Multimedia networks, Study notes of Telecommunication electronics

Download Multimedia networks and more Study notes Telecommunication electronics in PDF only on Docsity!

Multimedia

Lecture # 14

Muhammad Ali Faisal

Chapter 7 outline

 (^) 7.1 Multimedia Networking Applications  (^) 7.2 Streaming stored audio and video  (^) 7.3 Real-time Multimedia: Internet Phone study  (^) 7.4 Protocols for Real-Time Interactive Applications  (^) RTP,RTCP,SIP  (^) 7.5 Distributing Multimedia: content distribution networks

 (^) 7.6 Beyond Best Effort  (^) 7.7 Scheduling and Policing Mechanisms  (^) 7.8 Integrated Services and Differentiated Services  (^) 7.9 RSVP

Content distribution networks (CDNs)

Content replication

 CDN (e.g., Akamai)

customer is the content

provider (e.g., CNN)

 CDN replicates

customers’ content in

CDN servers. When

provider updates content,

CDN updates servers

origin server in North America

CDN distribution node

CDN server in S. America (^) CDN server in Europe

CDN server in Asia

CDN example

origin server (www.foo.com)

 distributes HTML

 replaces:

http://www.foo.com/sports.ruth.gif with http://www.cdn.com/www.foo.com/sports/ruth.gif

HTTP request for www.foo.com/sports/sports.html

DNS query for www.cdn.com

HTTP request for www.cdn.com/www.foo.com/sports/ruth.gif

1 2

3

Origin server

CDNs authoritative DNS server

Nearby CDN server CDN company (cdn.com)  (^) distributes gif files  (^) uses its authoritative DNS server to route redirect requests

Improving QOS in IP Networks

Thus far: “making the best of best effort” Future: next generation Internet with QoS guarantees  (^) RSVP: signaling for resource reservations  (^) Differentiated Services: differential guarantees  (^) Integrated Services: firm guarantees  (^) simple model for sharing and congestion studies:

Principles for QOS Guarantees

 (^) Example: 1Mbps IP phone, FTP share 1.5 Mbps link.  (^) bursts of FTP can congest router, cause audio loss  (^) want to give priority to audio over FTP

packet marking needed for router to distinguish between different classes; and new router policy to treat packets accordingly

Principle 1

Principles for QOS Guarantees (more)

 (^) Allocating fixed (non-sharable) bandwidth to flow: inefficient

use of bandwidth if flows doesn’t use its allocation

While providing isolation, it is desirable to use resources as efficiently as possible

Principle 3

Principles for QOS Guarantees (more)

 (^) Basic fact of life: can not support traffic demands beyond link capacity

Call Admission: flow declares its needs, network may block call (e.g., busy signal) if it cannot meet needs

Principle 4