[Cisco, Brocade]: Overview of Service Functions Deployment Issues

An IETF document by Paul Quinn, Cisco Systems and Thomas Nadeau [pictured], Brocade "provides an overview of the issues associated with the deployment of service functions (such as firewalls, load balancers, etc.) in large-scale environments"

Introduction 

The delivery of end-to-end services often require various service functions including traditional network service functions (for example firewalls and server load balancers), as well as application- specific features such as http header manipulation. Service functions may be delivered within the context of an isolated user (e.g. a tenant), or shared amongst many users/user groups. 

Current service function deployment models are often tightly coupled to network topology and physical resources resulting in relatively rigid and static deployments. The static nature of such deployments greatly reduces, and in many cases, limits the ability of an operator to introduce new or modify existing services and/or service functions. Furthermore there is a cascading effect: changing one (or more) elements of a service function chain often effects other elements in the chain and/or the network elements used to construct the chain. 

This issue is particular acute in elastic service environments that require relatively rapid creation, destruction or movement of physical or virtual service functions or network elements. Additionally, the transition to virtual platforms requires an agile service insertion model that supports elastic and very granular service delivery, and post-facto modification; supports the movement of service functions and application workloads in the existing network, all the while retaining the network and service policies and the ability to easily bind service policy to granular information such as per-subscriber state. 

This document outlines the problems encountered with existing service deployment models for Service Function Chaining (SFC) (often referred to simply as service chaining; in this document the terms will be used interchangeably), as well as the problems of service chain creation, deletion, modification/update, policy integration with service chains, and policy enforcement within the network infrastructure. The document highlights three key areas of WG focus for addressing the issues highlighted in this draft that will form the basis the possible WG solutions that address the current problems.

See "Service Function Chaining Problem Statement draft-ietf-sfc-problem-statement-11.txt" - here.