HP TopTools for Hubs and Switches - Manual (Page 75)

Group Policies
Advanced Switch Features
7-13
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 transmit RIPs or SAPs. When this feature
is not enabled, IPX RIP/SAP packets are forwarded to all ports.
Automatic IP Gateway Configuration
When Automatic IP Gateway Configuration is enabled, the switch will modify
replies from the DHCP server so that the Default Gateway IP address of client
becomes the client’s own IP address. This is useful in a multinetted
environment (where more than one IP network is configured in a single
broadcast domain).
See
Routing Information Protocol.
Internet Group Management Protocol (IGMP)
Multimedia and email applications need the ability to communicate to multiple
destinations efficiently. IP multicasting allows hosts to dynamically register
for sending or receiving multicast traffic.
The Internet Group Management Protocol is a method for automatically
controlling multicast traffic through the network. Using multicasting,
applications can send one copy of a packet addressed to a group of computers
that wish to receive it. This method is more efficient than sending a separate
copy to each node. Other advantages of multicasting include:
■ information delivered in a timely, synchronized manner because all desti-
nation nodes receive the same packet
■ information can be sent to destinations whose addresses are unknown
■ reduces the number of packets on the network because only one multicast
packet is sent.
IGMP uses multicast queriers and hosts that support IGMP to manage
multicast traffic on the network. It specifies how the host informs the network
that it is a member of a multicast group. A set of queriers and hosts that send
and receive data from the same set of sources is a multicast group.
The HP switches have a standards-based IGMP implementation. The switches
process IGMP packets by learning which of the switch’s interfaces are linked
to hosts that are members of multicast groups and multicast routers. It limits
multicast traffic by monitoring the IGMP traffic to learn which hosts are in
which multicast groups, then allowing IP multicast traffic to be sent only to
ports with valid host group members.
When a switch receives an IGMP packet, it updates the internal IP multicast
forwarding table with the IGMP membership read from that packet. The
switch then sends the packet to the ports with members of the destination
multicast group.