Scalability through symbolization

By stretch | Saturday, April 19, 2008 at 6:50 a.m. UTC

There are two types of network documentation which should not intermingle: design and inventory. Design documentation serves to convey the physical and logical layouts of a network, usually in the form of one or more diagrams. Inventory documentation serves to track details like unique addressing and serial numbers, and is best maintained in a spreadsheet or some other form of database.

Some people attempt to combine the two, and it never turns out pretty. The following excerpt is from a theoretical hybrid design-and-inventory drawing:

symbolization_before.jpg

While not necessarily an ugly drawing, there is a very serious flaw lurking just below the surface; this drawing will not scale. Currently only four hosts are pictured on the segment, but what if that network expands to twice the size? What about ten times? Fortunately, we can do away with some less useful details in the interest of scalability.

Note how each host is drawn separately for the sole purpose of displaying its IP address. Host addressing should be considered inventory data, and should be stored along with model, serial number, MAC address, and a plethora of other details in a separate database. Even port numbers could be considered inventory data in this instance, and need not be included on the drawing. With that in mind, we can simplify the drawing considerably without any significant loss of information:

symbolization_after.jpg

The segment is now identified by a cluster of simple icons; this same cluster can be used to symbolize any number of end hosts in a segment. By moving individual addressing to a separate source of documentation, we gain scalability yet still provide the segment subnet address and switch location. This level of detail is appropriate for the scope of the drawing.

About the Author

Jeremy Stretch is a network engineer living in the Raleigh-Durham, North Carolina area. He is known for his blog and cheat sheets here at Packet Life. You can reach him by email or follow him on Twitter.

Posted in Network Diagrams

Comments


Harold Morales (guest)
April 29, 2008 at 11:00 p.m. UTC

Hi Man..

your blog is just wonderful, I find a lot of interesting things and topics on it..

Regarding this post, do you know some sites and links where the network diagraming is taken into deep? i mean, the numbering, what symbols should i use, types of diagrams etc..?

Thanks in advanced..

Harold From Bogotá, Colombia (Here, is not time of war everyday)

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