HP Hub & Switch Management for OV-UX - Manual (Page 60)

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Managing Switches
Configuration
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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 a 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