Transcript Document

Infrastructure for Better Quality
Internet Access & Web Publishing
without Increasing Bandwidth
Prof. Chi Chi Hung
School of Computing, National University of Singapore
Lower Kent Ridge Road, Singapore 119260
Email: [email protected]
David Goss
Microbits
Email: [email protected]
QoS Content Delivery Services
& its Challenges
Internet Content Delivery Today
Internet
hi
hola
Client: Last Mile
Access
1-to-Many
(Dynamic)
Centralized
Content Servers
Content
Basic Content Delivery Problems
THREE BIG PROBLEMS:
• Long latency for the ever increasing bandwidth.
• Increasing bandwidth cannot catch up with increasing network
demand.
• High client expectation with commercial and real-life applications.
• Fast network is never fast enough with ever increasing user’s realtime expectation.
• Content creation and delivery heading in opposite directions.
• Easy handling of sophisticated multimedia data usually means
longer delay time for web surfing.
Content Delivery Challenges
THREE GOALS:
• Fast Content Delivery for the given bandwidth.
• Quality Content Presentation under wide variations of
clients/devices/networks.
• Efficient Content Management & Monitoring for one
single source of content and network resource.
Content Delivery Approaches…
Four APPROACHES:
• Client Plug-ins: “Fat clients doing work in the last stage of
delivery?”
• Server: “Network is computing, is computing outside network?”
• Proxy Gateway: “Network is computing, is selective computing
inside the network?”
• Data Replication “Web data is replicated in servers at the client
edge of Internet, how big is the client population for cost effective
solution?”
Considerations:
• Cost Effectiveness
• Server Collaboration
• Client Constraints
• Action Point of Tasks
Recommended Direction
“Network is computing and business;
selected computing, services and policy
management is in the network.”
“1-to-many ACTIVE PROXY CACHE
solution as compared to individual
server or client approach.”
Fast Content Delivery
Content Delivery Mechanism
ISP
Internet
(Large Backbone ISP)
Content
Web Page Retrieval (against time):
Basic Frame Object
Embedded Obj. Embedded Obj.
Embedded Obj.
Embedded Obj. Embedded Obj.
Embedded Obj. Embedded Obj.
Embedded Obj. Embedded Obj.
Four Delivery Techniques
INCREASING DELIVERY SPEED FOR A GIVEN
BANDWIDTH:
• Caching for data reuse
• Compression for reducing bandwidth consumption for a given
amount of information.
• Acceleration for improving latency time of 1st time access.
• Priority for important web access.
Fast Delivery Techniques (I): Caching
How Cache Works?
GET full-URL HTTP/1.1 www_proxy.my.domain
Client
Web
Cache
Request
Any supported
protocol
Response
HTTP/1.1 200 document
follows
Disk
some host
Remote
Server
Fast Delivery Techniques (I): Caching
How Cache Works?
GET full-URL HTTP/1.1 www_proxy.my.domain
Client
Web
Cache
HTTP
HTTP/1.1 200 document
follows
Disk
some host
Remote
Server
Fast Delivery Techniques (I): Caching
ISP
Content
Proxy Cache
Content
Internet
(Large Backbone ISP)
Reverse Proxy
Cache
Content
Content
Forward Proxy for Clients:
Reverse Proxy for Servers:
• Save international bandwidth
• Reduce server workload
• Reduce access latency through
local access
• Cost-effective sol’n than server
through specialized hardware
• Reduce server workload
• Memory access instead of disk
operation
Fast Delivery Techniques (I): Caching
Necessary but Not Sufficient …
• 1st Web Object Retrieval over 70% web objects without reuse
• SMEs low volume network traffic implies less caching effect;
slower links also shift bottleneck from startup time to network delay.
• Non-Cachable Decision for dynamic data content.
• Over-Demand for Network Bandwidth for a fixed amount
of data information.
Fast Delivery Techniques (II): Compression
ISP
Internet
(Large Backbone ISP)
Content
Content
Compression
Proxy Cache
Compression
Reverse Proxy
Content
Content
Content
Web Page Retrieval:
Compression Proxy:
• Reducing BW consumption through
lossless & lossy compression
• Improve response time of surfing (in
particular, modem & reverse proxy)
• Browser support through HTTP
Basic Frame Object
Embedded Obj. Embedded Obj.
Embedded Obj.
Embedded Obj. Embedded Obj.
Embedded Obj. Embedded Obj.
Embedded Obj. Embedded Obj.
Fast Delivery Techniques (II): Compression
Original File
File Size: 176,726 bytes
File Size: 29,467 bytes
Savings: 83.3 %
Fast Delivery Techniques (III): Acceleration
ISP
Internet
(Large Backbone ISP)
Content
Content
Active Proxy
Cache
Active Reverse
Proxy Cache
Content
Content
Content
Web Page Retrieval:
Acceleration Proxy:
• Acceleration through parallel fetch of
objects in proxy
• Re-scheduling for early object fetching
• No increase in bandwidth demand.
Basic Frame Object
Embedded Obj.
Embedded Obj.
Embedded Obj.
Embedded Obj.
Embedded Obj.
Embedded Obj.
Embedded Obj.
Embedded Obj.
Embedded Obj.
Fast Delivery Techniques (IV): Priority
ISP
Internet
(Large Backbone ISP)
Active Proxy
Cache
Active Reverse
Proxy Cache
Priority Proxy:
Priority Based on:
• Different user groups assigned with
different priority level to use network.
• Better load balancing network usage.
• Important to situations with VIP or
super users.
• User ID and IP addresses.
• Object sizes and types.
• Time of access.
• Destination.
Fast Delivery Solutions (I)
Opportunity 1: Active Proxy Cache
• Caching to shortcut data retrieval path to local machine and to
reduce international bandwidth consumption.
• Acceleration to speedup necessary accesses of web data
retrievals through parallelism and re-scheduling of object retrieval.
• Compression and Transcoding to reduce bandwidth
consumption for the same amount of content (important for wireless
and low-speed modem accesses).
• Priority Access to allocate more bandwidth to more
urgent/important requests.
Fast Delivery Solutions (II)
Opportunity 2: Active Reverse Proxy Cache
• Caching to reduce delay due to server I/O and disk operations.
• Compression and Transcoding to reduce bandwidth
consumption for the same amount of content.
Infrastructure for Better Web
Content Delivery
Active CDN Framework (I)
SW Application “Chips”
Security
Anti-Virus
Wireless
Filtering
Priority Access
Ad-Insert
Acceleration
Compression
API Interface To
Applications
Efficient Active Proxy Framework
Active CDN Framework (II)
ISP
Active Proxy
Cache
Proxy Cache
Transformer
Internet
(Large Backbone ISP)
Active Reverse
Proxy Cache
Sample Case Study
Typical Education Environment & Needs
• Limited Number of Students
• Caching is important, but its effect is limited (e.g. hit ratio less than
30%).
• Accelerating 1st time access is very important.
• Typical acceleration gain is about 20% to 40%.
• Teaching Staff and Students
• Larger number of students over staff implies the importance of
higher priorities for web requests related to teaching and staff
administration.
• Content Management
• Centralized content management in the institution gateway is
critical.
Q&A