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。
1.有关命令
端口设置
注:1.以下给出一个显示Cisco同步串口状态的例子.
Router#show interface serial 0
Serial 0 is up, line protocol is up
Hardware is MCI Serial
Internet addre is 150.136.190.203, su et mask is 255.255.255.0
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Enca ulation HDLC, loo ack not set, keepalive set (10 sec)
Last i ut 0:00:07, output 0:00:00, output hang never
Output queue 0/40, 0 dro i ut queue 0/75, 0 dro
Five minute i ut rate 0 bits/sec, 0 packets/sec
Five minute output rate 0 bits/sec, 0 packets/sec
16263 packets i ut, 1347238 bytes, 0 no buffer
Received 13983 broadcasts, 0 runts, 0 giants
2 i ut errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort
22146 packets output, 2383680 bytes, 0 underru
0 output errors, 0 collisio , 2 interface resets, 0 restarts
1 carrier tra itio
2. 举例
设置如下：
Router1:
interface Serial0
ip addre 192.200.10.1 255.255.255.0
clockrate 1000000
Router2:
interface Serial0
ip addre 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: 
注: 1. 当链路为T1时,cha el-group编号为0-23, Timeslot范围1-24; 当链路为E1时, cha el-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 e1
e1 0/0 is up.
A lique type is Cha elized E1 - u alanced
Framing is CRC4, Line Code is HDB3 No alarms detected.
Data in current interval (725 seconds ela ed):
0 Line Code Violatio , 0 Path Code Violatio
0 Slip Secs, 0 Fr Lo Secs, 0 Line Err Secs, 0 Degraded Mi
0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
Total Data (last 24 hours) 0 Line Code Violatio , 0 Path Code Violatio ,
0 Slip Secs, 0 Fr Lo Secs, 0 Line Err Secs, 0 Degraded Mi ,
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 t
Building configuration...
Current configuration:
!
version 11.2
no service udp-small-servers
no service tcp-small-servers
!
hostname shanxi
!
enable secret 5 $1$XN08$Ttr8nfLoP9.2RgZhcBzkk/
enable pa word shanxi
!
!
ip su et-zero
!
controller E1 0
framing NO-CRC4
cha el-group 0 timeslots 1
cha el-group 1 timeslots 2
cha el-group 2 timeslots 3
!
interface Ethernet0
ip addre 133.118.40.1 255.255.0.0
media-type 10BaseT
!
interface Ethernet1
no ip addre
shutdown
!
interface Serial0:0
ip addre 202.119.96.1 255.255.255.252
no ip mroute-cache
!
interface Serial0:1
ip addre 202.119.96.5 255.255.255.252
no ip mroute-cache
!
interface Serial0:2
ip addre 202.119.96.9 255.255.255.252
no ip mroute-cache
!
no ip cla le
ip route 133.210.40.0 255.255.255.0 Serial0:0
ip route 133.210.41.0 255.255.255.0 Serial0:1
ip route 133.210.42.0 255.255.255.0 Serial0:2
!
line con 0
line aux 0
line vty 0 4
pa word shanxi
login
!
end
