1. Lecture 12 Internet Protocols Internet resource allocation and QoS
IPv4 versus IPv6
UDP
TCP
Internet resource allocation and QoS

2. Projects and midterm
Progress report Monday February 25, 8 AM from all individuals or groups. Hard Deadline!!
Midterm: Tuesday, February 26, 7-7:30 PM.
Material – Chapters 1,2, and 4 including today’s lecture.
Open book.
3 questions: 30 minutes

4. IPv4

5. IPv6

6. UDP

7. TCP Supports: Error control. For each segment: Flow Control
Sequence numbers.
Acknowledgment.
Timeout
Example – stop and wait protocol. Very inefficient.
Window based
Flow Control
Congestion Control

9. TCP

10. TCP 1 bit flags ACK – when set the ack value is valid
SYN, RST, FIN – used for connection establishment and tear-down
PUSH – data should be passed to the upper layer immediately.
URG – there is urgent information in the data

11. Data streaming. MSS- maximum segment size

12. TCP flow control window

14. TCP is a connection-oriented protocol for client-server communication

16. TCP congestion control
Host centric, feedback-based resource allocation policy.
The congestion control window is affected by the timing of the acknowledgments. A late or missing acknowledgment signals that the network is congested.

18. Other Internet protocols
ICMP – used by hosts and routers to exchange network layer information, e.g., error reporting
RIP – Routing Information Protocol
OSPF – Open Shortest Path First Protocol

19. Internet traffic TCP  90 – 95 % of the Internet traffic
65-75 % of TCP traffic is Web related
10 % of TCP traffic is due to News
5 % of TCP traffic is due to
5 % of TCP traffic is due to FTP
1 % of TCP traffic is due to Napster
UDP  5 – 10 % of the Internet traffic
DNS
Realaudio
games

20. Flows and resource allocation
Flow: sequence of packets with a common characteristics
A layer-N flow  the common attribute a layer-N attribute
All packets exchanged between two hosts  network layer flow
All packets exchanged between two processes  transport layer flow