The InternetInternet Technology2 No. 6

LAN and the Internet

Prof. Jun MuraiFaculty of Environment and Information Studies, Keio University

Local Area Network

100/1000Base-T link 1

100/1000Base-T link 2

1000Base-SX link 3

Link BLink A

LAN,WAN

Office LAN

Office LAN

Home

Wireless LAN

Base station

Optical Fiber

Internet

ISDN

ADSL

UTP

PPP

UTP

EthernetHUB/Switch

WDM

■ LAN (Local Area Network)■ WAN (Wide Area Network)

Global network

Ethernet

Kind Cable SpeedMaximum distance

Type

10BASE-2 Thin coax 10Mbps 185mBus Formed

LAN

10BASE-5 Thick coax 10Mbps 500mBus Formed

LAN

10BASE-T UTP 10Mbps 100mStar Formed

LAN

100BASE-TX UTP 100Mbps 100mStar Formed

LAN

1000BASE-T UTP 1Gbps 100mStar Formed

LAN

• Thin coax

• Thick coax

• Twisted pair (UTP cable)

CSMA/CD

• Carrier Sense Multiple Access with Collision Detection– Carrier Sense： Listen sounds

– Multiple Access：If nobody are talking, anybody can start talking

– Collision Detection：If the talk overlaps, throw the dice, wait certain time according to the number of dice, and listen sounds.

• Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)– Collision Avoidance：

Even when they can talk, they wait certain time and start talking.

Hello.Good

morningI eat.I’m leaving.

HUB / Switch

• HUB

If several ethernet cables are inserted, those will work as

an ethernet cable

– Each broadcasts’ packects will flow inside each broadcasts

• Broadcast storm

Accident that keeps flowing broadcast and causes several troubles

Keep Broadcast inside equipment and avoid affecting other segment

– Switch

• How to deliver Broadcast, being able to handle service using

Broadcast properly like DHCP

MAC Address

• MAC Address (Media Access Control address)

– Specific unique identification number allocated to each Ethernet card, which extend for connecting LAN

– Also called Hardware address

The characteristic is using different numbers for 2 same equipments

xx : xx : xx : xx : xx : xx ※ xx(00~FF)

3 byte Vendor code 3 byte Product code

6 byte

DHCP

• Dynamic Host Configuration Protocol

MAC:hoge

①Demand IP address from DHCP server

DHCP Server②Give

○○.△△.□□.×× to MAC:hope

Broadcast

The Internet and IP address

Principle： The Internet is formed with global IP address

Communication model of layer 4 (End-to-End)

IP address+

TCP/UDP+

Port number

IPv4 address exhaustion and IPv6

Solve IPv4 exhaustion problem fundamentally (Long Term Solution)

→ Introduction of IPv6 addressIs composed with 128bit electrical information, divide each 16bit into 8

numbers by [:]. This is 128 bit in binary number, so total address is 2128

• Kinds of IPv6 - Unicast address - Link local scope

- Anycast address - Global scope

- Multicast address

- Broadcast address

2001:0DB8:0:CD30:123:4567:89AB:CDEF /64

64bit subnet prefix 64 bit internet identifier ↑prefix length

128 bit

Private Address and NAT

RPrivate Address Translate dynamically

Communicate by global address + port

Global Address + translated port↑

Private Address + Port

Computer

• ARP (Address Resolution Protocol)

• RARP (Reverse Address Resolution Protocol)

– Protocol demanding IP address from MAC address

①Demand MAC Address from ○○.△△.□□.××

②MAC address is hoge

Broadcast

ARPIP address: ◯◯.△△.□□.××

MAC: hoge