Making switch configuration changes is not as easy as it looks

September 6, 2013

In theory one of the advantages of the virtual approach to network drop wiring is that all you have to do to change a drop's networking is change your switch configuration for its port. But I feel that this ease is often somewhat of an illusion and I've come around to the view that switch configuration changes are not as easy in practice as they look (at least in many smaller environments).

To put it simply, making the change on the switch itself is the easy part. If the switch matters, you need to be able to deal with it dying; you need to be able to deploy a replacement on relatively short notice. This means that it's not enough to just change the live switch, you also need a way to get that change on to a replacement switch, generally either a backup of the configuration or actually mirroring the change on your hot spare switch. Depending on how much work is involved, this configuration replication can easily take more effort and time than the actual change itself.

Life is hopefully better on 'enterprise' grade switches, but our experience on inexpensive managed switches is that you do not really get features to make this easy (such as the ability to push a configuration on to the switch from another machine). Sometimes you can't even back up and restore the switch configuration (at this point you get to manually redo your change on your hot spare switch).

A closely related issue is dealing with the possibility of errors. If you have to change things directly on the switch it takes extra care to make sure that you are doing only the exact change you intended to do and backing out from an accidental change may be quite time consuming (in the worst case you get to check the entire switch configuration).

Written on 06 September 2013.
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Last modified: Fri Sep 6 01:31:38 2013
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