Metadata Considerations draft-rijsman-sfc-metadata-considerations-00 Service Function Chaining Working Group IETF 89 - London - March 2014 Authors: Bruno Rijsman, Jerome Moisand Presenter: Ross Callon

2 Presented at IETF London 2014 SERVICE FUNCTION CHAINING ABSTRACTIONS IETF SERVICE FUNCTION CHAINING (SFC) WORKGROUP SFN SFI SFN SFI SFN SFI SFN SFI SFN SF SC Service Classifier Service Function Service Function Node Service Function Instance SFI SC Service Chain SP Service Path SPS Service Path Segment

3 Presented at IETF London 2014 WHAT IS METADATA? Metadata is "data about data" SFN SFI SFN SFI SFN SFI SC data Data in flow 1 metadata Metadata about flow 1 metadata Metadata about flow 2 Data in flow 2

4 Presented at IETF London 2014 METADATA USE CASE 1: SUBSCRIBER-AWARENESS CONTEXTUAL INFORMATION WHICH IS NOT LOCALLY AVAILABLE SFN SFI SFN SFI data Data Metadata data Per subscriber accounting and billing accounting-id PGW PCRF SC

5 Presented at IETF London 2014 METADATA USE CASE 2: APPLICATION-AWARENESS AVOID REPETITION OF EXPENSIVE OPERATION (E.G. DPI) SFN SFI data Data Metadata data Deep Packet Inspection (DPI) application-id SFN SFI Application-aware services No need to re-apply DPI

6 Presented at IETF London 2014 METADATA USE CASE 3: FINE-GRAINED POLICIES SUPPORT FINE-GRAINED POLICIES WITHOUT NEEDING MANY CHAINS SFN SFI SFN SFI data Data Metadata data One chain with fine-grained policies bandwidth-cap = 34 Mbps BNG RADIUS SC data Data Metadata data bandwidth-cap = 17 Mbps

7 Presented at IETF London 2014 METADATA SIGNALING - ARCHITECTURAL OPTIONS SFN SFI SFN SFI metadatadata Option 1: In-band marking Attach metadata to each packet SFN SFI SFN SFI data GET / HTTP/1.1 Host: Connection: keep-alive Cache-Control: max-age=0 Accept: text/html,application/xhtml+xml User-Agent: Mozilla/5.0 (Windows NT 6.1) Accept-Encoding: gzip,deflate Accept-Language: en-US,en;q=0.8 Metadata-Subscriber-ID: Metadata-Session-ID: HTTP Request metadata Option 2: Application Layer Headers E.g. HTTP extension headers

8 Presented at IETF London 2014 METADATA SIGNALING - ARCHITECTURAL OPTIONS SFN SFI SFN SFI data Data plane data plane control plane data plane control plane Control plane metadata Option 3: Congruent Out-of-Band Signaling Option 4: Non-Congruent Out-of-Band Signaling SFN SFI SFN SFI data Control Plane: Metadata Signaling metadata

9 Presented at IETF London 2014 METADATA SIGNALING - ARCHITECTURAL OPTIONS Option 5: Hybrid: In-Band Session-ID + Out-of-Band Signaling session-iddata SFN SFI SFN SFI data plane control plane data plane control plane Data plane Control plane session-id  metadata mapping

10 Presented at IETF London 2014 METADATA CHALLENGES Support for metadata-unaware service function Preserving metadata through metadata-unaware service functions Metadata encoding (fixed length versus TLV) Availability and performance of the control plane Synchronization between the control plane and the data plane Distributing metadata only to interested service functions Associating data plane flow with control plane signaling Layering considerations (separate path layer and service layer) Load balancing and symmetry High availability Geographic dispersion Multiple sources of metadata Extensibility

11 Presented at IETF London 2014 CONCLUSIONS Need standardization for multi-vendor interoperability Multiple approaches  In-band marking  Out-of-band signaling (congruent or non-congruent)  Hybrid approach Many challenges with each approach No single approach is obvious winner  Different approaches for different use cases?  Hybrid approach good match for mobile and fixed broadband Keep service path signaling and metadata signaling separate  Separate layers, separate headers, separate protocols  Don't need to be standardized at the same time