Ch 2 - RSTP Flashcards
Rapid Spanning Tree Protocol
What is the IEEE protocol for RSTP
802.1w as an amendment to 802.1D. Later in 2004 was included in 802.1D known as 802.1d-2004 Loc: 2867
What does RSTP call the ‘Blocking State’?
Discarding State Loc: 2908
What is the RSTP Alternate Port?
Replaces the Root Port when the Root Port fails. Loc: 2942
What is the RSTP Backup Port?
Replaces the Designated Port when the Designated Port fails.
What is the RSTP Disabled Port?
Port that is admin’ed down. Loc: 2899
In RSTP what is a Point-to-point Link?
A link with exactly two devices on it running full duplex without portfast configured. Loc: 3004
In RSTP, what is a Point-to-point port?
The ports that connect to a point-to-point link. Loc: 3004
In RSTP, what is a Point-to-point Edge port?
A type of point-to-point port that connects to a single endpoint at the edge of the network running full duplex with portfast enabled.
in RSTP, what is a Shared Port?
A port that connects to a hub and runs half-duplex.
What is Etherchannel?
A connection that combines multiple parallel segments of equal speed (up to eight) between the same pair of switches, bundled into an EtherChannel. Loc: 3004
What is PortFast?
PortFast allows a switch to immediately transition from blocking to forwarding, bypassing listening and learning states. Can only be used on links with no bridges, switches, or other STP-speaking devices connected. Loc: 3032
What is BPDU Guard?
Prevents an unauthorized switch from connecting to a port and taking over Root Bridge. When configured on a switchport it disables the port if any BPDUs are received on it. Also prevents an unauthorized switch from connecting to a port running PortFast. Loc: 3032
In RSTP how long is the MaxAge timer?
3 times the Hello timer. Default is 6 seconds.
What are the 5 roles ports play in RSTP?
- Root Port
- Alternate Port
- Designated Port
- Backup Port
- Disabled Port
What qualifies a port to be an Alternate Port?
Must receive Hello’s from the same Root Switch as the existing Root Port
What are the steps a switch goes through to change from a failed Root Port to its Alternate Port?
- Root Port fails
- Switch confirms with its neighbor that it is about to change to its Root Port from the failed port to the Alternate Port as new Root Port.
- Neighbor flushes the required MAC entries
- Failed RP changes to Disabled Role and Alternate becomes RP
- New Root Port begins forwarding immediately.
When Alternate Port takes over for a Failed RP does it have to wait for any timers?
No.
Does RSTP have a Listening State?
No
What are the 3 Port States in RSTP?
- Discarding
- Learning
- Forwarding
What does RSTP do when there is a topology change?
- RSTP switches tell each other there has been a Topology Change and to Flush all MAC table entries that might cause a loop.
- Ports that were formerly Discarding can transition to Forwarding without a wait.
What are the 3 RSTP Link Types?
- Point-to-Point
- Point-to-Point Edge
- Shared
What does RSTP do differently on Shared Ports/Links?
RSTP converges more slowly on Shared Ports
What is the criteria RSTP uses to classify a port as a Point-to-Point Edge Port?
- Running at Full Duplex
- Has Portfast configured
What is the criteria RSTP uses to classify a port as a Point-to-Point Port?
- The port is running at Full Duplex
- The port does NOT have Portfast configured
What is the criteria RSTP uses to classify a port as a Shared Port
Any port running at Half Duplex.
If a port has Portfast configured what else should be added to that port?
BPDU Guard
