[Apn] APN vs. Network Slicing

["Jeffrey (Zhaohui) Zhang" <[e-mail]>]

Hi Jim,

To follow up on your comments about APN vs. Slicing, here are some points that I did not have time to exchange during the BoF.

- While slicing does involve setting aside/up resources, that is the means to meet specific requirements for traffic delivery.
- Traffic delivered in network slices are identified by some identifiers so that network nodes knows how to forward them to meet the requirements. Combined with "slice aggregate" concept introduced in draft-bestbar-xxx drafts, fine granularity can be achieved down to flow level (vs. slice level).

In short, the goal of APN and slicing are the same (or slicing covers even more). Additionally, it is not that slicing is a use case of APN. It's the other way around - slicing does what APN want to do.

I could not get my one-page slide shared to better illustrate my point that APN problem domain/solution are already covered by IETF slicing, but let me post the text from that slide here. The sub-bullets are text quoted from the network slicing framework https://datatracker.ietf.org/doc/html/draft-ietf-teas-ietf-network-slices。

*       Ongoing IETF Network Slicing work already addresses the problem domain and solution
*       An IETF Network Slice provides the required connectivity between different entities in RAN and CN segments of an end-to-end network slice, with a specific performance commitment.
*        It is intended that IETF Network Slices can be created to meet specific requirements, typically expressed as bandwidth, latency, latency variation, and other desired or required characteristics.
*       An IETF Network Slice combines the connectivity resource requirements and associated network behaviors such as bandwidth, latency, jitter, and network functions with other resource behaviors such as compute and storage availability.
*       Term "Slice" refers to a set of characteristics and behaviors that separate one type of user-traffic from another.  IETF Network Slice assumes that an underlying network is capable of ... fulfilling all or some of SLOs to all of the traffic in the slice or to specific flows
*       Many approaches are currently being worked on to support IETF Network Slices in IP and MPLS networks with or without the use of Segment Routing.  Most of these approaches utilize a way of marking packets so that network nodes can apply specific routing and forwarding behaviors to packets that belong to different IETF Network Slices. Different mechanisms for marking packets have been proposed (including using MPLS labels and Segment Rouing segment IDs)
*       The realization can be achieved in a form of either physical or logical connectivity using VPNs, virtual networks (VNs), or a variety of tunneling technologies such as Segment Routing, MPLS, etc.
*       Slice Aggregate concept (similar to DiffServ Behavior Aggregate) in draft-bestbar is about identifying some or all traffic in a slice using opaque numbers and providing corresponding forwarding treatment
*       Forwarding/steering should be based on opaque numbers not structured APN IDs

Thanks.
Jeffrey




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