VLAN Advertisement Protocol (VAP)
Page 21-8

VLAN Advertisement Protocol (VAP)

The VLAN Advertisement Protocol (VAP) is an interswitch protocol that keeps the VLAN
membership databases stored on switches in sync and enables the auto-discovery of network
nodes. VAP is useful when you want all VLANs to communicate over a backbone, but do not
want locally connected devices to receive all backbone traffic.
In order for a switch to participate in VAP exchanges, VAP must be enabled through a soft-
ware configuration command. The switch does not need to have attached devices that are a
part of all groups and VLANs for which VAP information is exchanged; however, all groups
and VLANs must be defined on each switch.
Each switch in a network maintains an AutoTracker database. This database is built by
observing traffic that matches user-configured policies. The VAP protocol reads this database
on all switches and then advertises entries in the database to all other switches in the
network.
VAP Exchanges Between Switches
VAP updates nodes on any new entries in AutoTracker databases every 60 seconds.
VAP also stores information in its own database. Currently this information is used by SNMP-
based network management software. The database contains information on VLAN member-
ship; it maps each learned MAC address to a group and to any associated VLANs. This data-
base can contain information on up to 40,000 MAC addresses.
VAP packets sent
between switches.
VAP packets sent
between switches.