Chap 9 TCP/IP Andres, Wen-Yuan Liao Department of Computer Science and Engineering De Lin Institute of Technology

Overview TCP/IP operation TCP/IP operation TCP/IP protocol stack component TCP/IP protocol stack component Reliable and unreliable transport layer protocols Reliable and unreliable transport layer protocols ICMP/ARP/RARP ICMP/ARP/RARP

The TCP/IP Protocol Suite TCP/IP protocols & the OSI model TCP/IP protocols & the OSI model The application layer The application layer The transport layer The transport layer TCP and UDP segment format TCP and UDP segment format Port numbers Port numbers Three-way handshake Three-way handshake Acknowledgment & windowing Acknowledgment & windowing

TCP/IP protocols and the OSI model Defense Advanced Research Projects Agency (DARPA) Defense Advanced Research Projects Agency (DARPA) TCP/IP is the de facto standard for internetwork communications TCP/IP is the de facto standard for internetwork communications

TCP/IP  A universally available protocol  A useful reference for understanding other protocols  Be important because the router uses it as a configuration tool

TCP/IP The layers most closely affected by TCP/IP are Layer 7, Layer 4, and Layer 3 The layers most closely affected by TCP/IP are Layer 7, Layer 4, and Layer 3 Enable communication among any set of interconnected networks Enable communication among any set of interconnected networks

Application layer Supports addressing protocols and network management Supports addressing protocols and network management Has protocols for file transfer, , and remote login Has protocols for file transfer, , and remote login

translating names of domains and their publicly advertised network nodes into addresses Translate names of domains into addresses

WINS Windows Internet Naming Service Windows Internet Naming Service Microsoft-developed standard for Microsoft Windows NT that automatically associates NT workstations with Internet domain names Microsoft-developed standard for Microsoft Windows NT that automatically associates NT workstations with Internet domain names

HOSTS A file created by network administrators and maintained on servers A file created by network administrators and maintained on servers Be used to provide static mapping between IP addresses and computer names Be used to provide static mapping between IP addresses and computer names

SMTP Simple Mail Transport Protocol Simple Mail Transport Protocol Governs the transmission of e- mail over computer networks Governs the transmission of e- mail over computer networks Does not provide support for transmission of data other than plain text Does not provide support for transmission of data other than plain text

SNMP Simple Network Management Protocol Simple Network Management Protocol Provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance and security Provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance and security

FTP File Transfer Protocol File Transfer Protocol A reliable connection-oriented service that uses TCP to transfer files between systems that support FTP A reliable connection-oriented service that uses TCP to transfer files between systems that support FTP Supports bi-directional binary file and ASCII file transfers Supports bi-directional binary file and ASCII file transfers

TFTP Trivial File Transfer Protocol Trivial File Transfer Protocol A connectionless unreliable service A connectionless unreliable service Be useful in some LANs because it operates faster than FTP in a stable environment Be useful in some LANs because it operates faster than FTP in a stable environment

HTTP Hypertext Transfer Protocol Hypertext Transfer Protocol Supports the exchange of information on the WWW Supports the exchange of information on the WWW Supports many different file types, including text, graphic, sound, and video Supports many different file types, including text, graphic, sound, and video

Troubleshooting protocols Telnet Telnet PING PING Traceroute Traceroute NBSTAT NBSTAT NETSTAT NETSTAT ipconfig/winipcfg ipconfig/winipcfg

NBSTAT To troubleshoot NetBIOS name resolution To troubleshoot NetBIOS name resolution Be used to view and remove entries from the name cache Be used to view and remove entries from the name cache

NETSTAT Provides information about TCP/IP statistics Provides information about TCP/IP statistics Be used to provide information about the status of TCP/IP connections and summaries of ICMP, TCP, and UDP Be used to provide information about the status of TCP/IP connections and summaries of ICMP, TCP, and UDP

ipconfig/winipcfg View current network settings for all ip (nic) adapters on a device View current network settings for all ip (nic) adapters on a device Be used to view the MAC address, IP address, and gateway Be used to view the MAC address, IP address, and gateway

Transport layer End-to-end service (segment) End-to-end service (segment) Layer 4 data stream Layer 4 data stream  A logical connection between the endpoints of a network  Provides transport services from a host to a destination

TCP  A connection-oriented, reliable protocol  Flow control: sliding windows  Reliability: sequence numbers and acknowledgments  Re-sends/Virtual circuit  Provides guaranteed delivery

UDP Connectionless and unreliable Connectionless and unreliable Responsible for transmitting messages Responsible for transmitting messages  No software checking Advantage: speed Advantage: speed No acknowledgments/less traffic is sent/making the transfer faster No acknowledgments/less traffic is sent/making the transfer faster

Protocols using UDP TFTP TFTP SNMP SNMP Network File System (NFS) Network File System (NFS) Domain Name System (DNS) Domain Name System (DNS)

TCP and UDP port numbers Use port numbers to pass information to the upper layers Use port numbers to pass information to the upper layers Keep track of the different conversations Keep track of the different conversations Well-known port numbers Well-known port numbers

Port numbers assignment Numbers below 255 are for public applications Numbers below 255 are for public applications Numbers are assigned to companies for marketable applications Numbers are assigned to companies for marketable applications Numbers above 1023 are unregulated Numbers above 1023 are unregulated

Originating source port numbers, usually some numbers larger than 1023, are dynamically assigned by the source host

Three-way handshake Connection establishment Connection establishment  The two end stations must synchronize on each other's initial TCP sequence numbers (ISNs) Sequence numbers Sequence numbers  Track the order of packets and to ensure that no packets are lost

Simple acknowledgment and windowing To govern the flow of data between devices, TCP uses a peer-to-peer flow control mechanism To govern the flow of data between devices, TCP uses a peer-to-peer flow control mechanism

Window size The number of bytes that are transmitted before receiving an acknowledgment The number of bytes that are transmitted before receiving an acknowledgment

Acknowledgments TCP uses expectational acknowledgments, meaning that the acknowledgment number refers to the octet expected next TCP uses expectational acknowledgments, meaning that the acknowledgment number refers to the octet expected next

Sliding window The sliding The sliding  The window size is negotiated dynamically during the TCP session A larger window size allows more data to be transmitted A larger window size allows more data to be transmitted

Sequence and acknowledgment numbers Each datagram is numbered Each datagram is numbered At the receiver, TCP reassembles the segments into a complete message At the receiver, TCP reassembles the segments into a complete message If a sequence number is missing in the series, that segment is retransmitted (timeout) If a sequence number is missing in the series, that segment is retransmitted (timeout)

Layer 3 Concepts TCP/IP and the Internet Layer TCP/IP and the Internet Layer Diagram the IP datagram Diagram the IP datagram Internet Control Message Protocol (ICMP) Internet Control Message Protocol (ICMP) How ARP works How ARP works

TCP/IP & the Internet Layer  ICMP -- provides control and messaging capabilities  ARP -- IP addresses -> the data link layer address  RARP -- data link layer addresses -> network addresses

IP Header  VERS -- version number  HLEN -- header length, in 32-bit words  type of service -- how the datagram should be handled  total length -- total length (header + data)  identification, flags, frag offset -- provides fragmentation of datagrams to allow differing MTUs in the internetwork

IP Header  TTL -- Time-To-Live  protocol -- the upper-layer (Layer 4) protocol sending the datagram  header checksum -- an integrity check on the header  source and destination IP address  IP options -- network testing, debugging, security, and other options

Internet Control Message Protocol (ICMP) ICMP messages are carried in IP datagrams and are used to send error and control messages ICMP messages are carried in IP datagrams and are used to send error and control messages

How ARP works ARP is used to resolve or map a known IP address to a MAC sublayer address ARP is used to resolve or map a known IP address to a MAC sublayer address ARP cache ARP cache Local ARP Local ARP

Summary TCP/IP and OSI TCP/IP and OSI Application protocols Application protocols Transport layer Transport layer ICMP, ARP, RARP ICMP, ARP, RARP