The material I presented in 2010 Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM (Dec. 2nd, 2010)

1. c o m m Ve r Ge • Hong Kong
S O L U T I O N S
• Bangkok
Global IPv6 Summit in Taiwan • Beijing
& 15th TWNIC IP OPM • Brunei
2010/12/2, Taipei • Kuala Lumpur
• Manila
• San Jose
CDN (Content Delivery Network) • Seoul
• Shanghai
and ISP Operation
• Singapore
• Taipei
智匯亞洲有限公司
許至凱 CCIE/JNCIE
kaeatforum [at] gmail.com

2. Agenda
 CDN Introduction
– “Pro” CDN period
– Global Server Load Balancing
WWW.COMMVERGE.COM
– CDN mechanism
 ISP Operation Issues
– CDN issues in regular operation
– Any aggressive strategy for CDN?
Q&A
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 2
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3. CDN evolution
 Pro-CDN period
– Before Y2000
• Server farm
WWW.COMMVERGE.COM
• Caching
 First generation CDN
– 2000 ~ 2005
• Static or dynamic HTML content
 Second generation CDN
– 2005 ~ 2010
• Video、Streaming
 Third generation CDN
– 2010 ~
• Community based service
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 3
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4. Pro-CDN period
 WWW access concept:
WWW.COMMVERGE.COM
HTTP
Internet HTML
Internet
– More challenges when:
• Subscriber volume is increasing quickly
• High available, none-stop service request
– Annual 5.256 minutes down-time only for 99.999% SLA
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5. Ultimate version
– Meet huge subscribers
• Lots servers
• Load balance mechanism
WWW.COMMVERGE.COM
• Reverse cache
Reverse Proxy
HTTP/HTTPS
Internet
Content Switch
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6. “SIZE” is really a issue!
 Think about:
– Million even billion subscribers!
• Huge web servers
WWW.COMMVERGE.COM
• Complex content switch architecture
• Ultra-large Internet bandwidth request
 Following issues still do not be solved:
– Single point-of-failure
– Slow response when server is far away from subscriber
 Solution: deploy web server around the world
– Keep good performance
– Provide “real” high availability
• “Disaster recovery” is included here
 Global Server Load Balancing
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 6
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7. GSLB example
WWW.COMMVERGE.COM
GSLB
cooperation
Client
request
Internet
DNS Server
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 7
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8. GSLB factors
 Mechanisms for “balancing”
– Passive Techniques
• DNS Round-Robin
WWW.COMMVERGE.COM
• DNS RTT
• BGP Anycast
• DNS/Routing Hybrid
– Footrace Techniques
• DNS footraces
• HTTP-redirect footraces
• TCP handshake footraces
– Active Techniques
• DNS probes Measurement
• HTTP probes
• HTTP redirection
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9. Content Delivery Networks
 Extend GSLB concept to achieve:
– Scalability
– Security
WWW.COMMVERGE.COM
– Reliability
– Responsiveness
– Performance
 Two major CDN operators:
– Commercial CDNs
• Market leader: Akamai technologies
– Install 73000 servers in 70 countries
– Handle 15% ~ 20% Internet traffic
• Others: EdgeStream, Limelight Networks, Mirror Image
– Academic CDNs
• CoDeeN, Coral, Globule
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10. Common CDN mechanism concept
WWW.COMMVERGE.COM
HTTP
HTML
CDN
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11. DNS query mechanism recap
 Iteration resolution
WWW.COMMVERGE.COM
1. www.abc.com=? 2. www.abc.com=?
8. www.abc.com=IP 3. ask “com” NS
Client ISP DNS Server “.“ NS
4. www.abc.com=?
5. ask “abc.com” NS
“.com“ NS
6. www.abc.com=?
7. www.abc.com=IP
“abc.com“ NS
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12. DNS “view”
 BIND could response different queried IP information
based on client IP address
– Useful for separating “internal” and “external”
WWW.COMMVERGE.COM
www.abc.com=?
www.abc.com=IP A
ISP A Client ISP A DNS Server
www.abc.com=?
www.abc.com=IP B
ISP B Client ISP B DNS Server
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13. How CDN “cache” content?
 Un-cooperative pull-based CDN architecture
WWW.COMMVERGE.COM
6.5 HTTP Get if
5. HTTP Get cache miss
6/8. Response 7. Response
CDN server Real content
1. DNS query 4. DNS response
ISP DNS server
2. DNS query 3. DNS response
CDN DNS server
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 13
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14. CDN issues in ISP operation
 Monitoring & troubleshooting difficulty
– Regular tools based on L3/L4 are not enough
• Ping/Traceroute etc.
WWW.COMMVERGE.COM
– Comprehensive L7 monitoring tools is necessary
• Webperf
 DNS
– Geographic DNS response will be impacted by open DNS
service
• ex. Google DNS
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 14
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15. DNS issues in CDN
WWW.COMMVERGE.COM
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 15
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16. Surrogate server location issue
 Surrogate server installed in ISP network
– There is a potential side effect if ISP cooperate with CDN
provider
WWW.COMMVERGE.COM
• Peering/transit bandwidth cost
ISP A
Peering
Cost?
ISP B
Customer
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 16
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17. Aggressive strategy face to CDN
 Forward Proxy
– Before CDN, ISP apply some mechanism to enhance using
experience
WWW.COMMVERGE.COM
Transparent
proxy
– Proxy did not work when
• Lots of objects is non-cacheable
• HTTP % in whole traffic pattern decrease
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 17
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18. Aggressive strategy face to CDN
 “Cache” content
– “Replicate” by ISP-self
• Original traffic pattern
WWW.COMMVERGE.COM
• Centralize traffic comes from/to CDN servers
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 18
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19. Future discussion
 ISP self-owned CDN?
– Content source?
– Network scalability in Taiwan?
WWW.COMMVERGE.COM
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20. Reference
– Content Networking: Architecture, Protocols, and Practice (The
Morgan Kaufmann Series in Networking)
» Markus Hofmann, Leland R. Beaumont
– Content Delivery Networks (Lecture Notes in Electrical
WWW.COMMVERGE.COM
Engineering) Content Delivery Networks (Lecture Notes in
Electrical Engineering)
» Rajkumar Buyya, et al
– Optimizing Network Performance with Content Switching: Server,
Firewall and Cache Load Balancing
» Matthew Syme, Philip Goldie
– Content Delivery Networks: Web Switching for Security,
Availability, and Speed
» Scot Hull
– A Practical Guide to Content Delivery Networks, Second Edition
» Gilbert Held
– DNS and BIND (5th Edition)
» Cricket Liu, Paul Albitz
– Content Networking Fundamentals
» Silvano Da Ros.
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21. Q&A
WWW.COMMVERGE.COM
Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 21
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