3Com CoreBuilder 3500, Implementation Manual, Page: 295 / 592

Broadcast Address 295
See the documentation for your workstation to determine whether you
can configure your workstation to use this protocol.
See RFC 1256 for detailed information about ICMP Router Discovery.
Broadcast Address
You can set a broadcast address for each defined IP interface. Your system
uses this broadcast address when forwarding directed broadcast packets,
and when advertising RIP packets.
When you define an IP interface, the broadcast address is
255.255.255.255. This is the default address.
Important
Considerations
Keep the following points in mind when you use broadcast address:
■
You cannot change the broadcast address for an IP interface if you
have already defined any RIP advertisement addresses.
■
If you are concerned with security, filter all inbound and outbound
broadcast traffic. Many hosts are set up to respond to an echo request
to their broadcast address with an echo reply, which can breach
security.
Directed Broadcast
A directed broadcast contains 1s in the host portion of the address field.
You can choose to have your system, on a per-interface basis, enable or
disable the forwarding of directed broadcast frames.
Important
Considerations
Keep the following points in mind when you use directed broadcast:
■
When your system receives a directed broadcast and the destination is
different from the interface on which it was received:
■
Your system forwards the directed broadcast if directed broadcast
is enabled
■
Your system drops the directed broadcast if directed broadcast is
disabled
■
Set the directed broadcast to reflect your security requirements. If you
have a critical IP interface, disabling directed broadcast can, for
example, protect against denial-of-service attacks by malicious users.