Static Routing and Default Routing

Routing

Forwarding of packets from one network to another network choosing the best path from the routing table. Routing table consists of only the best routes for every destination.

Types of Routing
1. Static Routing
2. Default Routing
3. Dynamic Routing

Static Routing

• It is configured by Administrator manually.
• Mandatory need of Destination Network ID
• It is Secure & fast
• Used for Small organizations with a network of 10-15 Routers.
• Administrative distance for Static Route is 0 and 1.

Disadvantages:-
• Used for the small network.
• Everything to manually
• Network change effect complete N/W

Configuring Static Route
Router(config)# ip route <Destination Network ID> <Destination Subnet Mask> <Next-hop IP address >
Or
Router(config)# ip route <Destination Network ID> <Destination Subnet Mask> <Exit interface type><interface number>

 Default Routing

• Manually adding the single route for the entire destination. Default route is used when the destination is unknown
• Last preferred route in the routing table
• When there is no entry for the destination network in a routing table, the router will
forward the packet to its default router.
• Default routes help in reducing the size of your routing table.
Configuring Default Route
 
Router(config)# ip route <Destination Network ID> <Destination Subnet Mask>
<Next-hop IP address >

Or

Router(config)# ip route <Destination Network ID> <Destination Subnet Mask>
<Exit interface type><interface number> 

DYNAMIC ROUTING

Advantages of Dynamic over static:

• There is no need to know the destination networks.
• Need to advertise the directly connected networks.
• Updates the topology changes dynamically.
• Administrative work is reduced
• Used for large organizations.
• Neighbor routers exchange routing information and build the routing table
automatically.

Types of Dynamic Routing Protocols

• Distance Vector Protocol
• Link State Protocol
• Hybrid Protocol 

Administrative Distance
 
• Rating of the Trustworthiness of a routing information source.
• The Number is between 0 and 255
• The higher the value, the lower the trust.

Default administrative distances are as follows :

• Directly Connected = 0
• Static Route = 1
• IGRP = 100
• OSPF = 110
• RIP = 120
• EIGRP = 90/170