1. Basic TCP/IP Networking
WeeSan Lee

2. Roadmap The Internet How the Internet is managed? TCP/IP IP Addresses
CIDR
IPv6
IP Address Allocation
NAT
Hostname and IP Address Assignment
Routing vs Forwarding

3. The Internet Inter-networks via TCP/IP Originated from ARPANET
Established in 1969 by DARPA
Not invented by Al Gore!!!
ARPANET → NSFnet
NSFnet was commercialized in 1994
With help from Routing Arbiter Project
Now, the Internet is a collection of networks managed by ISPs, who exchange traffic at NAPs

4. How the Internet is managed?
ISPs manage their own networks
Several organizations involve
ICANN
The Internet Corporation for Assigned Names and Numbers
IETF
The Engineering Task Force
RFC-Editor
Request For Comments
RFC2555, 30 Years of RFCs

5. TCP/IP HTTP FTP SSH SMTP DNS Application layer TCP UDP Transport layer
ICMP IP
IGMP
Network layer
ARP/RARP
Hardware Interface
Link layer

6. TCP/IP (cont)
"Be liberal in what you accept, and conservative in what you send." – Jon Postel ( )

7. TCP/IP (cont)
HTTP
HTTP
TCP
TCP
The Internet IP IP
Ethernet
Ethernet

8. IP Addresses IPv4 Historical Internet address classes
4 bytes, eg
Network & Host portion
Historical Internet address classes
A N.H.H.H
B N.N.H.H
C N.N.N.H D E

9. IP Addresses (cont) Problems Solutions
Class B addresses were running out by 1995
Routing tables were too big to fit into memory
Fragmentation
Solutions
Short-term
CIDR – Classless Inter-Domain Routing
Long-term
IPv6

10. CIDR No more classes Uses prefix, /00 notation, eg.
/16
Can be difficult to compute, eg. /26
Uses

11. IPv6 16 bytes Consume more memory on routers?
128 bits
Consume more memory on routers?
Ready for years but too costly to deploy

12. IP Address Allocation
ICANN delegates blocks of addresses to 5 regional Internet registries
ARIN
APNIC
RIPE
AfriNIC
LACNIC

13. NAT Network Address Translation
Translation private IP addresses into public
Private IP addresses (RFC1918)
A /8
B /12
C /16
It’s a hack but it works
Some researchers hate it since it breaks e2e

14. Hostname and IP Address Assignment
/etc/hosts
localhost
eon.cs.ucr.edu eon
DNS
Domain Name System
DHCP
Dynamic Host Configuration Protocol

15. Hostname and IP Address Assignment (cont)
/bin/hostname
Set or display current hostname
/bin/ifconfig
Enable and disable a network interface
$ ifconfig eth0 up
$ ifconfig eth0 down
Set IP address, subnet mask, broadcast address
$ ifconfig eth netmask
$ ifconfig eth0
$ ifconfig -a

16. Routing vs Forwarding Routing Forwarding Routing table
A process to build up a routing table
Forwarding
A process to forward packets from one NIC to another by consulting the routing table
Routing table
$ netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
U eth0
U eth0
UG eth0

17. Reference
LAH
Ch 12: TCP/IP Networking