Intro' to Networks

1
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

2
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

3
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

4
Other org. involve in Networks

• ISO http//www.iso.ch
• ITU http//www.itu.int
• IEEE http//www.ieee.org

5
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

6
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

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Making LAN

• We need 4 component to make LAN
• Cables
• NICs in the PCs or other (e.g. Printers)
• Hubs (Repeaters)
• Switches

8
Configure NIC

• Use hotplug.
• lspci , lspci -n
• PCI Vendor ID. (on the Internet)
• /lib/modules/ltkidgt/kernel/drivers/net/
• USB Cable, USB ADSL gt USB NIC.
• lsmod
• ifconfig -a

9
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

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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.

11
Address Resolution Protocol

• RFC 826
• Map LAN MAC into the IP address.
• Dynamic ARP.
• Manual ARP
• Static ARP.

12
Linux LAN

• ifconfig -a See your interfaces
• arp -n See the ARP table
• arp -s ip mac Set ARP
• route -n
• ip - iproute2 tool

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IP routing.
Router
Server
10.1.14.1
10.101.15.1
10.1.14.124
10.101.15.73
00-02-BA-13-BC-11
00-02-BA-13-BC-13
00-05-1B-1A-3C-B4
00-02-B3-1D-5E-87
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IP routing.
Router
Server
10.1.14.1
10.101.15.1
10.1.14.124
10.101.15.73
00-02-BA-13-BC-11
00-02-BA-13-BC-13
00-05-1B-1A-3C-B4
00-02-B3-1D-5E-87
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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

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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!

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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

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Why PPP?

• Phone lines.
• Authentication.
• Bandwidth and QoS control
• Dynamic client to ISP mapping.
• Easy configuration VPN.
• Compression option.
• Packets concatenating.

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PPP structure

• LCP Create the PPP link.
• PAP or CHAP authentication.
• HDLC Octet/Bit stuffed framing

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PPP over link layer

• PPPoE - RFC 2516
• PPPoA RFC 2364
• MAC address or VP instead of phone line.

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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.

22
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

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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