
An RLQ (Root Link Query) message is a type of [BPDU](/stp-bpdu-types) used in [Spanning Tree Protocol (STP)](/spanning-tree-protocol-stp).  Identifying an RLQ message using a packet sniffer such as [Wireshark](/wireshark) can be challenging because it is indistinguishable from other BPDUs based solely on its content.  RLQ BPDUs are control BPDUs that include TLVs (Type-Length-Values) within the BPDU payload, which allow a switch to recognize the BPDU as an RLQ message. Therefore, while RLQ BPDUs may be present, they may not be easily identifiable without examining the TLVs.

RLQs are used in the context of STP with features such as BackboneFast as well as in the event of a [topology change](/stp-topology-change-process) or in the context of [RSTP](/stp-rstp-convergence-process).

## Links

https://forum.networklessons.com/t/spanning-tree-backbone-fast/1141/26?u=lagapidis

https://networklessons.com/spanning-tree/spanning-tree-backbone-fast

STP - Root Link Query (RLQ) BPDU

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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

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