Automatic network discovery and documentation

NetBrain is a famous software that allows network discovery (and management). Let’s focus now on network discovery and documentation: we want to automatically discover network devices, and how they’re connected, and store everything into a version control repository (GIT/CVS).

So we want to:

discover all network devices;
map how they’re connected;
track changes automatically;
store everything into a version control repository (GIT/CVS);
visualize any updated map with a simple browser.

How we can solve the above problem:

we assume all devices by Cisco, so we can use CDP;
we can get CDP data via SNMPv3;
we can build a (source, destination) topology;
we can store the topology into a revision control repository (GIT/CVS);
we can use jsPlumb to render the (source, destination) topology into a web page.

netdoc

netdoc is the small experiment I wrote to solve the problem. It contains two Python scripts:

netdiscover.py: to discover network devices via SNMPv3 and generates two .ini files:
- discovered_nodes.ini: contains all network devices with some additional information
- discovered_connections.ini: contains all network connections with some additional information
netplot.py: to plot a web page from the above .ini files.

.ini files can be stored in a revision control repository. Running netconf

Currently, netdoc is a POC script, so maybe it can work on your infrastructure, maybe it won’t. To start it, run:

./netdiscover.py -u snmpv3user -p snmpv3password -h 10.1.1.4 -h 10.1.1.5 -h 10.1.1.6

The discovered_nodes.ini file contains all CDP discovered devices in the following form:

[AccessServer]
id = AccessServer
image = router.svg
disabled = false
platform = cisco 2610

The title is the CDP neighbor ID (usually the hostname); other attributes are:

id: the CDP neighbor ID (usually the hostname)
image: an image used to display the node in the web page
disabled: true if missing during the last scan
platform: the CDP neighbor platform

The discovered_connections.ini file contains all CDP discovered connections in the following form:

[AccessServer:e0/0-switch.example.com:gi2/0/46]
source = AccessServer
source_if = e0/0
destination = swipd002.campus.infocert.it
destination_if = gi2/0/46
disabled = false