11-12 February 2006, T.I.F.R., Mumbai, India


chep06 pre-conference School organized in collaboration with

Fundamentals Series

1 Fundamentals of Grid Technologies

2 Computer Security 1:
Cryptography and
Security Protocol

3 Fundamentals of
Networking QoS

In-depth Series

4 Computer Security 2:
From Theory to Implementation

5 Pragmatic Software Engineering

6 Working with databases and database-centric interfaces

All lecture series
Practical Information
Chep06 conference

Printable Version


Lecture Series 3

Fundamentals of Networking QoS


A few questions

  • Have you ever heard of Difserv or NIS?

  • Do you know what MPLS is and how it can help guaranteeing service quality?

  • Do you know how network congestion can be avoided in the Internet?

  • Do you know how TCP is designed to limit congestions and how it should be tuned for better performance?

  • Do you know what Random Early Detection or Explicit Congestion Notification means?

  • Do you know which specific protocols are required to support Audio and Video over the Internet, and why?

All the answers at School@chep06

Sunday 12 February 2005

09:00 12:25

François Flückiger


Fundamentals of Networking QoS


Improving Quality of Service guarantees and performances in data network is a key requirement of Grid computing. Indeed, fast transfers require high-bit rate connections, and grid operation requires network predictability and high availability. On the other hand, the Internet historical technology is not naturally best suited to deterministic behaviour. In this part, we will explain the technical challenges and the range of options available to improve QoS guarantees in Internet-based networks.

Not only the underlying network has to be highly performing, but the network software running within the end-systems must have an optimal behaviour. This part recalls the basics of TCP and discusses the relationships between TCP and the risks of congestions over Internet-based connections.

The Grid is not only a network of computer resources but also a network of people cooperating to use these resources. Part of the collaborative tools scientists are increasingly using include audio and video systems. They place new challenging requirements on the networking systems. We will discuss in this part these requirements and their consequences on the underlying network.


Internet QoS options

·          Why is QoS networking important in Grid environments?

·          Options to improve Internet QoS: reservations by signalling vs. aggregate-marking techniques

·          The NSIS and Diffserv protocols: status, prospects; are they complementary of competing technologies?

·          The role of MPLS in QoS issues

·          Are these technologies really necessary?

TCP and congestion control

·          Fundamentals of TCP mechanisms for flow and congestion control

·          The challenges of long distance / high bit rate Grid networking

·          Congestion notification principles in the Internet

·          Congestion avoidance and management: RED, ECN

·          Overall comparison of QoS and congestion management techniques

Supporting real-time steaming traffic over the Internet

·          Qualitative Requirements of real-time applications

·          Why is TCP inappropriate? The need of RTP, its functionalities

·          Quantitative requirements of audio and video streaming

·          Limiting the overheads; header compression

·          Conclusion: Which QoS technologies are suitable for real-time applications?

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