实验28:HDLC PPP 封装
1. 实验目的
通过本实验,读者可以掌握如下技能:
1) 串行链路上的封装概念
2 HDLC 封装
3 PPP 封装
2. 实验拓扑
如图:
 
3. 实验步骤
注:
显示串行接口时,常见以下几种状态:
Serial0/0/0 is up, line protocol is up
//链路正常
Serial0/0/0 is administratively down, line protocol is down
//没有打开该接口,执行“no shutdown”可以打开接口
Serial0/0/0 is up, line protocol is down
//物理层正常,数据链路层有问题,通常是没有配置时钟、两端封装不匹配、PPP 认证错误
Serial0/0/0 is down, line protocol is down
//物理层故障,通常是连线问题
配置如下:
r0(config)#int s0/0
r0(config-if)#ip add 172.16.1.1 255.255.255.0
r0(config-if)#no sh
r0(config-if)#
*Mar  1 00:01:31.655: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up
*Mar  1 00:01:32.659: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
*Mar  1 00:01:57.271: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
r0(config-if)#
r0(config-if)#do sh ip int s0/0
Serial0/0 is up, line protocol is down
  Internet address is 172.16.1.1/24
  Broadcast address is 255.255.255.255
  Address determined by setup command
  MTU is 1500 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are always sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is enabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF Fast switching turbo vector
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled
r0(config-if)#
*Mar  1 00:03:17.263: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r0(config-if)#do sh int s0/0
Serial0/0 is up, line protocol is up
  Hardware is GT96K Serial
  Internet address is 172.16.1.1/24
  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, loopback not set//该接口的默认封装为HDLC 封装
  Keepalive set (10 sec)
  CRC checking enabled
  Last input 00:00:01, output 00:00:02, output hang never
  Last clearing of "show interface" counters 00:02:53
  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
     7 packets input, 764 bytes, 0 no buffer
     Received 7 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     20 packets output, 1960 bytes, 0 underruns
     0 output errors, 0 collisions, 5 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up
         
r0(config-if)#
r0(config-if)#
r0(config-if)#
r0(config-if)#enc 
r0(config-if)#encapsulation ppp
r0(config-if)#
*Mar  1 00:04:33.727: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
r0(config-if)#
r0(config-if)#do ping 172.16.1.2
 
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
由于R1还没有封装PPP,链路两端封装不同协议所以PING不通
 
r0(config-if)#
*Mar  1 00:05:39.947: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r0(config-if)#do ping 172.16.1.2
 
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/21/64 ms
链路的两端封装相同,则ping 测试应该正常
 
r0(config-if)#
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/21/64 ms
r0(config-if)#do sh int s0/0
Serial0/0 is up, line protocol is up
  Hardware is GT96K Serial
  Internet address is 172.16.1.1/24
  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation PPP, LCP Open//该接口的封装为PPP 封装
 
  Open: IPCP, CDPCP, loopback not set//网络层支持IP CDP 协议
 
  Keepalive set (10 sec)
  CRC checking enabled
  Last input 00:00:43, output 00:00:02, output hang never
  Last clearing of "show interface" counters 00:03:55
  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
     58 packets input, 2928 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
     69 packets output, 3012 bytes, 0 underruns
         
r0(config-if)#
 
 
 
 
 
r1(config)#int s0/0
r1(config-if)#ip add 172.16.1.2 255.255.255.0
r1(config-if)#no sh
r1(config-if)#do sh
*Mar  1 00:03:00.043: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up
r1(config-if)#do sh ip int
*Mar  1 00:03:01.047: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r1(config-if)#do sh ip int s0/0
Serial0/0 is up, line protocol is up
  Internet address is 172.16.1.2/24
  Broadcast address is 255.255.255.255
  Address determined by setup command
  MTU is 1500 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are always sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is enabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF Fast switching turbo vector
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled
r1(config-if)#
r1(config-if)#
r1(config-if)#
*Mar  1 00:04:57.355: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
r1(config-if)#do sh int s0/0
Serial0/0 is up, line protocol is down
  Hardware is GT96K Serial
  Internet address is 172.16.1.2/24
  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 00:00:29, output 00:00:00, output hang never
  Last clearing of "show interface" counters 00:04:13
  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
     35 packets input, 2518 bytes, 0 no buffer
     Received 35 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     18 packets output, 1316 bytes, 0 underruns
     0 output errors, 0 collisions, 3 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up
         
r1(config-if)#
r1(config-if)#
r1(config-if)#
r1(config-if)#en
r1(config-if)#encapsulation ppp
r1(config-if)#
*Mar  1 00:05:41.015: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r1(config-if)#