What are the Serial Interface Commands

What are the Serial Interface Commands

To configure a serial interface, there are a couple of specifics that need to be discussed. Typically, the interface will be attach.

1. You configure a DCE serial interface with the clock rate command. You will need to go

to a router that has a DCE connection.


Router#config t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#int s0
Router(config-if)#clock rate ?
Speed (bits per second)
1200
2400
4800
9600
19200
38400
56000
64000
72000
125000
148000
250000
500000
800000
1000000
1300000
2000000
4000000

<300-4000000> Choose clockrate from list above



Router(config-if)#clock rate 64000
%Error: This command applies only to DCE interfaces
Router(config-if)#int s1

Router(config-if)#clock rate 64000



It does not hurt anything to try and put a clock rate on an interface. Notice that the clock

rate command is in bits per second.


2. The next command you need to understand is the bandwidth command. Every Cisco router
ships with a default serial link bandwidth of a T1, or 1.544Mbps. However, understand that this
has nothing to do with how data is transferred over a link. The bandwidth of a serial link is used
by routing protocols such as IGRP, EIGRP, and OSPF to calculate the best cost to a remote

network. If you are using RIP routing, then the bandwidth setting of a serial link is irrelevant.



Router(config-if)#bandwidth ?
<1-10000000> Bandwidth in kilobits
Router(config-if)#bandwidth 64


Notice that unlike the clock rate command, the bandwidth command is configured in

kilobits.