cdn and isp operation

S O L U T I O N S

c o mm V e r eG • Hong Kong

• Bangkok

• Beijing

• Brunei

• Kuala Lumpur

• Manila

• San Jose

• Seoul

• Shanghai

• Singapore

• Taipei

Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM

2010/12/2, Taipei

智匯亞洲有限公司許至凱 CCIE/JNCIE

kaeatforum [at] gmail.com

CDN (Content Delivery Network) and ISP Operation

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Global IPv6 Summit in Taiwan & 15th TWNIC IP OPM; 2010/12/2 Taipei

Agenda

CDN Introduction– “Pro” CDN period– Global Server Load Balancing– CDN mechanism

ISP Operation Issues– CDN issues in regular operation– Any aggressive strategy for CDN?

Q & A

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CDN evolution

Pro-CDN period– Before Y2000

• Server farm

• 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

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Pro-CDN period

WWW access concept:

– 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

Internet

Internet

HTTP

HTML

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Ultimate version

– Meet huge subscribers• Lots servers

• Load balance mechanism

• Reverse cache

Internet

HTTP/HTTPS

Reverse Proxy

Content Switch

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“SIZE” is really a issue!

Think about:– Million even billion subscribers!

• Huge web servers

• 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

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GSLB example

Internet

DNS Server

Client request

GSLB cooperation

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GSLB factors

Mechanisms for “balancing”– Passive Techniques

• DNS Round-Robin

• 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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Content Delivery Networks

Extend GSLB concept to achieve:– Scalability– Security– 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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Common CDN mechanism concept

HTTP

HTML

CDN

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DNS query mechanism recap

Iteration resolution

1. www.abc.com=?

“.“ NS

“.com“ NS

“abc.com“ NS

2. www.abc.com=?

3. ask “com” NS

4. www.abc.com=?

6. www.abc.com=?

7. www.abc.com=IP

5. ask “abc.com” NS

8. www.abc.com=IP

Client ISP DNS Server

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DNS “view”

BIND could response different queried IP information based on client IP address– Useful for separating “internal” and “external”

www.abc.com=?

ISP A DNS Server

ISP B DNS Server

ISP A Client

ISP B Client

www.abc.com=IP A

www.abc.com=?

www.abc.com=IP B

www.abc.com=?www.abc.com=IP A

www.abc.com=?

www.abc.com=IP B

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How CDN “cache” content?

Un-cooperative pull-based CDN architecture

1. DNS query

2. DNS query 3. DNS response

4. DNS response

CDN DNS server

ISP DNS server

CDN server Real content

5. HTTP Get6.5 HTTP Get if

cache miss

7. Response6/8. Response

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CDN issues in ISP operation

Monitoring & troubleshooting difficulty– Regular tools based on L3/L4 are not enough

• Ping/Traceroute etc.

– Comprehensive L7 monitoring tools is necessary• Webperf

DNS– Geographic DNS response will be impacted by open DNS

service• ex. Google DNS

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DNS issues in CDN

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Surrogate server location issue

Surrogate server installed in ISP network– There is a potential side effect if ISP cooperate with CDN

provider• Peering/transit bandwidth cost

ISP A

Customer

ISP B

Peering Cost?

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Aggressive strategy face to CDN

Forward Proxy– Before CDN, ISP apply some mechanism to enhance using

experience

– Proxy did not work when• Lots of objects is non-cacheable

• HTTP % in whole traffic pattern decrease

Transparent proxy

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Aggressive strategy face to CDN

“Cache” content– “Replicate” by ISP-self

• Original traffic pattern

• Centralize traffic comes from/to CDN servers

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Future discussion

ISP self-owned CDN?– Content source?– Network scalability in Taiwan?

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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 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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Q & A

cdn and isp operation

Technology