Module 5 Flashcards
What is Spanning Tree Protocol (STP) and what does it do
Why do we use STP?
allows redundancy while preventing loops at layer 2
same answer as “what are the benefits of STP”
What downsides does redundancy at layer 2 create?
broadcast storms, mac address table instability, and endless looping
What is the spanning tree algortihm (STA)
How does the STA create a loop-free topology?
Using STA, STP builds a loop-free topology in a four-step process, what is that process?
- Elect the root bridge
- elect the root ports
- elect designated ports
- elect alternate (blocked) ports
What is the default prioirty value for all cisco switches?
Default number is 32768.
Lower is better, and they are all multiples of 4096
What is the Bridge ID (BID)
The priority value of a switch
What happens if all of the prioirty numbers on the switches are the same?
STP will use the oldest MAC address value to base the priority on
What is a Bridge Protocol Data Unit (BPDU) and what does each BPDU contain?
what switches use to share information about themselves and thier connections and are used to elect the root birdge, root ports, designated ports, and alternate ports. Each BPDU contains a bridge ID (BID)
Explain the STP “elect the root bridge” process?
Explain the STP “elect the root ports” process
Explain the STP “elect designated ports” process
Explain the STP “elect alternate (blocked) ports” process
What are the three STP convergence timers and explain them
Hello Timer - the interval between BPDUs. Default is 2 sec but can be modified between 1-10 sec
Forward Delay Timer - time that is spent in the listening and learning state. default is 15 sec but can be made between 4-30 sec
Max Age Timer - max length of time that a switch waits before attempting to change to STP topology. Default is 20 sec but can be modified between 6-40 sec
WHat is RSTP
Rapid Spanning Tree Protocol or IEEE 802.1q is an evolution of STP that provides faster converngence than STP.
