Using Expect to Configure Cisco Routers
Clay Lin
Changing the configuration on one Cisco router is a breeze - you
telnet to the router, enter the configuration line by line,
then you are done. But what about manually changing the
configurations on 200 routers? Not only is it time consuming, it is
also easy to make mistakes during this manual process.
Where I work, the network consists of more than 200 Cisco
routers interconnected by frame relay and ISDN wide area network
all over the U.S. continent. We used to change all the router
configurations by hand, and the entire task would take about a
month for two people to finish, not including the time to verify
accuracy. As a smart (or lazy?) administrator, I wanted to find a
way to automate this task.
Tools from Cisco
I first looked for the commercial-off-the-shelf (COTS) solutions
to help us. Two applications, ConfigMaker and CiscoWorks, from
Cisco are capable of dealing with configuration issues. The
ConfigMaker is a little program with a nice graphical user
interface (GUI) running on the Win95/NT platform. It is easy to
use, and it is free.
This solution does not fit our requirements in that:
- It does not work for Cisco 7000 series routers.
- It is primarily used to configure routers from scratch.
- It is best used for small to mid-sized (about 20-30 routers)
networks, according to Cisco's recommendation.
- It does not work with TACACS+, which is the
authentication/authorization mechanism we use for Cisco
routers.
CiscoWorks is a full-blown management tool for routers with a
lot of nice features and is recommended if you have a large number
of Cisco routers.
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