[c-nsp] Spanning Tree help sought

[Christopher Gray]

Good day,

I'm new to Spanning Trees and have read up on them, but need advice and
guidance.  I have the manuals and can set STP up - it is the design that is
my concern.  My LAN is more complicated than this, but the following example
will help me explain.

I have four switches (A, B, C & D) linked in a loop comprising 1Gbps fibre.
Switch A is connected to a primary WAN router while switch C is connected to
the secondary WAN router - the two routers working in a simple HSRP
fail-over set.  I want to ensure that this loop will survive the failure of
any one link (e.g. if the link between A & B goes down, B will still be able
to connect to the primary router via C & D.

I currently have the STP path costs set to A=4, B=5, C=6 and D=7

Question 1: Does this make sense?  Should the "root bridge" (using Wikipedia
terminology) always be the one connected to the primary WAN router?  Does
STP work well when the WAN uplink fails over to the secondary or doesn't it
matter.

The switch configurations seem to show that other ports - e.g. those
connected to end-devices (printers / PCs) have an STP state of "forwarding".

Question 2: Should I set all non-uplink (interswitch) ports as "disabled"?

Many thanks

Chris