It
forwards packets from one network to another network. It choose the best path
from the routing table. The best path selection is based on the type of routing
we are using (static/dynamic).
Types of Routing:
-
Static Routing
-
Default Routing
-
Dynamic Routing
Static Routing:
-
Best path is configured manually by the Administrator
-
Administrator should know / Mandatory need of Destination Network ID
-
It is secure and fast
Disadvantages:
-
Everything should be configured manually
-
It is used only in small network
-
Any (small) changes will effect complete network
Default Routing:
-
It is used to route traffic for unknown destinations (eg., internet)
-
It is also used at end locations
-
It is the last preferred routing
-
Default routes helps in reducing the size of routing table
Dynamic
Routing:
Advantages of
Dynamic over Static:
-
No need of manual configuration (unlike static routing)
-
Learns about other networks via advertisements (of directly connected networks)
-
Automatically select the best route (builds routing table)
-
Update the topology changes dynamically
-
No need to know the destination networks
-
Administrative work is reduced
-
Applicable for large organizations
Types of Dynamic Routing Protocols,
-
Distance Vector Protocol
-
Link State Protocol
-
Hybrid Protocol
Differences of Dynamic routing protocols,
Classfull
Protocols:
-
Classfull routing protocol do not carry the subnet mask information along with
updates
-
All devices in the network must use the same subnet mask (FLSM or default same
class)
Classless
Protocols:
-
Classless routing protocol carry the subnet mask information along with updates
-
That is why it supports sub networks (VLSM and FLSM) and even default network
as well
Routing
Information Protocol:
-
Open standard protocol (Cisco / Non-Cisco)
-
Classfull routing protocol (does not carry subnet mask)
-
Any Updates which will broadcasted via 255.255.255.255
-
Metric: Hop count
-
Load Balancing up to 4 equal paths
-
Max Hop counts = 15 / Max routers = 16
-
Applicable for small organizations
-
Administrative distance is 120
-
Exchange entire routing table for every 30 seconds (periodic updates)
Routing
Protocol Classification:
IGP:
-
Interior Gateway Protocol
-
It is used to communicate within same autonomous system
-
RIP, IGRP, EIGRP, OSPF, IS-IS
EGP:
-
Exterior Gateway Protocol
-
It is used to communicate between two or more autonomous system
-
Border Gateway Protocol
Administrative
Distance:
- Trust worthiness
of the information received by the router
- The number is
between 0 and 255
- Less AD value is
more preferred routing
Autonomous System
Number:
- It is a collection
of networks under a common administrative domain
- A unique number
identifying the routing domain of the routers (one organization)
- Ranges from 1 –
65535
Private Autonomous
System:
- Used with in the
same service provider
- Unique with in
service provider
- Range between
64513 – 65535
Public Autonomous
System:
- Used between
multiple service provider
- Globally unique
- Range between 1 –
64512
“All credits
regarding networking topics goes to NOA Solutions. If any one is
interested recommending to start with NOA solutions.”