12/11/00Policy Framework WG - 49th IETF1 QDDIM-02 Issues Policy Framework WG 49th IETF Bob Moore -

12/11/00Policy Framework WG - 49th IETF2 QDDIM-02 Previously QDIM, the QoS Device Information Model In order to move the document forward, the scope was narrowed to DiffServ Thus QDDIM, the QoS DiffServ Device Information Model

12/11/00Policy Framework WG - 49th IETF3 Issue 1: Derivation of Schedulers Should the class PacketSchedulingService be derived –from ConditioningService, just as the classes for Classifiers, Meters, Markers, Droppers, and Queues are? –from ForwardingService, because a Scheduler is different in an important way from the other DiffServ elements?

12/11/00Policy Framework WG - 49th IETF4 Issue 1: Pictures Fwd Cond ClasMetMarkDropQSch Fwd Cond ClasMetMarkDropQSch

12/11/00Policy Framework WG - 49th IETF5 Issue 1: Discussion What would PacketSchedulingService inherit from ConditioningService? –Being a Conditioning Service -- aligns with the DiffServ Informal Model –Participates in NextService associations –Association with protocol endpoint -- people think of a Scheduler as the last Conditioning Service on an egress interface

12/11/00Policy Framework WG - 49th IETF6 Issue 1: Discussion Why should PacketSchedulingService not inherit from ConditioningService? –A Scheduler is in the control plane, not in the data plane; thus it doesn’t condition traffic (although it controls the conditioning of traffic)

12/11/00Policy Framework WG - 49th IETF7 Issue 2: Scheduling Disciplines Should specific scheduling disciplines be represented by –subclasses of the SchedulerUsed association? –subclasses of PacketSchedulingService?

12/11/00Policy Framework WG - 49th IETF8 Issue 2: Pictures Q Sched SchedulerUsed PrioritySchedulerUsed BoundedPrioritySchedulerUsed * * * 0..1 etc. Q Sched SchedulerUsed * 1 PriSchedBoundedPriSchedetc.

12/11/00Policy Framework WG - 49th IETF9 Issue 2: Multi-Discipline Scheduler Warning: Instance diagram Q1 Q2 Q3 Q4 Q5 Scheduler 1 Priority WRR Is this combination allowed or not?

12/11/00Policy Framework WG - 49th IETF10 Issue 2: Per-Queue Properties Q1 Q2 Q3 Scheduler 1 Priority Where to put the priority values (if not in the associations, then where)? Warning: Instance diagram

12/11/00Policy Framework WG - 49th IETF11 Issue 3: Algorithmic Droppers Currently in QDDIM HeadTailDropperSvc is a subclass of DropperService, but other subclasses of DropperService represent the drop algorithm, not the drop location The Informal Model is moving towards representing head / tail dropping solely by the relative placement of the queue and the dropper

12/11/00Policy Framework WG - 49th IETF12 Issue 3: Algorithmic Droppers There seem to be four (independent?) parameters that characterize a dropper: –Which queue to drop from –Where in that queue to drop from (head, tail, etc.) –Which queue or queues to monitor to make the drop decision (often, but not always, this is the same queue from which packets are dropped) –The parameterized algorithm for making the decision whether or not to drop a packet

12/11/00Policy Framework WG - 49th IETF13 Issue 3: Algorithmic Droppers So long as we don’t allow the sequence Q-->Dropper-->Q, the first two are handled by the sequence of Conditioning Elements Need a separate association for #3; in the MIB, diffServAlgDropQMeasure Subclass of DropperService, with additional properties, specifies a drop algorithm and its parameters

12/11/00Policy Framework WG - 49th IETF14 Issue 3: Algorithmic Droppers QDDIM also has a class DropThresholdCalculationService, which monitors a set of queues, and aggregates information about them into values that a Dropper can use in its drop algorithm Currently this service is not modeled in the Informal Model, the MIB, or the PIB Is this something that should be added to the three DiffServ documents?

12/11/00Policy Framework WG - 49th IETF15 Issue 4: Representing Filters Packet filtering clearly applies to more than DiffServ Currently have several ways to represent filters single-field generic (FilterEntry) single-field specific (examples in IPSP) multi-field specific (e.g., IP6TupleFilter) atoms (defined in QPIM) How much convergence do we need here?

12/11/00Policy Framework WG - 49th IETF16 Any Other Issues?