y/n) [n]? y VLANs 1-4094 bridge priority set to 32768. The port cost of all bridge ports set to default value. The portvlancost of all bridge ports set to default value. uplinkfast all-protocols field set to off. uplinkfast disabled for bridge. The values are not necessarily set to what they were before I enabled UplinkFast- they are returned to their defaults. When configuring UplinkFas on IOS switches, there are no scary messages like there are in CatOS: Cat-3550(config)# spanning-tree uplinkfast Cat-3550(config)# That's it. Simple! But don't let the simplicity fool you-enabling UplinkFast changes priorities in IOS, too. Unlike in CatOS, however, disabling the feature in IOS (via no spanning-tree uplinkfast) automatically resets the priorities to their defaults. Again, this might not be what you want or expect, SO be careful. BackboneFast When a switch receives a BPDU advertising a root bridge that's less desirable than the root bridge it already knows about, the switch discards the BPDU. This is true for as long as the switch knows about the better root bridge. If the switch stops receiv- ing BPDUs for the better root bridge, it will continue to believe that that bridge is the best bridge until the max_age timeout is exceeded. max_age defaults to 20 seconds. Figure 8-7 shows a network with three switches. All of these switches are core or dis- tribution switches, though they could also be access-layer switches. Switch A is the root bridge. Through normal convergence, the F0/2 port on Switch C is blocking, while all the others are forwarding. Say an outage occurs that brings down the F0/3 link between Switch A and Switch B. This link is not directly connected to Switch C. The result is an indirect link failure on Switch C. When Switch B recognizes the link failure, it knows that it has no path to the root, and starts advertising itself as the root. Until this point, Switch B had been advertising BPDUs showing the more desirable Switch A as the root. Switch C still has that information in memory, and refuses to 