Download Intro. to Networks

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.
Server
10.101.15.73
Router
10.101.15.1
10.1.14.1
10.1.14.124
00-02-BA-13-BC-11
00-02-BA-13-BC-13
00-02-B3-1D-5E-87
00-05-1B-1A-3C-B4
Dst 10.101.15.73
Src 10.1.14.124
Dst MAC 00-02-BA-13-BC-11
Src MAC 00-05-1B-1A-3C-B4
IP routing.
Server
Router
10.101.15.1
10.101.15.73
10.1.14.1
10.1.14.124
00-02-BA-13-BC-11
00-02-BA-13-BC-13
00-02-B3-1D-5E-87
Dst 10.101.15.73
Src 10.1.14.124
Dst MAC 00-02-B3-1D-5E-87
Src MAC 00-02-BA-13-BC-13
00-05-1B-1A-3C-B4
Routing table
• Default Gateway.
• Simple example:
•
Destination Gateway Genmask
•
10.1.0.0
0.0.0.0
•
0.0.0.0
10.1.0.1 0.0.0.0
Flags Metric Ref Use Iface
255.255.0.0 U
0
0
0
eth0
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
•
132.64.140.2 0.0.0.0
255.255.255.255 UH 0
0
0
ppp0
•
10.1.0.0
255.255.0.0
0
0
0
eth0
•
0.0.0.0
UG 0
0
0
ppp0
0.0.0.0
132.64.140.2 0.0.0.0
Flags Metric Ref Use Iface
U
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