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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-06
Chapter 35 Configuring IP Unicast Routing
Configuring IP Addressing
Beginning in privileged EXEC mode, follow these steps to enable forwarding of IP-directed broadcasts
on an interface:
Use the no ip directed-broadcast interface configuration command to disable translation of directed
broadcast to physical broadcasts. Use the no ip forward-protocol global configuration command to
remove a protocol or port.
Forwarding UDP Broadcast Packets and Protocols
User Datagram Protocol (UDP) is an IP host-to-host layer protocol, as is TCP. UDP provides a
low-overhead, connectionless session between two end systems and does not provide for
acknowledgment of received datagrams. Network hosts occasionally use UDP broadcasts to find
address, configuration, and name information. If such a host is on a network segment that does not
include a server, UDP broadcasts are normally not forwarded. You can remedy this situation by
configuring an interface on a router to forward certain classes of broadcasts to a helper address. You can
use more than one helper address per interface.
You can specify a UDP destination port to control which UDP services are forwarded. You can specify
multiple UDP protocols. You can also specify the Network Disk (ND) protocol, which is used by older
diskless Sun workstations and the network security protocol SDNS.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Enter interface configuration mode, and specify the interface to
configure.
Step 3 no shutdown Enable the interface if necessary. By default, UNIs and ENIs are
disabled and NNIs are enabled.
Step 4 ip directed-broadcast [access-list-number]Enable directed broadcast-to-physical broadcast translation on the
interface. You can include an access list to control which broadcasts
are forwarded. When an access list is specified, only IP packets
permitted by the access list are eligible to be translated.
Step 5 exit Return to global configuration mode.
Step 6 ip forward-protocol {udp [port] | nd | sdns}Specify which protocols and ports the router forwards when
forwarding broadcast packets.
• udp—Forward UPD datagrams.
port: (Optional) Destination port that controls which UDP
services are forwarded.
• nd—Forward ND datagrams.
• sdns—Forward SDNS datagrams
Step 7 end Return to privileged EXEC mode.
Step 8 show ip interface [interface-id]
or
show running-config
Verify the configuration on the interface or all interfaces.
Step 9 copy running-config startup-config (Optional) Save your entries in the configuration file.