Summary of mac protocols o What do you do with a shared media? o Channel Partitioning by time, frequency or code Time Division, Code Division, Frequency Division o Random partitioning dynamic) ALOHA, S-ALOHA, CSMA, CSMA/CD carrier sensing: easy in some technoligies(wire), hard in others(wireless) CSMA/CD used in Ethernet o Taking Turns polling from a central cite, token passing 5: DataLink Layer 5a-1
5: DataLink Layer 5a-1 Summary of MAC protocols What do you do with a shared media? Channel Partitioning, by time, frequency or code • Time Division,Code Division, Frequency Division Random partitioning (dynamic), • ALOHA, S-ALOHA, CSMA, CSMA/CD • carrier sensing: easy in some technoligies (wire), hard in others (wireless) • CSMA/CD used in Ethernet Taking Turns • polling from a central cite, token passing
LAN technologies Data link layer so far: o services, error detection/correction, multiple access Next: LAN technologies o addressing o Ethernet o hubs, bridges, switches 802.11 user hosts O PPP Server O ATM Interne user hosts 5: DataLink Layer 5a-2
5: DataLink Layer 5a-2 LAN technologies Data link layer so far: services, error detection/correction, multiple access Next: LAN technologies addressing Ethernet hubs, bridges, switches 802.11 PPP ATM
LAN Addresses and aRp 32-bit IP address: 口 network- ayer address O used to get datagram to destination network (recall IP network definition) LAN (or MAC or physical)address O used to get datagram from one interface to another physically-connected interface(same network) 0 48 bit MaC address for most LaNs) burned in the adapter rom 5: DataLink Layer 5a-3
5: DataLink Layer 5a-3 LAN Addresses and ARP 32-bit IP address: network-layer address used to get datagram to destination network (recall IP network definition) LAN (or MAC or physical) address: used to get datagram from one interface to another physically-connected interface (same network) 48 bit MAC address (for most LANs) burned in the adapter ROM
LAN Addresses and ARP Each adapter on Lan has unique LAN address 1A-23F9-CD-06-9日 dapter node LAN 5C-66AB90-75-B1 88-日22F-54-1A0F 49-BD-D2C7-56-2A node 5: DataLink Lo 5a-4
5: DataLink Layer 5a-4 LAN Addresses and ARP Each adapter on LAN has unique LAN address
LAN Address(more) O MAC address allocation administered by ieee o manufacturer buys portion of mac address space (to assure uniqueness) 口 analogy: (a)MAC address: like Social Security Number (b)IP address: like postal address o MaC flat address = portability o can move lan card from one lan to another o IP hierarchical address not portable o depends on network to which one attaches 5: DataLink Layer 5a-5
5: DataLink Layer 5a-5 LAN Address (more) MAC address allocation administered by IEEE manufacturer buys portion of MAC address space (to assure uniqueness) Analogy: (a) MAC address: like Social Security Number (b) IP address: like postal address MAC flat address => portability can move LAN card from one LAN to another IP hierarchical address NOT portable depends on network to which one attaches