Udp Helper Configuration; Overview Of Udp Helper - 3Com 5500-SI Configuration Manual

UDP Helper
Configuration

Overview of UDP Helper

UDP Helper
Configuration
To delete this feature, enter:
<SW5500>system-view
[SW5500]acl number 2500
[SW5500-acl-basic-2500]undo rule 0
This section contains UDP Helper configuration information.
The major function of the UDP Helper is to relay-forward UDP broadcast packets, that
is, it can convert UDP broadcast packets into unicast packets and send them to the
designated server, as a relay.
When UDP Helper starts, the Switch can judge whether to forward the UDP broadcast
packets received at the port based on UDP port ID. If yes, the Switch then modifies
the IP address in the IP packet header and sends the packet to the designated
destination server. Otherwise, it sends the packet to the upper layer module for
further processing. For the BOOTP/DHCP broadcast packet, if the client specifies in
the request message that the response message needs to be received as broadcast
packet, then the Switch broadcasts the response message to the client. Otherwise, it
unicasts the response message.
UDP Helper configuration includes:
Enabling/Disabling UDP Helper Function
■
Configuring UDP Port with Replay Function
■
Configuring the Relay Destination Server for Broadcast Packet
■
Enabling/Disabling UDP Helper Function
When the UDP Helper function is enabled, you can configure the UDP ports where
UDP function is required and the relay function is enabled at UDP ports 69, 53, 37,
137, 138, and 49. When the function is disabled, the relay function configured at all
UDP ports, including the default six ports, is disabled.
Perform the following configuration in System View.
Table 299 Enabling/Disabling UDP Helper function
Operation
Enable UDP Helper function
Disable UDP Helper function
By default, the UDP Helper function is disabled.
Configuring UDP Port with Replay Function
When the UDP relay function is enabled, by default the system forwards the
broadcast packets on the UDP ports listed in Table 300. You can configure up to 256
UDP ports with the relay function.
Table 300 Default UDP Ports List
Protocol
Trivial File Transfer Protocol (TFTP)
Domain Name System (DNS)
Time service

UDP Helper Configuration 303

Command
udp-helper enable
undo udp-helper enable
UDP port ID
69
53
37