Hello Silvia,

the revised nonlinear costs should have been introduced in 1998 802.1D revision of the protocol.

see

http://en.wikipedia.org/wiki/IEEE_802.1D

I never see a switch using the old linear costs.

According to first edition of CCNP Switching by Hucaby:

>> Be aware that not all versions of the Catalyst Supervisor code use the newer non-linear scale by

default. For example, Catalyst 5000 versions 2.4 and lower use the older linear scale. Catalyst

5000 versions 3.1 and higher, Catalyst 4000 (all versions), and Catalyst 6000 (all versions) use

the non-linear scale by default.

Our oldest C5500 catos switches have 5.5.x CatOS and use nonlinear costs.

Hope to help

Giuseppe