This document provides a sample configuration for a serial tunnel (STUN) in Cisco routers. In the central router, one serial interface is connected to a front end processor (FEP); and, at the remote end, one Cisco router with two serial interfaces are connected to two different controllers.
There are no specific requirements for this document.
This document is not restricted to specific software or hardware versions.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
For more information on document conventions, see the Cisco Technical Tips Conventions.
In this section, you are presented with the information to configure the features described in this document.
This document uses the network setup shown in this diagram:
This document uses these configurations:
stun peer-name 18.104.22.168 stun protocol-group 9 sdlc interface serial 0 encapsulation stun stun group 9 stun route address c1 tcp 22.214.171.124 stun route address c2 tcp 126.96.36.199 interface loopback 0 ip address 188.8.131.52 255.255.255.0
stun peer-name 184.108.40.206 stun protocol-group 9 sdlc interface serial 0 encapsulation stun stun group 9 stun route address c1 tcp 220.127.116.11 interface serial 1 encapsulation stun stun group 9 stun route address c2 tcp 18.104.22.168 interface loopback 0 ip address 22.214.171.124 255.255.255.0
Note: Although not shown above, IP routing is assumed to be configured and working properly.
The above diagram and configurations do not show any clock source. You must provide one, otherwise the serial interfaces do not come up. There are a number of options available. The most common one is to use a DCE cable on the router side and add this command under the serial interface:
The other end of the connection then uses a DTE cable.
Another option is to use a modem eliminator that supplies the clocking and then use DTE cables on both ends of the connection. This method works for router to router, router to Host, and router to Controller connections. Nonreturn to zero (NRZ) or nonreturn to zero inverted (NRZI) encoding on the STUN interfaces must match end device encoding; the router defaults to NRZ.
There is currently no verification procedure available for this configuration.
There is currently no specific troubleshooting information available for this configuration.
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Refer to Cisco Technical Tips Conventions for information on conventions used in this document.