PPP

PPP Architecture

PPP allows other protocols to run over PPP, this is an advantage over SLIP.

OSI Layer
3 Upper-layer protocols (IP, IPX, AppleTalk)
2
Network Control Protocol (NCP)
Link Control Protocol (LCP)
High-level Data Link Control (HDLC)


1 Physical Layer
(such as EIA/TIA-232, v.24, V.35, ISDN)


On your callback you can setup your access server at the central site, so the modem can authenticate, then hang-up and call you back. This allows for a little more security, but more to save long-distance toll charges. “The Call Back Feature”

Multiplexing
When a router sets up, monitors and tears down multiple layer 3 protocols over a single data line.

Asynchronous PPP and Async Interface Commands
Router(config-if)#encapsulation {ppp | slip}
Router(config-if)#async mode dedicated
Router(config-if)#async mode interactive

Asynchronous Interface Commands for Addressing
Router(config-if)#peer default ip address {address | pool pool-name | dhcp}
Router(config-if)#async dynamic address
Router(config-if)#ip unnumbered {type} {number}

Asynchronous Callback Global Commands
Router(config)#username username password {password} callback-dialstring {phone-number} callback-line {line-number} callback-rotary {rotary-group-number}

Asynchronous Callback Line / Interface Commands

Router(config-if)#ppp callback accept
Router(config-if)#ppp callback initiate
Router(config)#line {line-number}
Router(config-line)#callback forced-wait {seconds}
Router(config-line)#script callback {script-name}

Configuring a PPP Callback Server
To do this, you have two routers (DTE) server/client.

Router(config)#interface s0/2
Router(config-if)#ip address 10.0.1.7 255.255.255.0
Router(config-if)#encapsulation ppp
Router(config-if)#dialer callback-secure
Router(config-if)#dialer map ip 10.0.1.8 255.255.255.0
Router(config-if)#dialer-group1
Router(config-if)#ppp callback accept
Router(config-if)#authentication chap
Router(config-if)#exit
Router(config)#map-class dialer dial1
Router(config-map-class)#dialer callback-server {username}
Router(config-map-class)#dialer hold-queue timeout 60

Configuring a PPP Callback Client

RouterClient(config)#interface s0/0
RouterClient(config-if)#ip address 10.0.1.8 255.255.255.0
RouterClient(config-if)#encapsulation ppp
RouterClient(config-if)#dialer map ip 10.0.1.7 name {server router name} {phone number}
RouterClient(config-if)#dialer-group 1
RouterClient(config-if)#ppp callback request
RouterClient(config-if)#ppp authentication chap

11:28 am

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