Extracting graphs from ISIS

In this recipe, we'll write a Python PyEZ-based script, process-isis.py, to connect to one of our JUNOS OS devices and extract the ISIS link-state database. Because of the nature of link-state protocols like ISIS, a single router in the estate holds all of the information of the whole network. In this case, the link-state database knows about all other routers in the IGP domain and the adjacent devices to which they connect. We can use this information to help visualise our network.

Getting started

In order to complete this recipe, you'll need a Python 2.7 development environment and access to an ISIS-speaking JUNOS OS device. Ideally, you'll also have completed the previous recipe on visualizing graphs, so that you can provide the extracted information and obtain a visual representation of the protocol in return.

ISIS primer

ISIS is the link-state routing protocol of choice in the OSI suite. Though the OSI protocol suite never came to be at a global internet scale...