LAN Switching & Wireless
When operating a network of switches
, what is the effect of turning off
An endless loop is created.
The Spanning Tree algorithm operates with the
One root bridge (switch) per network
One root port on
Root ports face the root bridge (exit port of the least
cost path to root bridge)
port on a root bridge is a designated port
There is one designated port for
doos) are layer 2 frames that identify the least
cost path to the root bridge and determine
which ports will forward frames in the Spanning Tree.
The Bridge ID (BID) is used to elect a root bridge. It is made up of
What are the three port roles of STP?
with the best path to the Root bridge
one per non
Receives and forwards
to the Root Bridge; one per LAN segment
Blocked to prevent loops in redundant networks
What are the three STP timers and what is there default length?
15 sec. (x2)
the five states of STP?
STP election process takes place
Transmits BPDUs but does not forward
Records MAC addresses but does not forward
Considered part of the active topology and now forwards frames
Administratively shut down, does not participate in STP
What is the first step in the STP process?
Election of a root bridge
number takes precedence)
Root bridge ID
version of STP that we use on Cisco equipment is PVST+, a proprietary version that supports
spanning tree instances on a per
RSTP vs. STP
RSTP utilizes edge ports to transition immediately from a blocked state to forwarding,
whereas STP requires all participating ports to transition through the max age and forward delay timers
Many commands are identical and RSTP BPDUs
are backwards compatible with STP.
What happens if an edge port receives a BPDU?
It immediately loses its edge status and becomes a normal Spanning Tree port in a blocking state.
What are the three types of links in RSTP?