Table of Contents

1 UDP Helper Configuration Commands· 1-1

UDP Helper Configuration Commands· 1-1

display udp-helper server 1-1

reset udp-helper packet 1-1

udp-helper enable· 1-2

udp-helper port 1-3

udp-helper server 1-4

 

UDP Helper Configuration Commands

display udp-helper server

Syntax

display udp-helper server [ interface Vlan-interface vlan-id ]

View

Any view

Parameters

vlan-id: VLAN interface number.

Description

Use the display udp-helper server command to display the UDP broadcast relay forwarding information. The information includes the VLAN interface enabled with UDP Helper, IP address of the destination server, and the number of UDP packets forwarded to the destination server. If a vlan-id is specified, UDP broadcast relay forwarding information of the specified VLAN interface is displayed.

Examples

# Display the UDP broadcast relay forwarding information on VLAN-interface 1.

<Sysname> display udp-helper server interface Vlan-interface 1

 Interface name       Server address      Packets sent

 Vlan-interface1      192.1.1.2           0

The information above shows that the IP address of the destination server corresponding to VLAN-interface 1 is 192.1.1.2, and no packets have been forwarded to the destination server.

Table 1-1 Description on the fields of the display udp-helper server command

Field	Description
Interface name	Interface enabled with UDP Helper
Server address	Destination server IP address to which UDP packets are forwarded
Packets sent	Number of UDP packets forwarded to the destination server

 

reset udp-helper packet

Syntax

reset udp-helper packet

View

User view

Parameters

None

Description

Use the reset udp-helper packet command to clear UDP Helper statistics.

Examples

# Clear UDP Helper statistics.

<Sysname> reset udp-helper packet

udp-helper enable

Syntax

udp-helper enable

undo udp-helper enable

View

System view

Parameters

None

Description

Use the udp-helper enable command to enable UDP Helper function. After this function is enabled, the switch converts broadcasts containing the specified port numbers into unicasts and forwards them to the destination server.

Use the undo udp-helper enable command to disable UDP Helper function.

By default, UDP Helper is disabled.

Note that: On an S3600 Series Ethernet Switch, the reception of directed broadcast packets to a directly connected network is disabled by default. As a result, UDP Helper is available only when the ip forward-broadcast command is configured in system view. For details about the ip forward-broadcast command, refer to the IP Address and Performance part of this manual.

Examples

# Enable UDP Helper.

<Sysname> system-view

System View: return to User View with Ctrl+Z.

[Sysname] udp-helper enable

udp-helper port

Syntax

udp-helper port { port-number | dns | netbios-ds | netbios-ns | tacacs | tftp | time }

undo udp-helper port { port-number | dns | netbios-ds | netbios-ns | tacacs | tftp | time }

View

System view

Parameters

port-number: Number of the UDP port with which UDP packets are to be forwarded, in the range 0 to 65535 (except for 67 and 68).

dns: Forwards Domain Name System (DNS) data packets. The corresponding UDP port number is 53.

netbios-ds: Forwards NetBIOS data packets. The corresponding UDP port number is 138.

netbios-ns: Forwards NetBIOS name service data packets. The corresponding UDP port number is 137.

tacacs: Forwards terminal access controller access control system (TACACS) data packet. The corresponding UDP port number is 49.

tftp: Forwards Trivial File Transfer Protocol (TFTP) data packets. The corresponding UDP port number is 69.

time: Forwards time service data packets. The corresponding UDP port number is 37.

Description

Use the udp-helper port command to configure the UDP port with which broadcast packets are to be forwarded.

Use the undo udp-helper port command to remove the configuration.

By default, the UDP Helper enabled device forwards broadcast packets with any of the six UDP port numbers 53, 138, 137, 49, 69 and 37.

Note that:

l          You need to enable the UDP Helper function before specifying any UDP port; otherwise, the system prompts error information. When the UDP helper function is disabled, all configured UDP ports are disabled, including the default ports.

l          The relaying of BOOTP/DHCP broadcast packets is implemented through the DHCP relay agent function using UDP port 67 and 68. That is, the UDP port number cannot be set to 67 or 68 for UDP Helper.

l          The dns, netbios-ds, netbios-ns, tacacs, tftp, and time keywords correspond to the six default ports. You can configure the default ports by specifying port numbers or the corresponding parameters. For example, udp-helper port 53 and udp-helper port dns specify the same port.

l          When you view the configuration information by using the display current-configuration command, information about default UDP ports is not displayed. Such information is displayed only when a default port is disabled.

l          Currently, you can configure up to 256 UDP ports on the device.

Examples

# Enable forwarding of UDP broadcasts with a destination UDP port number of 100.

<Sysname> system-view

System View: return to User View with Ctrl+Z.

[Sysname] udp-helper port 100

# Disable forwarding of UDP broadcasts with a destination UDP port number of 53.

[Sysname] undo udp-helper port 53

udp-helper server

Syntax

udp-helper server ip-address

undo udp-helper server [ ip-address ]

View

VLAN interface view

Parameters

ip-address: IP address of the destination server, in dotted decimal notation.

Description

Use the udp-helper server command to specify the destination server to which the UDP packets are to be forwarded.

Use the undo udp-helper server command to remove the specified destination server.

No destination server is specified by default.

Note that:

l          Executing the undo udp-helper server command without specifying the ip-address argument removes all the destination servers configured on the current interface.

l          You can specify up to 20 destination server IP addresses on a VLAN interface.

Related commands: display udp-helper server.

Examples

# Specify the destination server at 192.1.1.2 for VLAN-interface 1.

<Sysname> system-view

System View: return to User View with Ctrl+Z.

[Sysname] interface Vlan-interface 1

[Sysname-Vlan-interface1] udp-helper server 192.1.1.2

# Remove all the specified destination servers for VLAN-interface 1.

[Sysname-Vlan-interface1] undo udp-helper server