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Internet Protocol. Internetworking Lab I. Internet Protocol - IP. Internet Collection of networks. Internet Protocol - IP. Internet Collection of networks. Internet Protocol - IP. Mac Addresses are specific to Ethernet devices
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Internet Protocol Internetworking Lab I
Internet Protocol - IP • Internet • Collection of networks
Internet Protocol - IP • Internet • Collection of networks
Internet Protocol - IP • Mac Addresses are specific to Ethernet devices • Other technologies use different kinds of physical addresses • As a result, MAC addresses do not suffice for addressing on an internet • ALSO MAC addresses carry no information about the location of a device do not help in the routing of frames
Internet Protocol - IP • Goal • Single seamless communication system • HIDE details of the physical network • Required • Layer providing transparency from underlying • Network • Protocols • Forward packet from network to network • Addressing to recognize location of network
Internet Protocol - IP • Uniformity • Across technologies • Across different network topologies • To communicate across networks • without knowing hardware address • Solution • IP layer • IP addressing
IP Addresses 32 bits or 4 bytes dotted quad notation: 129.21.21.3 each number is in the range 0…255 each fits precisely into 1 byte (8 bits) Two parts network id and host id two “dimensions” help in routing packets on the network
Classes of IP Addresses Class A network id is 1st byte of the dotted quad host id is the remaining 3 bytes Class B network id is 1st two bytes host id is remaining two bytes Class C network id is 1st three bytes host id is remaining byte Classes D and E - special cases
IP Addresses The network mask (subnet mask) where there are 1’s indicates the network ID where there are 0’s indicates the host ID Examples for a class A address: 255.0.0.0 for a class B address: 255.255.0.0 for a class C address: 255.255.255.0
IP delivery • Unreliable - delivery not guaranteed • Connectionless -packet independence • Best Effort Delivery - only discard for a reason • Fragmentation
IP delivery • Unreliable - delivery not guaranteed • Connectionless -packet independence • Best Effort Delivery - only discard for a reason • Fragmentation
IP delivery • Version field - 4bits • the current version of IP is 4 (IPv4) • Hlen field - 4bits • specifies the length of the header • TOS (type of service) field - 8 bits • how packet should be handled • not widely used • Length field - 16 - measured in octets • specifies the length of the datagram
IP delivery • Identification • used to determine which fragments belong to each other • Flag • indicates how the fragmentation process will be handled • Fragment offset • indicates where a fragment belongs in the complete message
IP delivery • TTL (time to live) field • more of a hop count rather than a timer • Protocol field • identifies the higher-level protocol • Checksum field • checks an error in the header • Source and Destination addresses
IP delivery • TTL (time to live) field • more of a hop count rather than a timer • Protocol field • identifies the higher-level protocol • Checksum field • checks an error in the header • Source and Destination addresses