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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 35 Configuring IP Unicast Routing
Configuring IP Addressing
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 that 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 configure 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.
By default, both UDP and ND forwarding are enabled if a helper address has been defined for an
interface. The description for the
ip forward-protocol
interface configuration command in the
Cisco
IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2
lists the ports that
are forwarded by default if you do not specify any UDP ports.
If you do not specify any UDP ports when you configure the forwarding of UDP broadcasts, you are
configuring the router to act as a BOOTP forwarding agent. BOOTP packets carry DHCP information.
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.
Command
Purpose
Содержание ME 3400 Series
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