STP - UplinkFast and root port delay timer


[UplinkFast](/stp-uplinkfast) is a Cisco proprietary enhancement to the original [Spanning Tree Protocol (STP)](/spanning-tree-protocol-stp) designed to improve convergence times. When a root port fails, UplinkFast allows a switch to quickly transition an alternate port to the forwarding state, reducing downtime. However, the [root port delay timer](/stp-uplinkfast-and-root-port-delay-timer) of 50 seconds (non-configurable) is employed when the original root port comes back up.

There are situations in which STP reconvergence will occur faster than the delay timer of 50 seconds.  This can depend on various factors:

1. **Platform Variability**: UplinkFast is not part of the original 802.1D STP design, so it is not strictly adhered to, and its implementation may vary across different Cisco platforms.
2. **STP Version Impact**: The behavior of UplinkFast can be affected by the STP version in use. For instance, [Rapid Spanning Tree Protocol (RSTP)](/stp-rstp-convergence-process) inherently reconverges quickly, rendering UplinkFast configurations less impactful.

Understanding these factors can help in optimizing network performance and ensuring quick recovery from link failures using UplinkFast.

## Links

https://networklessons.com/spanning-tree/spanning-tree-uplinkfast

STP - UplinkFast and reconvergence

SNMP walk

SPAN capturing control packets

SPAN multiple destination ports on Cisco IOS device

SPAN using VLANs as a source on a Nexus device

SPAN

SSH - domain-name prerequisite

SSH connectivity - troubleshooting

SSM Multicast Group Verification

STP - Aging time reduction with a TCN

STP - Aging time return to default

STP - BPDU Filter Use Cases

STP - BPDU generation and port roles

STP - BPDUGuard, BPDUFilter, and Portfast

STP - BPDUs on a switch where STP is disabled

STP - BPDUs, VLAN IDs, and PVST+

STP - Cost of last link added by receiving switch

STP - Disabling spanning-tree

STP - Dispute

STP - Factors to Consider When Choosing a Root Bridge

STP - Learning State

STP - MST CIST Root

STP - MST CST and CIST

STP - MST Virtual Bridge and its role in interfacing with other STP topologies

STP - MST and PVST+ selecting root port

STP - MST maps groups of VLANs

STP - MST region attributes

STP - MST viewed as a single switch by PVST+

STP - Max Age vs Message Age

STP - Multiple Spanning Tree (MST)

STP - Multiple types of STP on the same switch

STP - PVST+ and Rapid PVST+ interaction

STP - Per VLAN Spanning Tree plus (PVST+)

STP - RSTP BPDU Flags and their usage

STP - RSTP EdgePort

STP - RSTP Proposal Timer Operation

STP - RSTP convergence process

STP - RSTP port roles

STP - RSTP prerequisites for immediate move to forward state

STP - RSTP proposal-agreement process

STP - RSTP while timer cannot be observed

STP - RSTP while timer

STP - Root Inconsistency State

STP - Root Link Query (RLQ) BPDU

STP - Shortest Path Bridging (SPB)

STP - Time to select root bridge

STP - Topology Change Acknowledgement (TCA)

STP - UDLD and Fiber Links

STP - Understanding MST regional root identifier and proposal-agreement process

STP - UplinkFast

STP - bridge priority

STP - connecting one port to another port on the same switch

STP - determining the blocked port using port ID

STP - port identification

STP - port roles

STP - port states

STP - spanning-tree root primary command

STP - what bridge ID does the MST region use

STP - what is a topology change

STP BPDU Filter

STP BPDU Guard

STP BPDU Types

STP BPDU destination MAC address

STP Cost Calculation Methods

STP Loop Guard

STP Max Age

STP Message Age

STP PortFast Best Practice

STP Portfast Options

STP Root Bridge selection

STP Root Guard

STP Topology Change (TC) flag

STP Topology Change Timer

STP UDLD and Autonegotiation

STP UDLD

STP bridge priority values

STP changing link cost

STP configuring on EtherChannel

STP contents of a BPDU

STP cost long mode

STP cost short mode

STP determining blocked port using cost

STP direct vs indirect link failure

STP fine tuning the spanning tree protocol

STP how a switch identifies a BPDU

STP how to find the root bridge

STP interface type

STP prio nbr value

STP topology change process

Security - 802.1x with WLC and AAA server

Security - AAA for RESTCONF

Security - Best Practices for Repurposing Network Devices

Security - Cisco AnyConnect Secure Mobility Client

Security - Cisco Secure Client

Security - Cisco VPN Client

Security - Cisco VPN client software

Security - Diffie-Hellman groups

Security - Extensible Authentication Protocol over LAN (EAPOL)

STP - UplinkFast and reconvergence

Links

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