3Com 5500G, 4210 manual UDP Helper Configuration Guide, Processing, # Enable UDP Helper on Switch a

29

UDP HELPER CONFIGURATION GUIDE

UDP Helper	The Switch 5500 provides the UDP Helper function to relay specified UDP packets.
Configuration Guide	In other words, UDP Helper functions as a relay agent that converts UDP broadcast
	packets into unicast packets and forwards them to a specified destination server.
	With UDP Helper enabled, the device decides whether to forward a received UDP
	broadcast packet according to the UDP destination port number of the packet.
	■ If the destination port number of the packet matches a pre-configured port
	number on the device, the device modifies the destination IP address in the IP
	header and then sends the packet to the specified destination server.
	■ Otherwise, the device sends the packet to the upper layer protocol for
	processing.

Network Diagram Figure 79 Network diagram for UDP Helper

Vlan-int1 Vlan-int2

192.168.1.1/24 192.168.10.1/24

Switch A

PC A

192.168.1.2/24

PC B

192.168.10.2/24

Networking and PC A resides on network segment 192.168.1.0/24 and PC B on 192.168.10.0/24; Configuration they are connected through Switch A and are reachable to each other.

Requirements

It is required to configure UDP Helper on the switch, so that PC A can find PC B through computer search (Computer search uses broadcasts with the destination UDP port 137).

Applicable Products

Product series	Software version	Hardware version
Switch 5500	Release V03.02.04	All versions
Switch 5500G	Release V03.02.04	All versions
Switch 4500	Release V03.03.00	All versions

Configuration Procedure # Enable Switch A to receive directed broadcasts to a directly connected network.

[SwitchA] ip forward-broadcast

# Enable UDP Helper on Switch A.