Intro. to Networks

This lecture will consist• Internet and Ethernet short history• Layer model (ISO and IP)• Routing and routers• Linux routing table• PPP short history and purpose• PPP and Linux

Internet & Ethernet Brief history

Internet (http://www.isoc.org/internet/history/)

• 1969 – ARPANET (The Internet origin)

• 1969 – UNIX

• 1972 – Ethernet

• 1989 – WWW

• 1991 – Linux

• 1992 –Mosaic

Internet organization

• ISOC – http://www.isoc.org

• IETF – http://www.ietf.org

• IETF RFCs – http://www.ietf.org/rfc

• IANA – http://www.iana.org

• IAB – http://www.iab.org

• W3C – http://www.w3c.org

Other org. involve in Networks

• ISO – http://www.iso.ch

• ITU – http://www.itu.int

• IEEE – http://www.ieee.org

OSI layers via Internet layers

OSI

• Physical• Data link• Network• Transport• Session• Presentation• Application

IP

• Ethernet hardware• Ethernet• IP stack• TCP/UDP stack

• IP applications

LAN MAC Addresses

• Registration through the IEEE.

• XX-XX-XX-XX-XX-XX

• Vendor register leading XX-XX-XX.

• Example: 3Com register 00-05-1A

• Example: a NIC made by 3Com

• 00-05-1A-0C-01-93

Making LAN

We need 4 component to make LAN

• Cables

• NICs in the PCs or other (e.g. Printers)

• Hubs (Repeaters)

• Switches

Configure NIC

• Use hotplug.

• lspci , lspci -n

• PCI Vendor ID. (on the Internet)

• /lib/modules/<kid>/kernel/drivers/net/

• USB Cable, USB ADSL => USB NIC.

• lsmod

• ifconfig -a

IP v4 Address

• Class A 1.0.0.0-126.0.0.0 7/24

• Class B 128.1.0.0-191.254.0.0 14/16

• Class C 192.0.1.0-223.255.254.0 22/8

• Class D 224.0.0.0-239.255.255.255

• Class E 240.0.0.0-254.255.255.255

IP Network and subnets

• A name for IP based LAN.

• IP Network – mask according to class.

• IP sub network have a smaller mask.

• Example:

• 10.1.0.0, 255.255.0.0 is subnet class A.

Address Resolution Protocol

• RFC 826

• Map LAN MAC into the IP address.

• Dynamic ARP.

• Manual ARP

• Static ARP.

Linux LAN

• ifconfig -a – See your interfaces

• arp -n – See the ARP table

• arp -s ip mac – Set ARP

• route -n

• ip - iproute2 tool

IP routing.

RouterServer

00-05-1B-1A-3C-B4

10.1.14.12410.1.14.110.101.15.110.101.15.73

00-02-B3-1D-5E-87

00-02-BA-13-BC-11

00-02-BA-13-BC-13

Dst 10.101.15.73Src 10.1.14.124Dst MAC 00-02-BA-13-BC-11Src MAC 00-05-1B-1A-3C-B4

IP routing.

RouterServer

00-05-1B-1A-3C-B4

10.1.14.12410.1.14.110.101.15.110.101.15.73

00-02-B3-1D-5E-87

00-02-BA-13-BC-11

00-02-BA-13-BC-13

Dst 10.101.15.73Src 10.1.14.124Dst MAC 00-02-B3-1D-5E-87Src MAC 00-02-BA-13-BC-13

Routing table

• Default Gateway.• Simple example:• Destination Gateway Genmask Flags Metric Ref Use Iface

• 10.1.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

• 0.0.0.0 10.1.0.1 0.0.0.0 UG 0 0 0 eth0

A real route

• RIP – RFC 1058, 1388, 1723

• OSPF - RFC 2178 (v2)

• BGP - RFC 1771 (BGP-4)

• PIM – RFC 2362, 3973

• OSI IS-IS

• IGRP, EIGRP – Cisco.

• Real routers are not just routers!

PPP

• Point to Point Protocol

• IP protocol for connecting PC over phone line.

• Use tty char device for transferring IP packets.

• RFC 1661, RFC 1662 (STD 51)

• HDLC ISO 3309

Why PPP?

• Phone lines.

• Authentication.

• Bandwidth and QoS control

• Dynamic client to ISP mapping.

• Easy configuration VPN.

• Compression option.

• Packets concatenating.

PPP structure

• LCP – Create the PPP link.

• PAP or CHAP authentication.

• HDLC – Octet/Bit stuffed framing

PPP over link layer

• PPPoE - RFC 2516

• PPPoA – RFC 2364

• MAC address or VP instead of phone line.

PPP over IP

• L2TP – RFC 2661, RFC 3931 (v3)

• PPTP – RFC 2637

• Server IP instead of phone number.

• Two IP networks with one IP stack

• Need a more complicated routing.

• Possible to work L2TP over PPPoE.

PPP over IP routing

• Simple example:• Destination Gateway Genmask Flags Metric Ref Use Iface

• 132.64.140.2 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0

• 10.1.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

• 0.0.0.0 132.64.140.2 0.0.0.0 UG 0 0 0 ppp0

Linux PPP tools

• The PPP daemon

• PPTP client – works with the pppd.

• L2TP – status unknown.

• PPPoE

• PPPoA – kernel patch with ATM driver.

• Kernel 2.6 - PPP, PPPoE, PPPoA