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
Dec 28, 2015
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