What is BackboneFast?
The BackboneFast extension can dramatically decrease the convergence time of the Spanning Tree Protocol (STP) in the event of an Indirect link (a link in any other switch, which is not connected directly) failure, anywhere in the Spanning Tree Protocol (STP) Topology.
How do I enable UplinkFast?
To enable UplinkFast on a VLAN with switch priority configured, first restore the switch priority on the VLAN to the default value by using the no spanning-tree vlan vlan-id priority global configuration command. UplinkFast on an individual VLAN. The UplinkFast feature is supported only when the switch is running PVST.
What is Portfast UplinkFast and BackboneFast?
UplinkFast, Backbone Fast and Portfast are Cisco’s proprietary extensions to the Classic Spanning Tree Protocol (STP 802.1 D) algorithm. The purpose UplinkFast, Backbone Fast and Portfast are to reduce the time it takes Spanning Tree Protocol (STP) to converge after a link failure.
What is STP uplink fast?
UplinkFast is a Cisco specific feature that improves the convergence time of the Spanning-Tree Protocol (STP) in the event of the failure of an uplink. Do not use on switches without the implied topology knowledge of a alternative/backup root link typically to distribution and core switches in Cisco multilayer design.
What is the difference between UplinkFast and BackboneFast?
UplinkFast works by finding alternate ports for directly connected links. Similarly BackboneFast works on finding an alternate path when an indirect link to the root port goes down.
What is STP Bpdu guard?
BPDU Guard feature is used to protect the Layer 2 Spanning Tree Protocol (STP) Topology from BPDU related attacks. When a BPDU Guard enabled port receive BPDU from the connected device, BPDU Guard disables the port and the port state is changed to Errdisable state.
What is STP loop guard?
STP Loop Guard causes the non-designated port to go into the STP loop inconsistent state instead of the forwarding state. In the loop-inconsistent state, the port prevents data traffic through the link, therefore avoiding the loop creation.
How does STP BPDU work?
In a layer 2 Spanning Tree Protocol (STP) enabled network, Configuration BPDUs are generated from the Root Bridge (Root Switch) and flow outward along the active Paths and move away from the Root Bridge (Root Switch). Non-Root Switch only propagates the BPDUs generated by the Root Bridge (Root Switch) .
How does loop guard work?
STP Loop Guard blocks the entire channel in such a failure (by putting it into the loop-inconsistent state). Loop Guard does not work where the link has been unidirectional since it was first brought up. The port may never receive BPDUs but not recognize that there is a problem and become a designated port.
What are the different types of STP?
Spanning-Tree Protocol Types
| Protocol | Standard | Convergence |
|---|---|---|
| STP | 802.1D | Slow |
| PVST+ | Cisco | Slow |
| RSTP | 802.1w | Fast |
| Rapid PVST+ | Cisco | Fast |
When does backbone fast need to be enabled?
When used, backbone fast must be enabled on all switches in the network because backbone fast requires the use of the RLQ Request and Reply mechanism in order to inform switches of root path stability. The RLQ protocol is active only when backbone fast is enabled on a switch.
How does backbonefast work in BPDU spanning tree?
BackboneFast allows the blocked port on Switch C to move immediately to the listening state without waiting for the maximum aging time for the port to expire. BackboneFast then transitions the port on Switch C to the forwarding state, providing a path from Switch B to Switch A.
When to use backbone fast on CatOS switches?
Configure Backbone Fast for CatOS and Cisco IOS. When used, backbone fast must be enabled on all switches in the network because backbone fast requires the use of the RLQ Request and Reply mechanism in order to inform switches of root path stability. The RLQ protocol is active only when backbone fast is enabled on a switch.
Which is an example of the backbone fast feature?
The backbone fast feature proposes to save max_age (20 seconds). In order to do this, it ages out immediately after the port receive inferior BPDUs. With the previous example, STP invalidates information that becomes wrong because of an indirect link failure. In order to do this, it passively waits for max_age.