Rapid Transitions - Avaya 2330 Manual

Layer 2 fundamentals

Rapid transitions

On a port connected to no other bridge, Spanning Tree PortFast brings the port up more quickly
following device initialization or a spanning tree change.
For example, in the following figure, ports A1, B1, B2 are connected to end stations. These
ports do not participate in the Spanning Tree port selection. These ports can, therefore, go
directly to the spanning tree forwarding state (skipping the listening and learning states).
Figure 11: Enabling rapid transitions in a network
Important:
Enabling PortFast does not disable spanning tree on an interface. See
Filter on page 39 for more information.
PortFast is intended for access ports where only one device is connected to the router or switch
(as in workstations with no other spanning tree devices). If you configure PortFast on a port
that is connected to another bridge, there is the possibility of forming a loop. This can be
prevented with the help of the Bridge Protocol Data Unit (BPDU) Guard feature.
38 Configuration — Layer 2 Ethernet
Comments? infodev@avaya.com
PortFast BPDU
July 2013