IP in LANs NOKIA DEFAULT PPT 22 08

IP in LANs © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 1

LAN Technologies • • • Ethernet - 10 Mbps, 100 Mbps Fast Ethernet, Gigabit Ethernet Cable TV LANs Wireless LANs Token Ring, Token Bus FDDI ATM LANE, MPOA © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 2

Ethernet Principles • Originally utilized shared media • Operates on almost any media: • IEEE 802. 3 physical layer specifications • • • © NOKIA 10 BASE 5 Thick Coax 10 BASE 2 Thin Coax 10 BASE-T Twisted Pair 10 BROAD 35 CATV wire 10 BASE-F Fibers DEFAULT. PPT / 22. 08. 1997 / AO page: 3

Ethernet medium specifications • • • 10 BASE 5, 0. 5" coax bus transceiver and drop cable required Max length of the bus is 500 meters © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 4

Ethernet Medium Specifications - cont • • 10 BASE 2, thin 0. 25" coax Hosts are connected directly to the thin coax bus Bus max. 200 meters long susceptible to any faults in the cable or hosts' network equipment © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 5

Ethernet Medium Specifications - cont • • • 10 BASE-T twisted pair cable Hosts connected to a HUB At present most popular installation © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 6

Ethernet Medium Specifications - cont • • • 10 BASE-F Fibers especially used between HUBs and LAN core • • Star topology: Up to 33 stations with 1 km link length 2 km link length in Point-to-Point connections A pair of fibers needed for single link - one for transmission and other for receiving © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 7

Ethernet IEEE 802. 3 frame format • • • Ethernet is connectionless, frame exchange protocol Each station has unique 6 octet long address Frame Size • • max. 1518 octets min 512 bits +-------+----------------------+-------+-------+---------+ |Preamble(7)|SFD(1)|Destination addr(6)|Source addr (6)|Length(2)|Data(<1500)|Pad|CRC(4) | +-------+----------------------+-------+-------+---------+ © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 8

Ethernet CSMA/CD • • • IEEE 802. 3 Medim Access Control (MAC) CSMA/CD Carrier Sense Multiple Access / Collision Detection Fairly simple algorithm: • • • Listen to the network - wait until media is free Wait interframe gap time If still free, start sending - simultaneously monitor received signal If collision is detected, transmit jam sequence, wait random time and restart algorithm Min. packet size and max. link length defined so that collisions detected © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 9

Ethernet LAN architecture • • Bridge - a transparent layer 2 device that interconnects several segments Many benefits • • © NOKIA Security Performance Reliability Structure DEFAULT. PPT / 22. 08. 1997 / AO page: 10

Ethernet Hubs • • 10 BASET twisted pair from host to hub Usually Fiber link from hub to LAN backplane Better structureand security easier to install and maintain © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 11

Ethernet Switching • • Switching HUB - a HUB operating like learning bridge • • Usually dual-speed: Configurable 10 Mbps and 100 Mbps ports FIFO-buffered backplane bus: Hub is able to transmit several frames through the hub concurrently Dedicated 10 Mbps © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 12

Ethernet Switching • • • Ethernet Switches used increasingly to replace routers Switching much faster than routing Also Routing Switches available that combine Router and Switch functionality • © NOKIA Route once, switch following frames DEFAULT. PPT / 22. 08. 1997 / AO page: 13

Address Resolution Protocols • • Underlying network is not aware of IP ARP used to bind IP addresses to MAC addresses RFC 826: ARP protocol for Ethernet ARP Solves MAC addresses by broadcasting a ARP request: • • • source IP address source MAC address destination IP address empty space for destination MAC address Reverse ARP - diskless host wants to know its IP address © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 14

DHCP • • Used for similar operation as RARP Supports three IP address mechanisms: • • automatic dynamic manual Decreases amount of IP-addresses needed in LAN © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 15

DHCP - cont • Messages: • • DHCPDISCOVER - Client broadcast to locate available servers. • DHCPREQUEST - Client broadcast to servers requesting offered parameters from one server and implicitly declining offers from all others. • DHCPACK - Server to client with configuration parameters, including committed network address. • DHCPNAK - Server to client refusing request for configuration parameters (e. g. , requested network address already allocated). • DHCPDECLINE - Client to server indicating configuration parameters (e. g. , network address) invalid. • DHCPRELEASE - Client to server relinquishing network address and cancelling remaining lease. © NOKIA DHCPOFFER - Server to client in response to DHCPDISCOVER with offer of configuration parameters. DEFAULT. PPT / 22. 08. 1997 / AO page: 16

applied ARP usage • A Proxy-host that is attached to LAN and replies to ARP request targeted to hosts attached behind the Proxy • can be utilized • • • © NOKIA in simple Firewalls to create private local sub-net without need to allocate "real" IP-addresses by a host that tunnels IP packets through some other network technology DEFAULT. PPT / 22. 08. 1997 / AO page: 17

LAN development and markets • 100 Mbps Fast Ethernet, included in IEEE 802. 3 • • compatible with 10 Mbps Ethernet compatible with 10 Mbps Cabling link lengths reduced Gigabit Ethernet, IEEE 802. 3 z standardization in process • • • © NOKIA especially to be used on fiber links LAN backplane Compatible with 10 Mbps frames DEFAULT. PPT / 22. 08. 1997 / AO page: 18

Markets © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 19

LAN Markets © NOKIA DEFAULT. PPT / 22. 08. 1997 / AO page: 20