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Cisco VQP / VMPS
Cisco's VLAN Query Protocol (VQP) facilitates dynamic VLAN assignments by querying VLAN Management Policy Servers (VMPS). Operating primarily over UDP, it allows network switches to determine which VLAN a device should belong to based on its MAC address. This aids in automated network policy enforcement and scalable, dynamic network segmentation..
Overview:
Cisco VLAN Query Protocol (VQP) is employed on Cisco Catalyst switches to automate VLAN assignments for network devices. It typically leverages UDP port 1589 to communicate queries from a switch acting as a client to a VLAN Management Policy Server (VMPS). The VMPS responds with VLAN configuration details based on the device's MAC address.
Operation:
When a device connects to a switch port set for dynamic VLAN membership, the switch sends a VQP query over UDP 1589 to the VMPS. The request includes the device's MAC address and port information. The VMPS server determines which VLAN the device belongs to, instructing the switch to assign the VLAN dynamically. This streamlines network management in environments with many devices or frequent changes.
Deployment:
VQP and VMPS are proprietary Cisco technologies and generally used within Cisco-centric infrastructures. While VQP simplifies VLAN administration, it lacks encryption or strong authentication mechanisms. Over time, industry best practice has shifted towards more secure options like IEEE 802.1X with dynamic VLAN assignment via RADIUS, which provide enhanced security and flexibility.