|
To configure the helper address,
identify the router interface that will be receiving the broadcasts
for UDP services. In interface configuration mode, use the ip
helper-address command to define
the address to which UDP broadcasts for services should be
forwarded.
By default, the ip
helper-address command forwards
the eight UDP services shown in Figure .
What if Company XYZ needs to forward requests for a service not on
this list? The Cisco IOS provides the global configuration command ip
forward-protocol to allow an
administrator to forward any UDP port in addition to the default
eight. In order to forward UDP on port 517, you would use the global
configuration command, ip
forward-protocol udp 517. This
command is used not only to add a UDP port to the "default
eight" (see Figure ), but also to subtract an unwanted service
from the default group. For instance, if you wanted to forward DHCP,
TFTP, and DNS, and, for some reason, not Time, TACACS, and NetBIOS,
the Cisco IOS requires that you configure the router according to
Figure . |