How to Establish Point-to-Point Connection

							How to Establish
Point-to-Point
Connection ?
 DTE and DCE devices
 DTE (Data Terminal Equipment ):These are

  devices which can create, send and receive the
  data such as router,pc etc.
 DCE (Data Communication Equipment ):
  These are the devices which always generate
  pulses or clocks etc. such as modem,
  CSU/DSU , Switch etc.
 CSU: Channel Service Unit

 DSU: Data Service Unit
SERIAL CABLES
                 S0/0                       S0/0
                 20.0.0.1/30                20.0.0.2/30
                DTE                                DTE
   F0/0         DCE                                        F0/0
   10.0.0.1/8                                              30.0.0.1/30




                   C = Connected Interface
                   Router#sh controllers s0/0
                   DCE, V.35, No Clock                     PC-2
  PC-1
  10.0.0.2/8                                               30.0.0.2/8
  10.0.0.1 DG                                              30.0.0.1 DG
Router#sh ip route                              Router#sh ip route
C:10.0.0.0/8 - f0/0                             C:20.0.0.0/30 - s0/0
C:20.0.0.0/30 - s0/0                            C:30.0.0.0/8 - f0/0
   Configuration
1.configure both router serial interfaces with same
  network IP address. (/30)
Router(config)# interface s0/0
Router(config-if)# ip address 20.0.0.1 255.255.255.252
Router(config-if)#no shutdown
2.convert one DTE interface into DCE interface
Router(config)# interface s0/0
Router(config-if)# Clock rate 64000
3.Configure WAN Encapsulation protocol at all Serial
  interfaces
Router(config)# interface s0/0
Router(config-if)# Encapsulation <protocol>
                 HDLC (High-level Data Link Control)
1.It is a proprietary protocol.
2.It support same vendors .
3.It is the default encapsulation used by Cisco routers over
   synchronous serial links.
4.It support only Synchronous Serial links (Point-to-point)
5.It is non-authenticated Protocol.

                                       CISCO HDLC


 Flag Address Control Proprietary Data FCS Flag
 • Each vendor’s HDLC has a proprietary data field to support multiprotocol environments.

                                                    HDLC

 Flag Address Control Data FCS Flag
                         • Supports only single-protocol environments.
   PPP (Point-To-Point Protocol)
1.It is an open standard protocol that support different
   vendors.
2.It is not a default Encapsulation
3.It support Synchronous /asynchronous

4.It is an Authenticated protocol.
5.It uses Link Control Protocol (LCP) to build and
   maintain data-link connections.
6.Network Control Protocol (NCP) is used to allow
   multiple Network layer protocols (routed protocols)
   to be used on a point-to-point connection.
          PPP AUTHENTICATIONS
There are two methods of authentication that can be used with PPP
  links:
PAP:-   Password Authentication Protocol
It is the less secure of the two methods. Passwords are sent in clear
    text, and PAP is only performed upon the initial link
    establishment. When the PPP link is first established, the remote
    node sends the username and password back to the originating
    router until authentication is acknowledged.
CHAP:-     Challenge Handshake Authentication Protocol
It is used at the initial startup of a link and at periodic
   checkups on
the link to make sure the router is still communicating
   with the same host.
           Configuration

Router(config)# interface s0/0
Router(config-if)# encapsulation ppp
Router(config-if)# ppp
 authentication chap