This is English version with additional slides and updated diagrams presented at Network Programmability Study #6 held on 29th Sept. ネットワークプログラマビリティ勉強会#6 で発表したスライドの英語バージョン。 スライド追加＆図などアップデートしてあります。 http://network-programmability.connpass.com/event/19603/

1. “Service Chaining”
- Overview as of 2015/10/05 -
Service Chaining ~ Overview as of 2015/10/05
Kentaro Ebisawa | Twitter: @ebiken
1

2. • Objective of this document is to gather “Service Chaining” related information for below
purposes.
• Quickly go over current state of Service Chaining.
• Reviewed as reference to documents, architecture diagrams and my current thoughts.
• “Service Chaining” is a technology area still rapidly evolving.
• Many discussions about architectural design are ongoing.
• Standardization of the reference architectures and protocols are still not finalized and could
change anytime. Refer to the original documents for the latest updates.
• Feedback is really appreciated.
• Opinions mentioned in this document is as of today and could change in future after more input.
(maybe by input from you :-)
• Information in this document could be not accurate as I wanted to be.
• Pointing out any mistakes, different thoughts or additional information are welcomed.
• Contact ebiken[at]gmail.com or twitter: @ebiken for any inputs and discussions.
Service Chaining ~ Overview as of 2015/10/05 2
about this slide deck

3. What is Service Chaining?
Service Chaining
Service Chaining ~ Overview as of 2015/10/05 3

4. What is Service Chaining?
Service Chaining
Steering of traffic flows through an ordered list of service functions.
Objective is to add elasticity by decupling it from network topology,
and achieve rapid deployment and glandular traffic steering.
Service Functions (Service Enablers)
A function that is responsible for specific treatment of received packets.
A service function can act at various layers of a protocol stack.
e.g., at the network layer or other OSI layers. (from RFC7498)
(ex: NAT, antimalware, parental control, DDoS protection, load balancer etc.)
Service Chaining ~ Overview as of 2015/10/05 4

5. Where discussions are happening?
Service Chaining
Service Chaining ~ Overview as of 2015/10/05 5

6. Where discussions are happening? 3GPP | IETF | ONF
3GPP
TR 23.718: Architecture Enhancement for Flexible Mobile Service Steering
http://www.3gpp.org/DynaReport/23718.htm
• Enhancements required for 3GPP systems to provide flexible mobile
service steering policies are discussed in the document.
• Topology and steering of flow among service functions (anything inside
SGi-LAN) are Out of Scope and expected to be implemented by using effort
of other Standardization Organization. (ex: IETF, ONF)
• Two Key Issues are discussed in the document.
• Key Issue 1: Interface for provisioning of traffic steering policy.
• Key Issue 2: Semantics of traffic steering policy.
Service Chaining ~ Overview as of 2015/10/05 6

7. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 7
Overview of LTE network
• eNB : enhanced NodeB, radio access part of the LTE system
• S-GW : Serving Gateway, primary function is user plane mobility
• P-GW : Packet Gateway, actual service creation point, terminates 3GPP
mobile network, interface to Packet Data Networks (PDN)
• HSS : Home Subscriber Server (control plane element)
• MME : Mobility Management Entity (control plane element)
• PCRF : Policy and Charging Rule Function
• PCEF : Policy and Charging Enforcement Function
• SGi : Egress termination point of the mobile network. The internal data
structure not standardized by 3GPP.
• TDF: Traffic Detection Function
• SCTCF: Service Chain Traffic Controller Function
E-UTRAN
EPC
SGi-LAN
eNodeB
UE: User equipment (ex: tablets or smartphones)
MME S-GW
HSS
PCRF
P-GW
PCEF
Gx
SGi
Sd
St
Referenced from draft-ietf-sfc-use-case-mobility-04
SGi
SCTCF
Service Functions
Forwarding Entities
ClassifiersTDF
(Evolved Packet Core)
External
Network

8. Where discussions are happening? 3GPP | IETF | ONF
Key Issue 1: Interface for provisioning of traffic steering policy
4 solutions are discussed for Key Issue 1
Service Chaining ~ Overview as of 2015/10/05 8
Solution
Interface and entity enhanced to signal the policy
and mark packets for steering traffic.
1.1
Leveraging of the existing PCC
framework with Sd interface
Sd interface and PCRF, TDF
1.2
Leveraging of the existing PCC
framework with Gx interface
Gx interface and PCRF, PCEF/PGW
1.3 Dual-Classifier Solution
Introducing TCFd, which is TCF for down stream
traffic. (In addition to Solution 1.1, 1.2)
1.4 Service steering policy interface
Introducing St interface and SCTCF(*) residing in
SGi-LAN. (In addition to Solution 1.1, 1.2, 1.3)
(*) SCTCF: Service Chain Traffic Controller Function

9. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 9
Key Issue 1: Interface for provisioning of traffic steering policy
1.1 Leveraging of the existing PCC framework with Sd interface
TR 23.718: Architecture Enhancement for Flexible Mobile Service Steering
http://www.3gpp.org/DynaReport/23718.htm

10. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 10
Key Issue 1: Interface for provisioning of traffic steering policy
1.2 Leveraging of the existing PCC framework with Gx interface
TR 23.718: Architecture Enhancement for Flexible Mobile Service Steering
http://www.3gpp.org/DynaReport/23718.htm

11. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 11
Key Issue 1: Interface for provisioning of traffic steering policy
1.3 Dual-Classifier Solution
TR 23.718: Architecture Enhancement for Flexible Mobile Service Steering
http://www.3gpp.org/DynaReport/23718.htm

12. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 12
Key Issue 1: Interface for provisioning of traffic steering policy
1.4 Service steering policy interface
TR 23.718: Architecture Enhancement for Flexible Mobile Service Steering
http://www.3gpp.org/DynaReport/23718.htm

13. Where discussions are happening? 3GPP | IETF | ONF
Key Issue 2: Semantics of traffic steering policy
Description of information exchanged to achieve traffic steering
• Traffic Steering Rule (TSR)
• Identifies the service functions traffic needs to be steered for a given IP/subscriber
session.
• Components of TSR:
• TSR-Name
• Service-Description: Identifies a specific UE traffic. (ex: 5 tuples, application id)
• Traffic-Steering-Policy-Identifier: reference to a pre-configured set of service functions.
• Precedence: Priority order of the traffic steering policy.
• Interfaces used to provide TSR
• Sd/Gx Interface (PCRF <> PCEF/TDF)
• St Interface (PCRF <> SCTCF)
Service Chaining ~ Overview as of 2015/10/05 13
Refer to tables below for details of information included in each components of TSR
* Sd/Gx : Table 6.2.1.1.2-1: Mapping of components of TSP to information over Sd/Gx interface
* St : Table 6.2.1.3.1.1-1: The TS Rule Information

14. Where discussions are happening? 3GPP | IETF | ONF
• Describing Service Chaining
• [TR.22.808] Study on Flexible Mobile Service Steering (FMSS)
• [TR.23.718] Architecture Enhancement for Flexible Mobile Service Steering
• Not directly but closely related.
• [TS.23.203] Policy and charging control architecture
• [TS.29.212] Policy and Charging Control (PCC); Reference points
• Good to read to understand 3GPP terms and technology.
• [TR 21.905] Vocabulary for 3GPP Specifications
• [TS.23.003] Numbering, addressing and identification
• [TS.23.401] General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network
(E-UTRAN) access
• [TS.29.061] Interworking between the Public Land Mobile Network (PLMN) supporting packet based services and
Packet Data Networks (PDN)
• About SGi-interface
• [TS.29.274] 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for
Control plane (GTPv2-C); Stage 3
• [TS.29.281] General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U)
Service Chaining ~ Overview as of 2015/10/05 14
Other 3GPP documents related to Service Chaining
TR: Technical Report
TS: Technical Specification

15. Where discussions are happening? 3GPP | IETF | ONF
IETF : Service Function Chaining WG
http://datatracker.ietf.org/wg/sfc/
• Defines a new encapsulation format (NSH) which includes:
• Service Path ID which specifies the Service Function Path.
• Service Index which is a sequence number of service functions.
• Context Header and Metadata to pass context information between nodes.
• Also discussing / defining below in Internet-Drafts and RFCs.
• Problem Statement and Use Cases.
• Architectural building blocks and their relationships.
• Control Plane Mechanisms and Manageability.
(*) NSH … Network Service Header
Service Chaining ~ Overview as of 2015/10/05 15

16. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 16
https://datatracker.ietf.org/wg/sfc/documents/
Internet-Draft / RFC under SFC-WG
1. Read this first to get overview
3. Use Cases
2. Encap Format (NSH)

17. Where discussions are happening? 3GPP | IETF | ONF
Service Chaining ~ Overview as of 2015/10/05 17
Roles defined in IETF SFC
Classifier Forwarder
Proxy
SFSF
SFSF
NSH Label aware SFs.
NSH Label un-aware SFs.
Labeled
Not Labeled
Could be on same physical box or on different boxes / VMs.
Packet NSH
Packet

18. Use Case Models
Service Chaining
Service Chaining ~ Overview as of 2015/10/05 19

19. Use Case Models
• Document below describes use case model in Mobile environment.
• “Service Function Chaining Use Cases in Mobile Networks”
• draft-ietf-sfc-use-case-mobility-04
• Possible Service Functions discussed in the document.
• Performance Enhancement Proxies (PEPs)
• Deep Packet Inspection (DPI)
• Web and Video optimizations
• Subscriber and service policy controlled dynamic network adaption
• Analytics and management support
• TCP optimization
• HTTP header enrichment
Service Chaining ~ Overview as of 2015/10/05 20
Use case model in Mobile environment

20. Use Case Models
• Classification Scheme
• Classification at P-GW based on APN.
• Classification at PCEF and TDF.
• Typical metadata and their sources:
• UE: terminal type (e.g., vendor), IMSI (country, carrier, user)
• GTP tunnel endpoint: eNB-Identifier, time, and many more
• PCRF: subscriber info, APN (service name), QoS, policy rules
Service Chaining ~ Overview as of 2015/10/05 21
Use case model in Mobile environment
PCEF : Policy and Charging Enforcement Function
TDF : Traffic Detection Function
PCRF : Policy and Charging Rules Function
https://datatracker.ietf.org/doc/draft-ietf-sfc-use-case-mobility/

21. Use Case Models
• Document below describes use case model in Mobile environment.
• “Service Function Chaining Use Cases In Data Centers”
• draft-ietf-sfc-dc-use-cases-03
• Possible Service Functions discussed in the document.
• Firewalls (Edge, Segment and Application)
• WAN and application acceleration
• Deep Packet Inspection (DPI)
• Intrusion Detection and/or Prevention System (IDS/IPS)
• Server Load Balancers, Application Delivery Controller (ADC)
• NAT44 [RFC3022], NAT64 [RFC6146]
• HOST_ID injection
• HTTP Header Enrichment functions
• TCP optimizer
• Monitoring
Service Chaining ~ Overview as of 2015/10/05 22
Use case model in Data Center environment

22. Use Case Models
• Traffic and associated SFCs in Data Center are classified into two types.
1. North-South Traffic / SFC.
• Originates from outside the data center.
• Typically associated with users at onsite, remote and VPN
• Traverse among Service Functions below.
2. West-East Traffic / SFC.
• Traffic steered among servers inside Data Center to instantiate services.
Service Chaining ~ Overview as of 2015/10/05 23
Use case model in Data Center environment

23. Implementation
Service Chaining
Service Chaining ~ Overview as of 2015/10/05 24

24. Service Chaining Implementation
1. Classify and forward based on existing protocol headers.
• Fastest way to start Service Chaining deployment.
• Pros: Could use existing OpenFlow switches.
• Cons: Requires many rules. (hardware switches might not be capable)
2. Introduce new header, NSH.
• Discussed as “Service Function Chaining (SFC)” in IETF SFC WG.
• Pros: Requires less rules.
• Cons: No production level implementation exists.
• Cons: Service Function need to support it. (or use proxy)
• Mix of the above two could be used during transition phase.
Service Chaining ~ Overview as of 2015/10/05 25
Two ways to implement Service Chaining

25. Service Chaining Implementations
• Hardware based Forwarder / Proxy / Classifier.
• Switches supporting OpenFlow are available from multiple vendors.
• However, most OpenFlow SWs lack flexibility of pipeline and scalability of flow rules.
• No switch available supporting the new header discussed at IETF, NSH.
• Some vendors has POC implementation using NPU, but not shown public yet.
• Software based Forwarder / Proxy / Classifier.
• VXLAN+NSH patch for OVS by Pritesh Kothari at Cisco.
• https://github.com/pritesh/ovs/tree/nsh-v8
• https://www.ietf.org/proceedings/92/slides/slides-92-sfc-8.pdf
• Controller / Orchestrator
• OpenDaylight
• https://wiki.opendaylight.org/view/Service_Function_Chaining:Main
• Discussion to extending OpenFlow protocol to support NSH is ongoing.
• Service Function
• None, as far as I’m aware of.
Service Chaining ~ Overview as of 2015/10/05 26
Available implementations as of 2015 Oct.

26. What do we need to move forward?
Service Chaining
Service Chaining ~ Overview as of 2015/10/05 27

27. What do we need to move forward?
• Network ASIC needs to support flexible rules and more flow rules.
• Increase of TCAM size & programmable pipeline support is required.
• Programmable pipeline is ready by Cavium XPliant.
• http://www.cavium.com/XPliant-Ethernet-Switch-Product-Family.html
• Maybe on Broadcom Tomahawk as well, but details not disclosed to public.
• No ASIC with large TCAM yet
• 40+Mbit TCAM to support 100K+ rules with IPv6 + 5 tuple
• Many core servers with DPDK could improve performance significantly.
• Open Data Plane (ODP) + ARM many core actively working.
• http://www.opendataplane.org/
Service Chaining ~ Overview as of 2015/10/05 28
Classifier + Forwarder (without NSH)

28. What do we need to move forward?
• High performance Hardware Switch supporting NSH as Forwarder.
• Support of NSH is the only missing piece.
• Should be possible by next year using new ASICs already announced today.
• Classifier scale out
• Software Scale out?
• Many classifier entities on VMs or Many Core Server.
• Good especially when parsing metadata in NSH is required.
• How to distribute among classifier entities need consideration to avoid re-
ordering of packets in same flow.
• ECMP hash based on source IP address, 5 tuple or both?
Service Chaining ~ Overview as of 2015/10/05 29
Classifier + Forwarder (with NSH)

29. What do we need to move forward?
• Proxy to Pop/Push NSH based on pre-defined rule
• Hardware Switch with NSH support should have best cost/performance.
• Co-existing with Classifier / Forwarder might be possible and feasible.
• More feature rich Proxy
• Using metadata info in NSH will require to keep state on Proxy.
• Software Scale Out design might be suited.
• Could be a place to inject new features still not thought of.
Service Chaining ~ Overview as of 2015/10/05 30
SFC (NSH) Proxy

30. What do we need to move forward?
Contact ebiken.g@gmail.com or Twitter: @ebiken
• More study required on ideal architecture and transition plan.
• Phased approach would be required especially for enterprise
datacenter use case.
• Cannot replace all switches to support NSH at once.
• Need more POC and production implementation.
• Switch using new Network ASIC or FPGA/NPU.
• Enhancements to Linux Kernel, Software Switch (OVS, Lagopus etc.)
• Many core SoC is also an option.
Service Chaining ~ Overview as of 2015/10/05 31
Interested for more discussions or hacking together?