In this post, I will be doing a brief commentary on creating and maintaining a physical port mapping spreadsheet. A port mapping spreadsheet is useful for keeping track of used/available ports on your network equipment, thoroughly documenting to which remote device each port connects, and generating configuration scripts to update port descriptions on the equipment.
You can download this article’s template file using the link to the right.
What to Document
The first question to ask when deciding to create a port mapping is which details should you record. The answer completely depends on your specific environment and what you plan to do with the documentation. Different requirements demand different data to be collected. I recommend you identify what you would like to do with this documentation before collecting and creating it. All that being said, the template linked to on this post contains a baseline of the most common data points which can provide a solid starting point.
This field details the layer-1 and layer-2 media and protocols used on the wire. Layer-1 can be things like RJ45, OM2 (SC), OS1 (LC), etc. Layer-2 can be things like Ethernet, PPP, or God forbid, Frame Relay.
Source Device Hostname & Port
These fields record the hostname and port information of the source device. Whenever possible, I will use the port name as it is seen in the configuration terminal of the device.
In case you are wondering the difference between the source device and the destination device, there really is no difference other than the fact that the focus of the document is always on the source device. In other words, the complete listing of ports for a device can be found in the section of the document where it is focused on as the source.
Patch Panel Fabric & Port
When there is infrastructure cabling used in-between the source and destination device: it is handy to note down which patch panel and port is used for the connection. The “Fabric” column can be replaced with “Panel Name” or anything else which specifies the infrastructure cabling extension set.
Destination Hostname & Port
This field defines the remote (non-focused) device and port where the connection terminates. When the port on the source device is empty and unused, these fields will be blank.
Destination Device Notes
These fields can be used for notations about the destination device including information about its role, purpose, and if the documented link is in an aggregated group (port-channel).
The scripting columns are used to generate configuration scripts using the information contained in the other columns. The scripting columns in the template are set up to generate port descriptions for Cisco based switches and will automatically detect when the different “Notes” fields are populated.
Make sure to visit the homepage for this series Network Documentation Series: Preamble and review the generic documentation tips listed there which apply to all network-related documents.