1. Network Service Header (NSH) draft-quinn-sfc-nsh IETF 90
P. Quinn, et. al
Cisco Systems
P. Agarwal
R. Manur
Broadcom
Pankaj Garg
Microsoft
A. Chauhan
Citrix
U. Elzur
Intel
B. McConnell
Rackspace
C. Wright
Red Hat Inc.

2. NSH Overview
Describes a dataplane header used to carry information along a service path.
Identifier for service path selection
Opaque mandatory metadata fields
Optional TLVs
Creates “service plane”
Transport independent (NSH in VXLAN, NSH in MPLS, NSH in UDP, etc.)
Service layer OAM

3. Changes from -02 New co-author
Base header is first 4 bytes, includes type field
Encapsulated protocol type  8 bit value
Explicit dataplane versioning
Critical TLV indicator
4 byte service path header
Added optional metadata TLV (in addition to mandatory fixed context header)
TLV Class

4. Implementation Update
Opensource implementations
OVS dataplane (with VXLAN)
OpenDaylight control plane (+ LISP)
Several vendor specific implementations
Early deployments underway

5. Base Header
|Ver|O|C|R|R|R|R|R|R| Length | MD Type | Next Protocol |
8 bit Next Protocol: support non-ET protocols + reclaim space
MD type indicates format of header. NSH type = 0x1
Critical TLV present

6. Service Path Header Represents the rendering of the chain policy
| Service Path ID | Service Index |
Represents the rendering of the chain policy
Simple identifier: does not imply a static, explicit path
Resolved locally
Can be changed: branching within a service graph
Re-classification (and therefore policy) decision
Index conveys node within the graph

7. Chain and Paths (no load distribution)
Chain1: Firewall  DPI  IPS
Chain1 is rendered as SFPID = 10 FW
FW’
IPS
IPS’
DPI’
FW’’’’
DPI
IPS’’
DPI’
Classifier
SFF1
SFF2
SFF3
SFPID: 10  SF1: FW
SFPID: 10  SF2: DPI
SFPID: 10  SF2: DPI
Loc(SFF1, FW, FW’)
Loc(SFF2, FW’’)
Loc(SFF3, FW’’’’)
Loc(SFF3,DPI)
Loc(SFF2,DPI’)
Loc(SFF2, IPS’)
Loc(SFF1, IPS)
Loc(SFF3, IPS’’)
Local forwarding policy
Local forwarding policy
Local forwarding policy
Transport
Transport
Transport

8. Mandatory Context Headers
| Network Platform Context | | Network Shared Context | | Service Platform Context | | Service Shared Context |
Based on initial deployments: many use cases satisfied
with fixed size context headers
Hardware friendly: easy to parse and skip at high speed
Opaque, significance allocated via control plane

9. Optional TLV TLV Class: describes the scope of the type field
| TLV Class | Type |R|R|R| Len |
| Variable Metadata |
TLV Class: describes the scope of the type field
Type: type of metadata carried, includes critical indication

10. Next Steps Continue development Continued deployments
Opensource and vendors
Continued deployments
Ask for adoption as a working group document: SFC encapsulation
“Generic SFC Encapsulation: This document will describe a single service-level data plane encapsulation format that:
- indicates the sequence of service functions that make up the Service Function Chain
- specifies the Service Function Path,
- communicates context information between nodes that implement 
service functions and Service Function Chains…”