When connecting a serial cable to the of the router, clocking is provided by an external device, such as a CSU/DSU device. A CSU/DSU (Channel Service Unit/Data Service Unit) is a digital-interface device used to connect a router to a digital circuit. The router is the DTE (Data Terminal Equipment) and the external device is the DCE (Data Communications Equipment), where the DCE provides the clocking.

How to Configure EIGRP on Cisco Router in GNS3? – In this article, we have communicated two different networks using the Cisco EIGRP routing protocol. When configuring EIGRP, you must configure the Wild Card Mask address correctly in the network command.

However, in some cases we might connect two routers back-to-back using the routers’ serial interfaces (Example: Inside the router labs). Each router is a DTE by default.

The cable decides which end to be DCE or DTE and it is usually marked on the cable. The picture below shows back to back cable. If is not marked, we can use the 'show controller' command to determine the interface is DTE or DCE. Since clocking is required to enable the interface, one of the two routers should function as DCE and should provide clocking. This can be done by using the 'clock rate' command, from the.

To find the possible clock rate values, get the command help by using a question mark after the 'clock rate' from the serial interface configuration mode, as shown below. Router(config-if)# clock rate? The output for above command is shown below. R1> R1>enable R1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R1(config)#interface serial 1/0 R1(config-if)#clock rate?

With the exception of the following standard values not subject to rounding, 1200 2400 4800 9600 0 0 0 1232 accepted clockrates will be bestfitted (rounded) to the nearest value supportable by the hardware. DCE clock rate (bits per second) These values are in bites per second. You can find the possible values by using help.

Router(config)# interface s0/1 Router(config-if)# clock rate 64000 All interfaces have a bandwidth value assigned to them. This is used by certain routing protocols, such as,, and, when making routing decisions. For LAN-based interfaces, the speed of the interface becomes the bandwidth value (In kilobits per second (Kbps)). Balabolka text to speech voices.

However, on synchronous serial interfaces, the bandwidth defaults to 1,554Kbps and this is not related with the clock rate set. To change the bandwidth value for an interface, use the bandwidth command: Router(config)# interface s0 Router(config-if)#bandwidth 64.