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

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

IPv4

IPv6

UDP

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

TCP

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

Data streaming. MSS- maximum segment size

TCP flow control window

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

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.

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

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 Email 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

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