[c-nsp] Redundancy vs. Paranoia

[Andre Beck]

Hi,

On Thu, May 12, 2005 at 11:44:31AM -0600, John Neiberger wrote:
> I'm toying around with a handful of designs and I'm trying to get a
> better feel for the level of redundancy that would be considered sane so
> I thought I'd check here for some opinions. The designs in question
> generally deal with 6500s, 7600s, and 7200s, and the goal is to design a
> redundant routing and switching system with excellent failover
> characteristics. However, things can quickly get out of hand and I think
> they end up becoming more complex than necessary.
> 
> Here's one of the things I'm pondering: how do I decide which is
> "better", a single 6513 with dual sups and dual power supplies or two
> 6513s? At what point do you jump from a single box to two boxes? Does it
> make sense to even bother with making two separate boxes fully
> redundant?

In certain situations, it's better to have two switches with only one
CPU than to have one (or for that matter, two) with redundant CPUs
when one CPU fails. Interesting discussions of this kind are detailed
nicely in the two HA Campus Design papers at www.cisco.com/go/srnd so
you might have a look there.

HTH,
Andre.
-- 
                  The _S_anta _C_laus _O_peration
  or "how to turn a complete illusion into a neverending money source"

-> Andre Beck    +++ ABP-RIPE +++    IBH Prof. Dr. Horn GmbH, Dresden <-