I'm trying to make an informed decision whether moving to a
multi-vendor best-of-breed makes sense for my organization.
This is obviously a complex question, so I am hoping to tap
some (figurative) "grey hair" advise from real-world
experiences for the general areas I should focus on in
making/justifying a decision.
Irwin Lazar <ILazar@burtongroup.com> writes:
We find the general trend is to go single-vendor whenever possible,
primarily to reduce support and management costs.
Engineers/Operators generally want single vendor, management
generally wants best of breed (to put pressure on suppliers).
That's ironic. I started out in a multi-vendor environment and for
the last two years I've been working in my first single-vendor
environment.
In all of the multi-vendor environments I worked in, it was the
management pushing for single-vendor (deeper discounts) with the
technical staff pushing for best-of-breed (reduced need for
out-of-hours support).
I think you should get the best of breed for core function devices
(provided you stay within budget). Non-core functions can be from the
same vendor as the core, as long as they are with-in a reasonable
delta from the best-of-breed.
- For WAN purposes, core function is core and distribution routers
and should be best of breed. Customer routers, switches, hubs,
etc. could come from the same vendor or a different one provided
they are of acceptable quality.
- For Enterprise/Data Center environments, core function is more
likely to be distribution router and/or switches, with other
other devices taking back seat in the decision making process.
Multi-vendor environments rule, but are harder to scale with a small
finite-clued staff. 
Single-vendor environments are easier to
scale in a manner disproportionate to the clue of the staff running
the network.
-jon