Routing

It is a process of enabling communication between two different networks.

There are two types of routers.
1. Hardware router
2. Software router

Hardware router is a physical hardware device.

Software router: A server with 2 NICs called software router.
Ex: NT, 2000, 2003, UNIX can be configured as software router
A computer with 2 NICs is called a multihomed system.

Requirements of the Software Router:

DC or member server or stand alone machine
2 NIC cards
Two different networks
Routing &RAS service

Benefits of Routing:

1. DUN (Dial Up Networking)
2. NAT (Network Address Transmission)
3. Basic firewall
4. VPN (Virtual Private Network)
5. LAN routing

Enabling LAN routing:

Start > P> Admin tools>RRAS>r/c server> configure & enable routing.

NAT: 

It is a service of routing provides network address translation from private to public
When we have 2 networks public & private in order to protect private network from public network (intruders) we need NAT.
NAT enables one way communication. I.e. private network can communicate with public network but not vice versa.

Implementing NAT:

S-P- Admin tools
Open RRAS
Expand IP routing
Right click on general
New- routing protocol – select NAT/basic firewall – ok

Adding interfaces
Right click on NAT/basic firewall
Select new interface
Select the private interface
Ok
Again right click on NAT basic services
New interface
Select public interface
Click on public inter face connected to the internet
Checks the box enable NAT on this interface
Apply – ok

Verification:

On private network
Go to command prompt
Ping public network
It should ping
Move on to public network
Ping private network
It should not ping

Disabling NATing
On router
Open RRAS – expand IP routing
Right click on NAT /basic firewall
Delete – yes

Routing Protocols:

1. Static
2. Dynamic

Dynamic:

It requires dynamic routing protocols there are a few dynamic routing protocols. Dynamic routing enables a router could prepare dynamically automatically on its own.
i.e., when a router is added or removed when there is a change of I.P.S. etc. will be known by the dynamic routing protocols, to see the routing table.
On command prompt
Type root print

Routing table contains the information about

Network destination: destination of the packet reached
Net mask: subnet mask of the system.
Gateway: another router’s address
Interface: Local NIC’s address
Metric: determines best path

RIP (Routing Information Protocol)
OSPF (Open Shortest Path first)
NAT
IGMP (International group management)
IGRP (international gateway)
DHCP Relay agent

Static routing:

It does not require any protocols; an administrator has to create a routing table which is constant or not changeable.