© NOKIADEFAULT.PPT / 22.08.1997 / AO page: 1 IP in LANs.

© NOKIA DEFAULT.PPT / 22.08.1997 / AO page: 1

IP in LANsIP in LANs


LAN TechnologiesLAN Technologies

• Ethernet - 10 Mbps, 100Mbps Fast Ethernet, Gigabit Ethernet

• Cable TV LANs

• Wireless LANs

• Token Ring, Token Bus

• FDDI

• ATM LANE, MPOA


Ethernet PrinciplesEthernet Principles

• Originally utilized shared media

• Operates on almost any media:

• IEEE 802.3 physical layer specifications• 10BASE5 Thick Coax

• 10BASE2 Thin Coax

• 10BASE-T Twisted Pair

• 10BROAD35 CATV wire

• 10BASE-F Fibers


Ethernet medium specifications Ethernet medium specifications

• 10BASE5, 0.5" coax bus

• transceiver and drop cable required

• Max length of the bus is 500 meters


Ethernet Medium Specifications - contEthernet Medium Specifications - cont

• 10BASE2, 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



• 10BASE-T twisted pair cable

• Hosts connected to a HUB

• At present most popular installation



• 10BASE-F Fibers especially used between HUBs and LAN core

• 2km link length in Point-to-Point connections

• A pair of fibers needed for single link - one for transmission and other for receiving

• Star topology: Up to 33 stations with 1 km link length

•


Ethernet IEEE 802.3 frame formatEthernet 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) |+-------------+--------+----------------------+------------------+-----------+--------------+---+---------+


Ethernet CSMA/CDEthernet 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 re-start algorithm

• Min. packet size and max. link length defined so that collisions detected


Ethernet LAN architectureEthernet LAN architecture

• Bridge - a transparent layer 2 device that interconnects several segments

• Many benefits

• Security

• Performance

• Reliability

• Structure


Ethernet HubsEthernet Hubs

• 10BASET twisted pair from host to hub

• Usually Fiber link from hub to LAN backplane

• Better structureand security

• easier to install and maintain


Ethernet SwitchingEthernet Switching

• Switching HUB - a HUB operating like learning bridge

• FIFO-buffered backplane bus: Hub is able to transmit several frames through the hub concurrently

• Usually dual-speed: Configurable 10Mbps and 100Mbps ports

• Dedicated 10Mbps


Ethernet SwitchingEthernet Switching

• Ethernet Switches used increasingly to replace routers

• Switching much faster than routing

• Also Routing Switches available that combine Router and Switch functionality

• Route once, switch following frames


Address Resolution ProtocolsAddress Resolution Protocols

• Underlying network is not aware of IP

• ARP used to bind IP addresses to MAC addresses

• RFC826: 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


DHCPDHCP

• Used for similar operation as RARP

• Supports three IP address mechanisms:

• automatic

• dynamic

• manual

• Decreases amount of IP-addresses needed in LAN


DHCP - contDHCP - cont

• Messages:

• DHCPDISCOVER - Client broadcast to locate available servers.

• DHCPOFFER - Server to client in response to DHCPDISCOVER with offer of configuration parameters.

• 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.


applied ARP usageapplied 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

• 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


LAN development and marketsLAN development and markets

• 100 Mbps Fast Ethernet, included in IEEE 802.3

• compatible with 10Mbps Ethernet

• compatible with 10Mbps Cabling

• link lengths reduced

• Gigabit Ethernet, IEEE 802.3z standardization in process

• especially to be used on fiber links

• LAN backplane

• Compatible with 10Mbps frames


MarketsMarkets

1.1.1 Revenue and Shipments of Shared Media Hubs to Worldwide (Dataquest 08/97)

1997 1998 1999 2000 2001 CAGR1997-2001

Ports Shipped (K) 72864,8 76563 76211,8 75030,6 73604 0,2 %Shipment Growth 16,1 % 5,1 % -0,4 % -1,5 % -1,9 %Average end-user price (USD) 66,4 55,6 48,6 46,1 46,1 -6,9 %End-user revenue (USD M) 4835,8 4258,7 3703,4 3458,9 3390,5 -6,7 %Revenue growth 3,2 % -11,9 % -13,0 % -6,6 % -2,0 %

1.1.1 Worldwide shared media hub market split by technology (Datamonitor, 07/97)

(USD) 1995 1996 1997 1998 1999 2000 200110Mbps Ethernet 3800 4020 4330 4490 4580 4420 4200100 Mpbs Ethernet 240 380 460 540 620 680 700Token Ring 730 630 480 350 260 200 150Other (incl. FDDI) 180 250 330 390 430 410 350TOTAL 4950 5280 5600 5770 5890 5710 5400


LAN MarketsLAN Markets

1.1.1 Worldwide LAN switch market split by technology, 1995-2001 (Datamonitor,07/97)

USD millions 1995 1996 1997 1998 1999 2000 2001 ATM 140 340 650 1 020 1 340 1 700 2 000 10Mbps Ethernet 1 080 2 480 3 430 4 150 4 370 4 400 4 450 100Mbps Ethernet 80 240 610 1 350 2 700 3 900 5 100 Gigabit Ethernet 0 0 50 200 450 950 1 700 Token ring 100 260 450 600 600 550 450 IP / L3 switching 0 0 60 200 420 800 1 150 Other 100 200 330 400 450 400 350

Total 1 500 3 520 5 580 7 920 10 330 12 700 15 200

© NOKIADEFAULT.PPT / 22.08.1997 / AO page: 1 IP in LANs.

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Transcript of © NOKIADEFAULT.PPT / 22.08.1997 / AO page: 1 IP in LANs.