List of a useful tools for network architects

[Pavel Dimow <paveldimow () gmail com>]

Hi,

I am wondering what tools you consider most valuable when designing
big network from scratch or
perform a migration? For example I would like to know is there a tool
that will perform basic sanity checks
like network equipment without redundant link or without link at all...
I know that the one who design a network have to consider all this
issues but some automatic check will
save some time for sure...

Thank you.