HP TopTools for Hubs and Switches - Manual (Page 73)

Group Policies
Advanced Switch Features
7-11
Figure 7-8. Advanced Switch Features Page
The problem of broadcast control is addressed in part by the use of two
features, Automatic Broadcast Control (ABC) and Internet Group
Management Protocol (IGMP).
Automatic Broadcast Control (ABC)
Automatic Broadcast Control (ABC) is a feature that controls broadcasts
through IP/IPX Broadcast Reduction. IP/IPX Broadcast Reduction reduces the
number of broadcasts propagated through the network.
Using ABC, the switch acts as a proxy server, replying to Address Resolution
Protocol (ARP) requests, Nearest Server Query (NSQ) requests, and
GetLocalTarget requests on behalf of the destination node. An ARP cache
(learned address table) is created for each subnet allowing the switch to proxy
reply with the resolved MAC address instead of forwarding the requests out
all ports. This limits the broadcasts within the switching domain. The Service
Advertising Protocol (SAP) table performs the same function in an IPX
network. By using these tables, the switch can resolve addresses for any node
in the network that it already knows about.