IP - Internet Protocol No. 1  Seattle Pacific University IP: The Internet Protocol Kevin Bolding Electrical Engineering Seattle Pacific University

IP - Internet Protocol No. 2  Seattle Pacific University Internet Protocol IP is by far the most common networking protocol Used to connect thousands of local internetworks together IP is a network layer protocol, and is built on top of a data-link and physical layer protocol Transport Network Data Link Physical ODI/NDIS NIC Driver NIC/Media TCPUDP IP ARPOSPFRIP ICMP

IP - Internet Protocol No. 3  Seattle Pacific University Datagrams Information to transmit may be anything from short messages to continuous streaming contents IP is a packet-switching network Maximum size of message that may be sent in one datagram Each datagram must be 64KB or less Long (or continuous) messages must be broken into many datagrams and sent separately Breaking messages into datagrams and reassembling them is the job of a Transport Layer Protocol TCP (Transmission Control Protocol) makes long messages appear continuous to the application UDP (User Datagram Protocol) provides less support, but is more lightweight and faster in some situations

IP - Internet Protocol No. 4  Seattle Pacific University The Multi-Layer Process Reading a web page at facebook.com using a browser 1. Browser asks TCP to open a connection with assigns a TCP session number (ex: 1432) 2. facebook.com asks TCP to send the web page data using session fackbook.com’s TCP sends components using datagrams in IP, each tagged with session number 1432 Components 64KB are split into multiple datagrams 4. IP passes the data through the network using routers 5. Your computer’s TCP client receives packets and reassembles them 6. Web page contents are delivered to your browser

IP - Internet Protocol No. 5  Seattle Pacific University IPv4 Header Version Header Length Type of Service Total Length (bytes) Identification Flags Fragment Offset Time to Live Protocol Header Checksum Source Address Destination Address Options + Padding 32 bits 20 bytes minimum

IP - Internet Protocol No. 6  Seattle Pacific University IPv4 Addressing Each IP address is 32 bits long 4 groups of 8 bits Each group can have numbers and 255 are reserved for broadcast Groups to the left specify the network, others the host Network address is assigned by InterNIC Class A: Network.host.host.host Network is from 1-126, allows up to 16,000,000 hosts Class B: Network.network.host.host Network begins with 128 to 191, allows up to 64,000 hosts Class C: Network.network.network.host Network begins with , allows up to 254 hosts

IP - Internet Protocol No. 7  Seattle Pacific University The IP problem We’re running out of IP addresses Solution A: Bigger IP bit address (IPv6) In the meantime 32 bits - 4 billion addresses ought to do… Squeezing the most out of the bits Private networks can have duplicate addresses 10.x.x.x, x.x to x.x, x to x Classless Inter-Domain Routing (CIDR) Forget classes, allow the number of network bits to be assigned as desired (ex: /18 is between B and C size) Dynamic Host Configuration Protocol (DHCP) DHCP server maintains a list of available IP addresses Computers request IP address from DHCP server IP address is leased for a fixed amount of time; recycled

IP - Internet Protocol No. 8  Seattle Pacific University IPv6 Header Version Traffic Class Flow Label Payload Length Source Address 128-bit Destination Address 128-bit 32 bits 40 bytes minimum Next Header Hop Limit Note: Land area of earth = 2 47 m 2 --> 2 81 = addresses/m 2

IP - Internet Protocol No. 9  Seattle Pacific University Interface to Lower Layers What does an Ethernet (or other Data-Link Layer network) do with an IP message? Ethernet uses MAC addresses for routing IP address is nice, but useless ARP - Address Resolution Protocol Router/Host broadcasts an ARP Request Contains the IP address of desired destination Host with matching IP address responds ARP Reply broadcasts MAC address Caching Routers generally cache IP-to-MAC translations Need to refresh every now and then

IP - Internet Protocol No. 10  Seattle Pacific University IP Summary Network-layer protocol Used from LANs to The Internet Routers are the key Still going strong Basic form (IPv4) has been given new life CIDR, private networks DHCP allows it to work with rapidly changing networks (I.e. laptops) The future IPv6 is coming… Bigger addresses, better addresses