Authentication/Authorization/Accounting

Authentication is the process of identifying who the entity is or what it claims to be. Example To log in into the computer we need user-name and password, this is authentication.
Authorization is which resources a user or an entity can access.
Accounting keeps track of all what resource have been accessed and for what interval.


Rip version2 supports authentication. It authenticates the route updates. Rip authenication can be plain or encrypted using MD5

configuration for plain text authentication

r>enable
r#conf t
r(conf)#key chain ring
r(conf-keychain)#key 1
r(conf-keychain-key)#key-string cisco
r(conf-keychain-key)#exit
r(conf)#int s0/0
r(conf-if)#ip rip authentication key-chain ring



configuration for MD5 authentication

After configuring the key chain and key string use MD5 authentication under an interface

r(conf-if)#ip rip authentication mode MD5


Eigrp supports only Md5 authentication

Configuration

r>enable
r#conf t
r(conf)#key chain ring
r(conf-keychain)#key 1
r(conf-keychain-key)#key-string cisco
r(conf-keychain-key)#exit
r(conf)#int s0/0
r(conf-if)#ip authentication eigrp 10 key-chain ring
r(conf-if)#ip authentication eigrp 10 mode Md5

Injecting Default routes

Injecting default route...
The purpose of injecting default route into an Eigrp process is to make the routers under the routing protocol to point to the router on which default route is configure.
There are different ways to do this.
1)Default-information originate:-
This command is used to inject the default route into the rip process, so as to make the routers to point towards the router on which command is set or we can say that this command enables router under the protocol (rip etc) to point towards the router on which default-information originate is set
2)Redistribution.
3)IP Summary-address.
Injecting default route using redistribution.

Scenario
3 routers A,B and C running Eigrp protocol and router A is an edge router pointing towards ISP and default route is configured on router A

Configuration.

RouterA>enable
RouterA#conf t
RouterA(config)#router eigrp 10
RouterA(config-router)#redistribute static
RouterA(config-router)#CTRL+Z
RouterA#



Configuration for Default information originate for same scenario

RouterA>enable
RouterA#conf t
RouterA(config)#router rip
RouterA(config-router)#version 2
RouterA(config-router)#default-information originate
RouterA(config-router)#CTRL+Z
RouterA#

Configuration for Summary Address



RouterA>enable
RouterA#conf t
RouterA(config)#int s0/1
RouterA(config-if)#ip summary-address eigrp 10 0.0.0.0 0.0.0.0
RouterA(config-if)#CTRL+Z
RouterA#

configuring passive interface in eigrp

Passive interface in Eigrp

Configuring passive interface in eigrp does not work like rip. However in eigrp, inorder to send unicast updates we need to add the neighbour router interface ip address under interface mode.


router1>en
router1#conf terminal
router1(conf)#interface s 0/0
router1(conf-if)#neighbor 10.0.0.2 s0/0

similar is the configuration for router2
and u will have unicast updates send across the neighbor routers.


Route summerization.

Summerization is done inorder to decrease the size of routing table...
so as to save bandwidth and to stop sending updates due to flapping of any network.


Scenario:

A router with 3 loopbacks and and serial interface...
objective:Sending of summerized route through the interface

Configuration
router>en
router#configure terminal
router(config)#int serial interface 0/0
router(config-if)#ip address 10.0.0.1 255.0.0.0
router(config-if)#no shutdown


router(config)#int loopback 0
router(config-if)#ip address 1.1.1.1 255.255.255.0
!
router(config)#int loopback 1
router(config-if)#ip address 1.1.2.1 255.255.255.0
!
router(config)#int loopback 2
router(config-if)#ip address 1.1.3.1 255.255.255.0
!
router(config)#router eigrp 10
router(config-router)#net 10.0.0.0
router(config-router)#net 1.1.1.0
router(config-router)#no auto-summary
router(config-router)#exit
router(config)#int s 0/0
router(config-if)#ip summary-address eigrp 10 1.1.1.0 255.255.252.0

Cross Cable

One End of the Cable                Second End of the Cable


White Orange                              white green
Orange                                        green
white Green                                 white orange
blue                                             blue
white blue                                    white blue
Green                                          orange
white brown                                white brown
Brown                                         brown

Routing protocols

There are two types of protocols.
1.Routed  2. Routing
Routed protocols are those protocols which are meant to carry information to the required destination like IP , IPX etc.
Routing protocols are meant for finding all possible routes in the internetwork. like Rip , Igrp, Eigrp, Bgp

Routing is the process of finding the route to reach the destination in the internetwork.
Routing can be static, dynamic and default.
Dynamic routing include routing protocols which automatically find the routes in the network.
Dynamic Routing Protocols can be either IGP or EGP.
Igp protocols are the protocols which are meant for a particular region, boundary or a single autonomous number. some of them include RIP, OSPF, EIGRP, IGRP..

BGP is the EGP protocol which is used between two different autonomous system or numbers and is meant for global networks.

Layer 2 & layer 3 devices....

Switch is normally a layer 2 device. It populates its Mac table with mac entries of the devices to which it is connected by Broadcast at first, then multicast and finally with unicast. Switches are used to provide seperate collision domain in the network.

Routers and layer 3 switches are in the category of layer 3 devices.
Nomally layer 3 devices are all those devices to which ip address can be allocated, which includes computer as well.

t1/t3

T1 and T3 are the types of leased lines
T1 is a high speed dedicated leased line for telecommunication..it provides speed up to 1.56Mpbs.

T3 is the combination of 28 t1 lines  for much higher speed ...