HDLC协议有关命令与配置

HDLC是CISCO路由器使用的缺省协议，一台新路由器在未指定封装协议时默认使用HDLC封装。本博文将为您详细介绍HDLC协议的有关命令及配置。HDLC协议是一种简单、高效的点到点链路协议，主要用于点到点连接的路由器间的通信。HDLC协议有 Cisco HDLC 和 ISO DHLC 两种，两者不能兼容。锐捷路由器的同步串行口默认封装Cisco HDLC，
所以锐捷路由器可以和Cisco路由器直接相连，但如果把锐捷路由器和不支持Cisco HDLC的路由器相连，就需要采用其它协议(如PPP)。1.有关命令端口设置498)this.w
idth=498;' onmousewheel = 'javascript:return big(this)' src="http://s4.51cto.com/wyfs01/M01/32/1F/wKioJlJ4TT2RduGdAAA49PZkijg120.jpg" width="450" border="0" height="93" alt="" />注:1.以下给出一个显示Cisco同步串口状态的例子.Router#show interface serial 0Serial 0 is up, line protocol is upHardware is MCI SerialInternet address is 150.136.190.203, subnet mask is 255.255.255.0MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255Encapsulation HDLC, loopback not set, keepalive set (10 sec)Last input 0:00:07, output 0:00:00, output hang neverOutput queue 0/40, 0 drops; input queue 0/75, 0 dropsFive minute input rate 0 bits/sec, 0 packets/secFive minute output rate 0 bits/sec, 0 packets/sec16263 packets input, 1347238 bytes, 0 no bufferReceived 13983 broadcasts, 0 runts, 0 giants2 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort22146 packets output, 2383680 bytes, 0 underruns0 output errors, 0 collisions, 2 interface
resets, 0 restarts1 carrier transitions2.　举例498)this.width=498;' onmousewheel = 'javascript:return big(this)' src="http://s3.51cto.com/wyfs01/M02/32/1F/wKioJlJ4TWvyhePkAAAu6PPw_Gs024.jpg" width="389" border="0" height="80" alt="" />设置
如下：Router1:interface Serial0ip address 192.200.10.1 255.255.255.0clockrate 1000000Router2:interface Serial0ip address 192.200.10.2 255.255.255.0!3.　举例使用E1线路实现多个64K专线连接.相关命令:498)this.width=498;' onmousewheel = 'javascript:return big(this)' src="http://s1.51cto.com/wyfs01/M01/32/21/wKioOVJ4TYDzWw3IAABUbaXjltc828.jpg" width="452" border="0" height="132" alt="" />注: 1. 当链路为T1时,channel-group编号为0-23, Timeslot范围1-24; 当链路为E1时, channel-group编号为0-30, Timeslot范围1-31.2.使用show controllers e1观察controller状态,以下为帧类型为crc4时controllers正常的状态.Router# show controllers e1e1 0/0 is up.Applique type is Channelized E1 - unbalancedFraming is CRC4, Line Code is HDB3　No alarms detected.Data in
current interval (725 seconds elapsed):0 Line Code Violations, 0 Path Code Violations0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail SecsTotal Data (last 24 hours) 0 Line Code Violations, 0 Path Code Violations,0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs以下例子为E1连接3条64K专线, 帧类型为NO-CRC4,非平衡链路,路由器具体设置如下:shanxi#wri tBuilding configuration...Current configuration:!version 11.2no service udp-small-serversno service tcp-small-servers!hostname shanxi!enable secret 5 $1$XN08$Ttr8nfLoP9.2RgZhcBzkk/enable password shanxi!!ip subnet-zero!controller E1 0framing NO-CRC4channel-group 0 timeslots 1channel-group 1 timeslots 2channel-group 2 timeslots 3!interface Ethernet0ip address 133.118.40.1 255.255.0.0media-type 10BaseT!interface Ethernet1no ip addressshutdown!interface Serial0:0ip address 202.119.96.1 255.255.255.252no ip mroute-cache!interface Serial0:1ip address 202.119.9
6.5 255.255.255.252no ip mroute-cache!interface Serial0:2ip address 202.119.96.9 255.255.255.252no ip mroute-cache!no ip classlessip route 133.210.40.0 255.255.255.0 Serial0:0ip route 133.210.41.0 255.255.255.0 Serial0:1ip route 133.210.42.0 255.255.255.0 Serial0:2!line con 0line aux 0line vty 0 4password shanxilogin!end3、配置keepalive时间HDLC每隔10秒钟就互相发送链路探测的协商报文(KeepAlive报文)，用于探查链路是否中断，每次收发的报文按序号递增，序号失序则链路中断。当接口连续3次(数据包速率超过1000packets/s时为6次)没有收到对方对自己的递增序号
的确认时，HDLC协议就把链路状态由Up转变为Down，链路将不可用。HDLC协议可配置的参数只有Keepalive的间隔时间，缺省值是10秒。可以根据链路的流量来修改这个值。1、配置keepalive时间：Router(config)#interface interface-idRouter(config-if)#keepalive secondsinterface 命令用于指定要配置的接口，必须是Serial口，interface-id是接口号。keepalive 命令设置keepalive时间，seconds是以秒为单位的时间值。2、忽略keepalive探查：Router(config)#interface interface-idRouter(config-if)#no keepalive使用 no keepalive 命令表示不进行HDLC链路状态探查，即不发送keepalive报文，也不处理收到的keepalive报文。配置举例：R1>enable R1#
configure terminal R1(config)#interface s0/0 R1(config-if)#encapsulation hdlc R1(config-if)#keepalive 15R2>enable R2#configure
terminal R2(config)#interface s0/0 R2(config-if)#encapsulation hdlc R2(config-if)#keepalive 15注意：你必须保证相连两
端的keepalive时间相同。