H3C Technologies H3C S3600 Series Switches - Manual (Page 849)

1-2
By default, with UDP Helper enabled, the device forwards broadcast packets with the six UDP
destination port numbers listed in Table 1-1 .
Table 1-1 List of default UDP ports
Protocol UDP port number
DNS (Domain Name System) 53
NetBIOS-DS (NetBIOS Datagram Service) 138
NetBIOS-NS (NetBIOS Name Service) 137
TACACS (Terminal Access Controller Access
Control System)
49
TFTP (Trivial File Transfer Protocol) 69
Time Service 37
Configuring UDP Helper
Follow these steps to configure UDP Helper:
To do… Use the command… Remarks
Enter system view system-view —
Enable UDP Helper udp-helper enable
Required
Disabled by default.
Specify a UDP port number
udp-helper port { port-number
| dns | netbios-ds | netbios-ns
| tacacs | tftp | time }
Optional
By default, the device enabled
with UDP Helper forwards the
broadcast packets containing
any of the six port numbers 53,
138, 137, 49, 69 and 37.
Enable the UDP Helper
TTL-keep function
udp-helper ttl-keep enable
Optional
Disabled by default. That is,
UDP Helper does not forward
IP broadcasts with the TTL field
being 1.
Enter VLAN interface view
interface Vlan-interface
vlan-id
—
Specify the destination server
to which the UDP packets are
to be forwarded
udp-helper server ip-address
Required
No destination server is
specified by default.