CNT 4513 Study Guild
Note: This study guild also include the material covered before midterm for completeness. You can focus on Chapter 4 and 5

Chapter 1
1. Internet: largest system of interconnected computer networks
a) Network edge: end system and access network
b) Network core: packet switching(vs. circuit switching)
2. Network Performance
a) Delay: Processing delay, queuing delay, transmission delay, propagation delay
b) Throughput: bottleneck link
3. Protocol layers
a) application (message), transport (segment), network (datagram), link (frame), physical layer
b) Layer implementation, data encapsulation
Chapter 2
1. Architecture
a) client-server: dedicated servers, fixed IP, not scalable, single-point-of-failure. (E.g., Web, FTP, Telnet, and e-mail)
b) p2p: direct communication between peers, self-scalability. (E.g., BitTorrent, Skype, PPstream)
2. Process communication
Socket: interface between application process and underlying transport layer infrastructure
Datagram socket (connectionless socket for UDP)
Stream socket (connection-oriented socket for TCP)
3. Web and HTTP
Web page: base HTML file + referenced objects
URL: hostname + object’s path name
HTTP: request-response protocol , TCP, , stateless, message format, non-persistent vs. persistent connections
Cookie: back-end database at web site, cookie file in client site, cookie header line in response and request message
Web caching: proxy server, conditional get
4. FTP
Control connection and data connection (out-of-band), TCP
Maintain state about the user
FTP commands and replies
5. Email
User agents, mail servers
SMTP: TCP, stateful, push protocol, multiple objects can be placed in one message
Mail Access Protocols: POP3 (maintain state within session, but not across sessions), IMAP (allows folder functions, maintain states across sessions), Web-based E-mail (HTTP)
6. DNS
Service: translate host name to IP, host aliasing, mail server aliasing
Implementation: distributed, hierarchical database (root, top-level domain, authoritative DNS), use UDP
DNS query: iterative query, recursive query
DNS caching
Chapter 3
1. Transport-layer service: communication between process to process
2. Multiplexing and demultiplexing
UDP socket: destination IP and port, multiple clients can communicate with a single UDP socket
TCP socket: welcome socket + separate connection socket for each client, four tuple information to identify a socket
3. Checksum to detect errors
4. Reliable data transfer
Acknowledgement, timeout, retransmission, sequence number
Stop-and-wait vs. pipelining (sliding window)
GBN: cumulative ack, resend all packets without acks (receiver doesn’t buffer out-of-order packets)
SR: individual ack, resend a single packet each time (receiver buffers out-of-order packets)
5. UDP
Connectionless (no connection state), best-effort, unreliable data transfer
Segment structure
6. TCP
TCP segment structure: seq and ack number, rwnd, flag filed (SYN, FIN)
Connection management: setup and tear down
Reliable data transfer: cumulative ack, resend a single packet each time, seq number for counting data bytes (fast retransmit, delayed ack)
Flow control: receive window size
Timeout calculation

Chapter 4
4.1 Network-layer services: Forwarding and routing
Virtual circuit: connection
4.2.2 Datagram networks: connection-less, best-effort

4.4 IP addressing: CIDR vs. Classful addressing, longest prefix match(I forgot to mention this in class)
IP datagram format (IPv4 vs. IPv6) DHCP: DHCP discover, offer, request, ACK (four broadcasting UDP packets) NAT: private addresses ICMP: ping, traceroute, discover MTU
4.5 Intra-Domain Routing algorithms
RIP: distance vector
OSPF: link state
4.6 Inter-Domain Routing
BGP: eBGP, iBGP
Attributes: AS-PATH, NEXT-HOP
Routing policy
Chapter 5
5.1 Link-layer services
5.3 Multiple Access Protocols
5.4 MAC addresses and ARP
Ethernet
Switch: filtering and forwarding, Self-learning