Legacy support: Serial tunneling (STUN)

How to transport non-IP based protocol over the IP network? Example a pc wants to send serial data to remote pc which is receiving only serial data over the WAN link, the WAN could be a frame-relay.

Cisco provides a tunneling technique known as serial tunneling or STUN in short. I could not test the configuration because¬† I took the wrong serial cables for the second pc…

My objective is simple, PC on the left is able to send serial data over to PC on the right, I could use hyperterminal or modbus simulator to proof the configuration.

For ease of testing, back to back frame-relay is used.

Back-to-back frame relay

interface Serial0/1
bandwidth 64
no ip address
encapsulation frame-relay
no keepalive
clock rate 64000

interface Serial0/1.300 point-to-point
ip address
frame-relay interface-dlci 300

Configuration except for the ip address is the same for both routers.

STUN configuration

stun peer-name
stun protocol-group 1 sdlc

interface Serial0/2
mtu 2104
no ip address
encapsulation stun
no shutdown

clock rate 64000

bandwidth 64
stun group 1
stun route address C1 interface Serial0/1 dlci 300

The stun peer-name can be the reliable ip address of a loopback address, since loopback does not go down unless the router is turned off. The configuration except for stun peer-name is the same for both routers.

This configuration is yet to be tested, because I have brought back incorrect cable.


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