HP Hub & Switch Management for OV-UX - Manual (Page 59)

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Managing Switches
Configuration
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For example, if User A sends out a broadcast message to connect to its
server, the request is sent out of all ports on the switch. When the server
responds to User A, the switch intercepts the response and learns that the
server is on that port. When User B sends a request to the same server, the
switch already knows which port that server is on and sends that
information to User B, just as if the server had responded to the request.
User B’s request is not broadcast out any of the switch ports.
Enabling Broadcast Control for IP
The IP protocol uses Address Resolution Protocol (ARP) packets to find the
MAC address of a node that corresponds to the network layer address. When
Broadcast Control is enabled, the switch intercepts the ARP packet on its
way to the destination node. If this destination is unknown to the switch, the
switch floods the ARP request to all ports. When the destination port
responds, the switch stores information about the destination MAC address
and layer 3 address in its ARP cache. This information allows the switch to
proxy a reply containing the MAC address of a destination to the source of
an ARP request. The source can then send a unicast packet directly to the
destination. The amount of broadcast traffic has been decreased.
Automatic IP RIP Control. To further reduce broadcast traffic, you can
check Automatic IP RIP Control. IP RIP packets are sent out periodically
(every 30 seconds) to distribute routing information. By enabling Automatic
IP RIP Control, the switch will only forward RIP packets out the ports on
which RIP packets have been received. Since routers are the only devices
that generate RIP packets, this ensures that RIP packets are only sent out
ports with routers attached to them. When this feature is not enabled, IP RIP
packets are forwarded to all ports.
Enabling Broadcast Control for IPX
The IPX protocol broadcasts all of its known routes and services every
minute by using IPX, RIP and Service Advertising Protocol (SAP) packets.
When servers are booted up, they advertise their services using SAP. These
frames must be forwarded by routers, which maintain a database of this
information, allowing clients on the network to obtain the internetwork
addresses of the servers where they can access services.
Automatic IPX RIP/SAP Control. To further reduce network traffic, you
can check the Automatic IPX RIP/SAP Control check box. The switch will
intercept RIPs and SAPs, broadcasting them only to ports where IPX routers
or servers have been detected, or to ports that have been configured to