Routing:
Routing is used for taking a packet from
one device and sending it through the network to another device on a
different network. If your network has no routers, then you are not
routing. Routers route traffic to all the networks in your internetwork.
To be able to route packets, a router must know ,at a minimum, the
following:
-Destination address
-Neighbor routers from which it can learn about remote networks
-Possible routers to all remote networks
-The best route to each remote network
-How to maintain and verify routing information
Ip Routing in Our Network
The network in the previous section has
now been configured correctly with IP addressing. there are a few
different ways to configure the routing tables to include all the
networks in our little internetwork so that packets will be forwarded.
However, the best way for one network is not necessarily best for
another. if you understand the different routing types, you will be able
to decide what fits best in your business requirements. The different
types of routing you will learn about in this chapter include the
following:
-Static routing
-Default routing
-Dynamic routing
We will start off by describing and
implementing static routing on our network. Why? Because if you can
implement static routing and make it work, it means you have a good
understanding of the internetwork.
[Note:- we are going to give all kind of routing example of this session with following configuration]
Ip routing example with more routers
Network Addressing for the IP Network
| Router Network Address Interface Address |
| 2621 A
172.16.10.0
f0/0
172.16.30.11841A 172.16.10.0
e0
172.16.30.21841A 172.16.20.0
s0/0/0
172.16.30.11841B
172.16.20.0 s0/0/0
172.16.30.2
1841B 172.16.40.0
s0/0/1
172.16.30.1 1841B 172.16.30.0 e0 172.16.30.1 1841C 172.16.40.0 s0/0/0 172.16.30.2 1841C 172.16.50.0 e0 172.16.30.1 |
Static routing is the process of an administrator manually adding routers in each router’s routing table.
There are benefits and disadvantages to all routing processes. Static routing has the following benefits:
-No overhead on the router CPU
-No bandwidth usages between routers
-Security ( because the administrator only allows routing to certain networks)
Static routing has the following disadvantages:
-The administrator must really understand the internetwork and how each router is connected to
-If one network is added to the internetwork n,the administrator must add a route to it on all routers.
-It’s not fessible in large networks because it would be a full –time job.The command used to
add a static route to a routing table is:-
ip route [destination_network] [mask] [next_hop_address or exitinterface] [administrative_distance] [permanent]
The following list describes each command in the string:
ip route The command used to create the static route.
destination network The network you are placing in the routing table.
mask Indicate s the subnet mask being used on the network.
next hop address The address of
the next hop router that will receive the packet and forward it to the
remote network. This is a router interface that is on a directly
connected network .You must be able to ping the router interface before
you add the route.
exit interface Used in place
of the next hop address if desired. Must be on a point –to point link,
such as a WAN. This command does not work on a LAN; for example,
Ethernet.
administrative distance By
default, static routers have an administrative distance if 1.You can
change the default value by adding an administrative weight at the end
of the command.
permanent if the interface is
shut down or the router cannot communicate to the next hop router, the
route is automatically discarded from the routing table. Choosing the
permanent option keeps the entry in the routing table no matter what
happens.
Example:-
2621A (config)#ip route 172.16.20.0 255.255.255.0 172.16.10.2
2621A (config)#ip route 172.16.30.0 255.255.255.0 172.16.10.2
2621A (config)#ip route 172.16.40.0 255.255.255.0 172.16.10.2
2621A (config)#ip route 172.16.50.0 255.255.255.0 172.16.10.2
Display with :
2621A#Show ip route static
2621A #sh ip route
CVodes :C -connected ,S -static,I
-IGRP,R -RIP,M –[output cut]Gateway of last resort is not set
172.16.0.0/24 is subnetted,5 subnets
S 172.16.50.0 [1/0]via 172.16.10.2
S 172.16.40.0 [1/0]via 172.16.10.2
S 172.16.30.0 [1/0]via 172.16.10.2
S 172.16.20.0 [1/0]via 172.16.10.2
S 172.16.10.0 [1/0]via 172.16.10.2
C 172.16.10.0 is directly connected. Fast Ethernet 0/0
0 comments:
Post a Comment