13-28
Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter13 Configuring VLANs
Configuring VMPS
Configuring VMPS
The VLAN Query Protocol (VQP) is used to support dynamic-access ports, which are not permanently
assigned to a VLAN, but give VLAN assignments based on the MAC source addresses seen on the port.
Each time an unknown MAC address is seen, the switch sends a VQP query to a remote VMPS; the query
includes the newly seen MAC address and the port on which it was seen. The VMPS responds with a
VLAN assignment for the port. The switch cannot be a VMPS server but can act as a client to the VMPS
and communicate with it through VQP.
These sections contain this information:
•“Understanding VMPS” section on page 13-28
•“Default VMPS Client Configuration” section on page13-29
•“VMPS Configuration Guidelines” section on page13-30
•“Configuring the VMPS Client” section on page13-30
•“Monitoring the VMPS” section on page13-33
•“Troubleshooting Dynamic-Access Port VLAN Membership” section on page13-33
•“VMPS Configuration Example” section on page13-33

Understanding VMPS

Each time the client switch receives the MAC address of a new host, it sends a VQP query to the VMPS.
When the VMPS receives this query, it searches its database for a MAC-address-to-VLAN mapping. The
server response is based on this mapping and whether or not the server is in open or secure mode. In
secure mode, the server shuts down the port when an illegal host is detected. In open mode, the server
simply denies the host access to the port.
If the port is currently unassigned (that is, it does not yet have a VLAN assignment), the VMPS provides
one of these responses:
•If the host is allowed on the port, the VMPS sends the client a vlan-assignment response containing
the assigned VLAN name and allowing access to the host.
•If the host is not allowed on the port and the VMPS is in open mode, the VMPS sends an
access-denied response.
•If the VLAN is not allowed on the port and the VMPS is in secure mode, the VMPS sends a
port-shutdown response.
Step14 Repeat Steps 9 through 13 on the other configured trunk interface on
Switch A, and set the spanning-tree path cos t to 3 0 for VLAN s 8, 9 , and
10.
Step15 exit Return to privileged EXEC mode.
Step16 show running-config Verify your entries. In the display, verify that the path costs are set
correctly for both trunk interfaces.
Step17 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose