "
>     o  The ANCP MUST allow the NAS, when replying to an AN request, to
>        OPTIONALLY convey information on multiple multicast flows sharing
>        the same conditional access rules.  This allows the AN to take
>        autonomous decisions for these flows later on.
> "
> 
> 
> editorial suggestions:
> ================
> * Section 3.4:
> Current text:
> "The NAS can perform conditional
>     access and multicast admission control on IGMP joins, and create
>     replication state in the AN if the flow is admitted by the NAS."
> Change:
> replace "IGMP joins" by "joins"
> Justification:
> Joins/leaves may be communicated via IGMP or via some other means.
> 
> * section 3.4.2.2
> replace:
> "Otherwise, the Access Node would have to query the NAS for Multicast  
> Admission Control"
> by:
> "Otherwise, the Access Node would have to query the NAS for Multicast  
> Admission Control (as per Grey List behavior)"
> 
> 
> Typos:
> =====
> * section 3.4.2:
> s/as well as for other a set of multicast flows/as well as for a set  
> of multicast flows/
> * in a few places: replace "lateron" by "later on"
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