ECEN “Internet Protocols and Modeling” Course Materials: Papers, Reference Texts: Bertsekas/Gallager, Stuber, Stallings, etc Grading (Tentative): HW: 20%, Projects: 40%, Exam-1:20%, Exam-II:20% Lecture notes and Paper Reading Lists: available on-line: TBA Class Website: Research Interests and Projects: URL: Instructor: Professor Xi Zhang Office: WERC 331 Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP Closed-loop flow control and “ Self-Clocking ” Principle-1 Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP Closed-loop flow control and “ Self-Clocking ” Principle-2 Sender sends packets back-to-back to receiver The vertical line is bandwidth The horizontal line is time Each of shaded box is a packet Bandwidth * Time = Bits, and so the area of each box is the packet size. The number of bits doesn ‘ t change as a packet goes through the network so a packet squeezed into the smaller long-haul bandwidth must spread out in time. Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP Closed-loop flow control and “ Self-Clocking ” Principle-3 The time Pb represents the minimum packet spacing on the slowest link in the path (the bottleneck). As the packets leave the bottleneck for the destination net, nothing changes the inter packet interval so on the receiver ’ s net packet spacing Pr = Pb. If the receiver processing time is the same for all packets, the spacing between ACKs on the receiver ’ s net Ar = Pr = Pb. Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP Closed-loop flow control and “ Self-Clocking ” Principle If the time slot Pb was big enough for a packet, it ’ s big enough for an ACK so the ACK spacing is preserved along the return path. Thus the ACK spacing on the sender ’ s net As= Pb. So, if packets after the first burst are sent only in response to an ACK, the sender ’ s packet spacing will be exactly match the packet time on the slowest link in the path – > “ Self-Clocking ” is achieved. Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Two versions of TCP Protocols TCP-tahoe (Jacobson, 1988) –Time-out based protocol - use timeout to detect packet loss and congestions TCP-reno (Jacobson, 1990) –Triple-ACK and time-out based - Use triple-duplicate ACK to same sequence number and timeouts to detect packet loss and congestions –Use fast retransmissions and fast recovery Skip Slow Start phase Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP-tahoe Protocol Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP-reno Protocol Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

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TCP protocol control variable mBandwidth: m in packets/sec, Service time: 1/m Round Trip Time (RTT): T sec Buffer size: B in packets Path pipeline capacity: Wpipe = m*T+B+1 Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP/IP Layers: 5-Layer Protocol Model 1) Physical layer 2) Network access layer 3) Internet layer 4) Host-to-host, or transport layer 5) Application layer Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP/IP Physical Layer Covers the physical interface between a data transmission device and a transmission medium or network Physical layer specifies: –Characteristics of the transmission medium –The nature of the signals –The data rate –Other related matters Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP/IP Network Access Layer Concerned with the exchange of data between an end system and the network to which it's attached Software used depends on type of network –Circuit switching –Packet switching (e.g., X.25) –LANs (e.g., Ethernet) –Others Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP/IP Internet Layer Uses internet protocol (IP) Provides routing functions to allow data to traverse multiple interconnected networks Implemented in end systems and routers Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP/IP Host-to-Host, or Transport Layer Commonly uses transmission control protocol (TCP) Provides reliability during data exchange –Completeness –Order Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP/IP Application Layer Logic supports user applications Uses separate modules that are peculiar to each different type of application Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Protocol Data Units (PDUs) Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

TCP Header Format Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

IP Header Format-1: IPv4 Header Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

IP Header Format-2: IPv6 Header (Newer Version since 1995) Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Common TCP/IP Applications Simple mail transfer protocol (SMTP) –Provides a basic electronic mail facility File Transfer Protocol (FTP) –Allows files to be sent from one system to another TELNET –Provides a remote logon capability Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Service Access Point (SAP) under TCP/IP Concepts Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Internetworking Terms Communication network – facility that provides a data transfer service among devices attached to the network Internet – collection of communication networks, interconnected by bridges/routers Intranet – internet used by an organization for internal purposes –Provides key Internet applications –Can exist as an isolated, self-contained internet Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Internetworking Terms End System (ES) – device used to support end-user applications or services Intermediate System (IS) – device used to connect two networks Bridge – an IS used to connect two LANs that use similar LAN protocols Router - an IS used to connect two networks that may or may not be similar (such as WAN and LAN) Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Functions of a Router Provide a link between networks Provide for the routing and delivery of data between processes on end systems attached to different networks Provide these functions in such a way as not to require modifications of the networking architecture of any of the attached sub- networks Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

An Example of Router Applications Prof. Xi ZhangECEN 619, Internet Protocols & Modeling

Network Differences Routers Must Accommodate Addressing schemes –Different schemes for assigning addresses Maximum packet sizes –Different maximum packet sizes requires segmentation Interfaces –Differing hardware and software interfaces Reliability –Network may provide unreliable service Prof. Xi ZhangECEN 619, Internet Protocols & Modeling