Providing End-to-End Network
QoS via Overlay Networks and
Bandwidth On-demand
Mauricio Arango
Sun Microsystems
October 2007
Mauricio.Arango@sun.com 1

Internet’s QoS Problem – A result of
the Dumb Network Approach
• Based on End-to-end principle:
> Advocates minimal core network functions with emphasis
on functions at the periphery
> Routing is part of core functions – tightly coupled with
packet switching fabric, highly distributed
• Problem - Emphasis on minimal core functions left
out key basic features:
> Quality of Service (QoS)
> Performance Monitoring
> Accounting
• A solution - Add needed core functions,
“Intelligence”, via Overlay Networks on top of
current dumb core 2

Internet’s QoS Problem – A
business opportunity
• Lack of assured QoS is a business problem
> “Throwing more bandwidth” solution approach isn’t cost-
effective
• Rapid traffic growth, specially video, exacerbating
problem
• Growing business sectors exploiting opportunity
through overlay network approaches
> Content Delivery Networks (CDN) - Managed QoS
services
> Application Delivery and Wide-area Optimization
Controllers
3

The QoS problem is a routing
problem
• Internet’s routing
> Doesn’t take into account network performance
conditions
> Doesn’t take into account endpoint performance
conditions, such as data center problems
• Overlay solution approach
> Why - Changing existing infrastructure is too complex
and expensive
> How – hierarchical routing – adding higher-level routing
layer that bases decisions on performance data
4

Overlay Networks
• Compensate network weaknesses with computing
power: e.g. caching, application-based routing
> An application of Butler Lampson’s principle: "All problems in
computer science can be solved by another level of indirection"
5

Overlay Architecture Patterns Remote Decision Point
Control & Management Overlay
Remote Remote
Decision point Decision point
Interception points Interception & local decision points
Backbone
DNS
ISP
Server
Backbone
Backbone ISP Customer
Access ISP Network
ISP Backbone
Backbone ISP
ISP
Internet Backbone
• Interception Point – Network element on path of traffic
flow, performs packet inspection. Minimally invasive:
> Open control points – eg. DNS
> Interconnection points – eg. peering points
• Decision Point – Applies rules and executes triggered
actions – local or remote 6

Telco Overlay – PSTN Intelligent
Network
• Most widely adopted PSTN overlay architecture
> Goal was to add new telephony services faster and at
lower cost
> Making changes in central office and switches was too
complex and expensive
• Architecture
> Trigger Points – Interception & local decision points
> Service Control Point (SCP) – Remote decision point
7

Session Control Overlay - SIP
Remote Decision Point
Application SIP
Overlay App Server
Interception & local
decision point
SIP routing SIP SIP SIP
overlay Proxy Proxy Proxy
DNS Internet
Backbone
In-network Interception &
local decision point 8

QoS Overlay – Caching System
Remote decision point –
Application-level routing
Caching Control
Overlay
4
DNS Caching QoS
Proxy 5 Manager Monitoring
Interception point
6
3
Caching Origin
Server Server
2 7
1 DNS
Internet
9

Load-balancing Overlay – wide-area
& local Remote decision point –
Application-level routing
Load-balancing Overlay
Wide & local QoS
DNS area load-
Proxy Monitoring
balancer
Interception &
Decision point
Interception Data
point Center B
Data
Load Center
Balancer Network
DNS
Data Center A
Internet
10

QoS Routing Overlay – Best wide-
area path selection
QoS Routing Overlay Remote decision point –
Application-level routing
DNS QoS QoS
Proxy Routing Monitoring
Path Data
Interception & Traffic Center
entry point Decision points Manager Network
switch
Data Center
DNS Backbone ISP 1
Access
ISP Backbone ISP 2
On-demand
connection
11

Systems requirements for Overlay
network patterns
• Interception and local decision points
> Based on commercial off-the shelf COTS systems with
multi-threaded architecture – exploiting parallelism in
packet processing
> Packet classification (deep packet inspection) –
sophisticated rule-based system – beyond header fields,
capable of handling application-level strings
> Via packet processing engines – e.g. on top of bare HW (Netra
Data Plane Suite) or new OS functions (Solaris Crossbow)
> New APIs manage packet classification rules
• Remote decision points – COTS-based
> APIs with interception and local decision points
12

Conclusions & Outlook
• Wide range of overlay architectures can be designed with
basic patterns – Simplified approach for design of QoS
overlays
• Market for QoS solutions influencing networking trends
> Increased use of application-driven routing - Separation from
switching fabric
> Increased centralization of routing and other transport control
functions
> Increased centralization of performance management and
accounting
> Increased use of on-demand bandwidth via connection-oriented
services
13