04 - Building Redundancy Switched Topology Flashcards
This instance of spanning tree is a Cisco enhancement of STP that provides separate 802.1D spanning-tree for each VLAN.
PVST+
This instance of spanning tree is the legacy standard, one spanning instance for entire network.
IEEE 802.1D STP
This instance of spanning tree maps multiple VLANs into same spanning-tree instance
802.1s (MSTP)
This instance of spanning tree improves convergence by adding roles to ports and enhancing BPDU exchanges.
802.1w (RSTP)
This instance of spanning tree is a Cisco enhancement of RSTP using PVST+
Rapid PVST+
What are the 3 types of BPDUs?
- Configuration BPDUS
- TCN BPDUs (topology change notification)
- TCA BPDUs (topology change ack)
How is a root bridge elected?
Based on lowest BID (combination of priority and MAC).
What are the fields in a BPDU frame?
- Protocol ID
- Version
- Message type
- Flags
- Root bridge ID
- Root path cost
- Send bridge ID
- Port ID
- Message age
- Maximum age
- Hello time
- Forward delay
What are the port roles?
- Root port
- Designated port
- Nondesignated port
- Disabled port
A _____ port will find the best path to the root bridge.
root
A ___ port will receive and forward frames toward the root bridge as needed.
designated
A ___ port does not forward (blocking)
nondesignated
A ____ port is a shutdown port
Disabled
What are the classic STP port states?
- Disabled
- Blocking
- Listening
- Learning
- Forwarding
A classic STP port state of ____ is administratively shut down.
Disabled
A classic STP port state of ____ receives BPDUs but cannot receive or transmit data.
Blocking
A classic STP port state of ____ is listening to see if there is a possibility that it will be selected as root or designated.
Listening
A classic STP port state of ____ after a time, forward delay in the listening state, the port is moved to ____.
Learning
A classic STP port state of ____ after another time. Forward delay in the learning state, the port is moved to ____.
Forwarding
What are the RSTP port states?
- Discarding
- Learning
- Forwarding
A RSTP port state of ____ prevents the forwarding of data frames, thus “breaking” the continuity of a Layer 2 loop.
Discarding
A RSTP port state of ____ accepts data frames to populate the MAC table to limit flooding of unknown unicast frames.
Learning
Spanning tree can be set in increments of …
4096
Default priority is ____ + VLAN number
32768
