TRANSPORT and NETWORK LAYERS - Part 1Transport and Network Layers - TCP/IP (Part 1)Examples of Transport/Network Layer ProtocolsSlide 4TCP/IPSlide 6TCPTransmission Control Protocol (TCP)TCP (Continued)Slide 10Port IdentifiersInternet Protocol (IP)Slide 13IP (Continued)IPv4 Addressing ICANNIPv4 Addressing Dotted Decimal NotationIPv4 Addressing Class Based Address StructureIPv4 Addressing Network and Host AddressesIPv4 Addressing Class Participation Exercise # 1IPv4 Addressing (Continued) SubnetsIPv4 Addressing Subnet MasksSubnet mask application Determining if sender and receiver are on same subnetSubnets (Continued) Partial SubnettingSubnet Mask ApplicationsNumber of Subnets and Number of Computers Per Subnet Class C AddressesClass Participation Exercise # 2 – Question # 5TRANSPORT and NETWORK LAYERS - Part 1 Dr. V.T. RajaOregon State UniversityTransport and Network Layers - TCP/IP (Part 1) Chapter Objectives:•Understand primary functions of transport and network layers •Understand the “big picture” –Five-layer network modelExamples of Transport/Network Layer Protocols•Examples:–Two popular transport/network layer protocols–Another example of protocol in a WAN environment that is not popular in North America–Protocol for IBM compatible hardware/software and mainframe environmentsExamples of Transport/Network Layer Protocols•Examples:–Two popular transport/network layer protocols•TCP/IP•IPX/SPX–Another example of protocol in a WAN environment that is not popular in North America•X.25–Protocol for IBM compatible hardware/software and mainframe environments•SNA•APPNTCP/IP•Why TCP/IP?•What is the expansion of TCP/IP?•What are the major functions of TCP/IP?TCP/IP•Why TCP/IP?–Most widely used protocol on Internet•Estimated about 70-80% of LAN, MAN, and backbone networks use TCP/IP–Reliable protocol•TCP/IP performs some error detection/error correction functions, although this is not a primary function of the network layer protocol–Compatible with many data link protocols•What is the expansion of TCP/IP?–Transmission Control Protocol/Internet Protocol •What are the major functions of TCP/IP?–Packetizing, Addressing and RoutingTCP•Main functions of TCP: Packetizing–What is Packetizing?•At sender•At final destination•Thought Questions (with regard to the “big picture”):–With what layer(s) does TCP interface in the 5-layer model?–If more than two computers are involved in message transmission, then is TCP involved in all the computers? In how many computers is TCP involved?Transmission Control Protocol (TCP)•Main function of TCP:–Packetizing – What is packetizing?•At sender–Break messages into packets–Assign packet numbers•At final destination–Check if all packets have arrived–Reassemble packets–Interfacing with two other layers•Thought Questions (with regard to the “big picture”):–With what layer(s) does TCP interface in the 5-layer model?–If more than two computers are involved in message transmission, then is TCP involved in all the computers? In how many computers is TCP involved?TCP (Continued)•Some details on TCP header:–TCP header containing 24 bytes (192-bit header) of overhead information is enclosed along with user’s data:•Examples of overhead information added:–Source and destination address –Packet sequence number•Thought Question (with regard to the “big picture”):–Didn’t the data link layer already have the source and destination address specified in the DLH? Is TCP duplicating this function of DL?Token Ring and Ethernet Frames Start Frame Destination Source Message End delimiter control address address variable delimiterToken Ring formatAccess Framecontrol check sequence1 byte 4 bytesEthernet formatDestination Source Length Message CRC-32address address 2 bytes variable 4 bytes6 bytes 6 bytesPort Identifiers•Source Port IDs refer to software used at application layer of source computer•Destination Port IDs refer to software to be used at application layer of final destination computer •With TCP/IP, each application layer software has a unique port address/identifier. •Every standard application layer software on the Internet has a predefined (default) port number. •Thought Questions: –Could network managers choose not to use the default port numbers? –Why would a network manager not want to use a default port number?Internet Protocol (IP)•What are IP’s main functions? –Main functions:•Thought Question: –Is IP involved only at sender’s or final destination computers? Or is it involved in all interim computers that take part in the message routing as well?Internet Protocol (IP)•What are IP’s main functions? –Main functions:•Addressing•Routing•Thought Question: –Is IP protocol involved only at sender’s or final destination computers? Or is it involved in all interim computers that take part in the message routing as well? •IP is involved not only at source and final destination, but also involved at each of the intervening computers involved in the message transmission.IP (Continued)•Different versions of IP–IPv4 and IPv6•IP creates a IP header–IP header contains (among other overhead information) source and destination address!•Network layer (IP) address–Examples?•Thought Question (with regard to the “big picture”):–In what order are the different headers from different layers combined with the user data packet?–If DL protocol is Ethernet, and NL protocol is TCP/IP, then what is the maximum packet size for user data? Assume DLH and DLT sizes sum to 26 bytes, TCP header size is 24 bytes, and IP header size is 24 bytes as well. –Sample content in each header?IPv4 AddressingICANN•Every computer participating on the Internet should use approved network layer (IP) addresses. •IP Addresses are approved by ICANN or one of several private companies authorized by ICANN–Internet Corporation for Assigned Names and Numbers– http://www.icann.org/–FAQ on registration of IP addresses –http://www.internic.net/faqs/IPv4 AddressingDotted Decimal Notation•Dotted Decimal Notation•Four bytes (8 bits = 1 byte) per address•Each byte separated by a dot•Each byte expressed in decimal