PPP配置相关（学习笔记） 推荐

PAP认证配置

拓扑：A、B两个路由器s1/0相连，B为主认证端，A为被认证端

B

B(config)#username cainiao password 0 1234
B(config)#int s1/0
B(config-if)#clock rate 64000
B(config-if)#encapsulation ppp
B(config-if)#ip addr 192.168.0.10 255.255.255.0
B(config-if)#shut
B(config-if)#no shut
B(config-if)#
00:03:22: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
B(config-if)#ppp authentication pap
B(config-if)#
00:05:09: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
00:05:10: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up

A

A(config)#int s1/0
A(config-if)#encapsulation ppp
A(config-if)#ip addr 192.168.0.100 255.255.255.0
A(config-if)#shut
A(config-if)#no shut
A(config-if)#
00:04:27: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
A(config-if)#ppp pap sent-username cainiao password 0 1234
A(config-if)#
00:05:07: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up
A(config-if)#end
A#
00:05:16: %SYS-5-CONFIG_I: Configured from console by console
A#ping 192.168.0.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.10, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/68/72 ms
A#

CHAP认证配置

拓扑：A、B两个路由器s1/0相连，B为主认证端，A为被认证端

B

Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname B
B(config)#line console 0
B(config-line)#exec-timeout 0 0
B(config-line)#logging synchronous
B(config-line)#exit
B(config)#no ip domain-lookup
B(config)#int s1/0
B(config-if)#encapsulation ppp
B(config-if)#clock rate 64000
B(config-if)#ip addr 192.168.0.20 255.255.255.0
B(config-if)#shut
B(config-if)#no shut
B(config-if)#
00:04:08: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
B(config-if)#
00:04:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up
B(config-if)#exit
B(config)#exit
B#pin
00:04:23: %SYS-5-CONFIG_I: Configured from console by console
B#ping 192.168.0.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.10, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/63/72 ms
B#conf t
Enter configuration commands, one per line. End with CNTL/Z.
B(config)#username cainiao password 0 1234
B(config)#int s1/0
B(config-if)#ppp authentication chap
B(config-if)#
00:06:25: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down
B(config-if)#
00:07:03: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up
B(config-if)#

A

Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname A
A(config)#line console 0
A(config-line)#exec-timeout 0 0
A(config-line)#logging synchronous
A(config-line)#exit
A(config)#no ip domain-lookup
A(config)#int s1/0
A(config-if)#encapsulation ppp
A(config-if)#ip addr 192.168.0.10 255.255.255.0
A(config-if)#shut
A(config-if)#no shut
A(config-if)#
00:02:16: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
A(config-if)#
00:04:03: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up
A(config-if)#
00:06:18: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down
A(config-if)#
00:06:19: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
A(config-if)#ppp chap password 0 1234
A(config-if)#ppp chap hostname cainiao
A(config-if)#
00:06:56: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up
A(config-if)#
00:06:57: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up
A(config-if)#exit
A(config)#exit
A#pin
00:07:15: %SYS-5-CONFIG_I: Configured from console by console
A#ping 192.168.0.20
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.20, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/44/72 ms

IP地址协商配置

PPP支持IP地址协商，当用户拨号上网时，通常由路由器为客户端分配一个动态IP地址。

router(config-if)#peer default ip address 192.168.0.100 //服务器端配置，分配给对端的IP地址

router(config-if)#ip address negotiated //客户端配置，本端IP地址由对端分配

在客户端配置此命令后，原先在接口上配置的IP地址将会被删除。当PPP连接建立后，将会由服务器端分配一个IP地址；如果PPP连接被断开，分配到的IP地址将会被删除，接口又会回到没有IP地址状态。
如果在服务器端配置了为对端分配IP地址，而在客户端又没有使用命令ip address negotiated，将会导致PPP连接不能正常工作。

PPP压缩配置

在配置PPP压缩的时候需要注意，PPP压缩必须在链路的两端均配置后才能生效。如果只在PPP链路的一端配置了压缩而另一端没有配置压缩，则PPP压缩将不会生效。

PPP的压缩有很多种，其中2种：

链路压缩配置

router(config-if)#compress {predictor | stac}

predictor：该算法学习数据串，它尝试从一个操作检索系统中来预测出即将到来的特征数据序列。predictor算法对路由器的RAM要求很高，如果路由器没有配备大容量的内存，将很难运行Predictor压缩。
Stac：该算法查看数据流里面重复的字符串，然后使用一个比原来字符串要短的记号来标记以达到压缩的目的。Stac压缩算法对占用CPU的资源有较高要求，往往不被采用于高CPU利用率的路由器中。如果路由器本身的负载就比较重（超过40%），最好不要启用Stac压缩。

TCP头压缩配置

router(config-if)#ip tcp header-compression

当在接口上启用了TCP头压缩之后，接口的快速转发功能将会被自动关闭。如果在某些快速链路上（如E1）启用了TCP头压缩，将会造成路由器负载加重。因此TCP头压缩只适合在低速链路上使用。