Configuración de Enlaces Point-to-Point usando PPP o HDLC

By delfirosales 16:01 Cisco Router, Layer 2, PPP, WAN

HDLC (High-Level Data Link Control, control de enlace síncrono de datos) es un protocolo de comunicaciones de propósito general punto a punto y multipunto, que opera a nivel de enlace de datos. Se basa en ISO 3309 e ISO 4335. Surge como una evolución del anterior SDLC. Proporciona recuperación de errores en caso de pérdida de paquetes de datos, fallos de secuencia y otros, por lo que ofrece una comunicación confiable entre el transmisor y el receptor. De este protocolo derivan otros como LAPB, LAPF, LLC y PPP.

Configuración de HDLC

R1#configure terminal
R1(config)#interface Serial0/0
R1(config-if)#encapsulation hdlc
R1(config-if)#ip address 192.168.12.1 255.255.255.252
R1(config-if)#no shutdown

R2#configure terminal
R2(config)#interface Serial0/0
R2(config-if)#encapsulation hdlc
R2(config-if)#ip address 192.168.12.2 255.255.255.252
R2(config-if)#no shutdown

R1#show interface Serial0/0
Serial0/0 is up, line protocol is up
Hardware is GT96K Serial
Internet address is 192.168.12.1/30
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
CRC checking enabled
Last input 00:00:01, output 00:00:00, output hang never
Last clearing of "show interface" counters 00:34:44
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
     Conversations 0/1/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
     239 packets input, 16566 bytes, 0 no buffer
     Received 234 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     249 packets output, 17471 bytes, 0 underruns
     0 output errors, 0 collisions, 4 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up DSR=up DTR=up RTS=up CTS=up

R2#ping 192.168.12.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.12.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/35/72 ms

Point-to-Point Protocol

Point-to-point Protocol (Protocolo punto a punto), también conocido por su acrónimo PPP, es un protocolo de nivel de enlace estandarizado en el documento RFC 1661. Por tanto, se trata de un protocolo asociado a la pila TCP/IP de uso en Internet.

R1#configure terminal
R1(config)#interface Serial0/0
R1(config-if)#encapsulation ppp
R1(config-if)#ip address 192.168.12.1 255.255.255.252
R1(config-if)#no shutdown
R1(config-if)#

R2#configure terminal
R2(config)#interface Serial0/0
R2(config-if)#encapsulation ppp
R2(config-if)#ip address 192.168.12.2 255.255.255.252
R2(config-if)#no shutdown
R2(config-if)#

R2#show interface Serial0/0
Serial0/0 is up, line protocol is up
Hardware is GT96K Serial
Internet address is 192.168.12.2/30
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, LCP Open
Open: IPCP, CDPCP, loopback not set
Keepalive set (10 sec)
CRC checking enabled
Last input 00:00:16, output 00:00:08, output hang never
Last clearing of "show interface" counters 00:06:03
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
     Conversations 0/1/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
     83 packets input, 3580 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     83 packets output, 3580 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up DSR=up DTR=up RTS=up CTS=up

R2#ping 192.168.12.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.12.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/46/68 ms

Comandos debug de PPP

debug ppp authentication
debug ppp negotiation
debug ppp packet
debug ppp error
debug ppp chap

Cisco Router, Layer 2, PPP, WAN