link avoidance

[Randy Bush <randy () psg com>]

a fellow researcher wants

    > to make the case that in some scenarios it is very important for a
    > network operator to be able to specify that traffic should *not*
    > traverse a certain switch/link/group of switches/group of links
    > (that's true right?). Could you give some examples? Perhaps point
    > me to relevant references?

if so, why? security?  congestion?  other?  but is it common?  and, if
so, how do you do it?

randy