Whirlwind Tour Of Lectures So Far a.k.a. Review Athula Balachandran Wolfgang Richter

Lecture 1 : Introduction What is a network? What is the objective of a network? Building blocks of a network Sharing resources Internet vs inter-net Challenges of Internet

Lecture 2: Protocol Stacks Layering Protocols Hourglass model of the Internet IP is the compatibility layer Current Internet design goals and decisions Minimalist approach Dumb network - IP provides minimal functionality (addressing, forwarding, routing) Smart end points – Transport layer performs sophisticated functionalities

Lecture 3: Application Layer Examples Client Server model Services that applications need Tolerance to data loss Timing Bandwidth FTP HTTP Delay, Throughput Delay + Size/Throughput

Programming: Sockets getaddrinfo() - Prepare to launch! socket() - Get the file descriptor! bind() - Which port am I on? listen() - Will someone please call me? connect() - Hey, you! accept() - Thank you for calling port 8080! send() and recv() - Talk to me, please! close and shutdown() - Get out!

Lecture 4: Physical Layer Information transfer is a physical process Modulation techniques Bandwidth Nyquist Limit Capacity of Noisy Channel (Shannon's Theorem) Multiplexing – FDM, TDM, WDM

Lecture 6: Coding and Error Control Encoding (signals to bits) NRZ, NRZI, Manchester... Framing (bit stream to packets) Ethernet Framing, Clock-based framing Packet Loss and Corruption Error Coding – Parity Checking, CRC, Hamming distance Flow Control – Stop and Wait, Window based

Lecture 7: Data Link and Ethernet Media Access Control Aloha, Ethernet MAC (Exponential backoff) Collision detection → Minimum packet length Ethernet Packet headers (what is the purpose of the fields?) Ethernet addresses

Lecture 8: Bridging and Switching Building larger LANs using bridges Learning bridges Spanning tree bridges Internetwork Routers to forwarding packets Choices : Virtual Circuits, Source Routing, Global Addresses

Lecture 9: IP Addressing IP forwarding - global addressing, alternatives, lookup tables IP addressing - hierarchical, CIDR IP service - best effort, simplicity of routers IP packets - header fields, fragmentation ICMP

Lecture 10: Ipv6 and NAT IPv6 NAT Clients Servers? Port mapping

Lecture 11: Intra-domain routing How to generate forwarding tables? Distance Vector Link State Routing Hierarchy

Lecture 12: Inter-domain Routing BGP designed to: Provide hierarchy that allows scalability Allow enforcement of policies related to structure Wide area Internet structure and routing driven by economic considerations Customer, providers and peers Tier 1, Tier 2, Tier 3 ISPs Valley-free routing Mechanisms Path vector – scalable, hides structure from neighbors, detects loops quickly

Lecture 13: DNS Motivations à large distributed database Scalability Independent update Robustness Hierarchical database structure Zones How is a lookup done Caching/prefetching and TTLs

Lecture 14: Router Design Modern network data rates are much too fast for conventional processors and multiple interface cards on a bus Partition work into: Examine header, make decisions Move the bits Parallelism is essential Line cards process incoming packets on each input Switch fabric complex but avoids bottleneck Caching and other optimizations needed and possible for common cases