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- Table of Contents
-
- H3C S5500-SI Series Ethernet Switches Operation Manual-Release 1205-(V1.03)
- 00-1Cover
- 00-2Overview
- 01-Login Operation
- 02-Basic System Configuration and Maintenance Operation
- 03-File System Management Operation
- 04-VLAN Operation
- 05-QinQ-BPDU TUNNEL Operation
- 06-Port Correlation Configuration Operation
- 07-MAC Address Table Management Operation
- 08-MSTP Operation
- 09-IP Address and Performance Operation
- 10-IPv6 Configuration Operation
- 11-Routing Overview Operation
- 12-IPV4 Routing Operation
- 13-IPv6 Routing Operation
- 14-802.1x-HABP-MAC Authentication Operation
- 15-AAA-RADIUS-HWTACACS Operation
- 16-Multicast Protocol Operation
- 17-ARP Operation
- 18-DHCP Operation
- 19-ACL Operation
- 20-QoS Operation
- 21-Port Mirroring Operation
- 22-Cluster Operation
- 23-SNMP-RMON Operation
- 24-NTP Operation
- 25-DNS Operation
- 26-Information Center Operation
- 27-NQA Operation
- 28-SSH Terminal Service Operation
- 29-UDP Helper Operation
- 30-SSL-HTTPS Operation
- 31-PKI Operation
- 32-PoE-PoE Profile Operation
- 33-Appendix
- Related Documents
-
| Title | Size | Download |
|---|---|---|
| 29-UDP Helper Operation | 56 KB |
Table of Contents
Chapter 1 UDP Helper Configuration
1.1 Introduction to UDP Helper
1.3 Displaying and Maintaining UDP Helper
1.4 UDP Helper Configuration Example
Chapter 1 UDP Helper Configuration
When configuring UDP Helper, go to these sections for information you are interested in:
l Displaying and Maintaining UDP Helper
l UDP Helper Configuration Example
& Note:
l By default, S5500-SI series Ethernet switches do not forward IP broadcast packets. So, to utilize the UDP Helper function, you need to execute the ip forward-broadcast command in system view first. For details, refer to the IP Address and Performance part of the manual.
l Currently, interface-related configurations concerning the UDP Helper function can only be performed on VLAN interfaces.
1.1 Introduction to UDP Helper
UDP Helper makes the device to function as a relay that converts UDP broadcast packets into unicast packets and forwards them to a specified server.
With UDP Helper enabled, the device decides whether to forward a received UDP broadcast packet according to the UDP port number of the packet. If the packet needs to be forwarded, the device modifies the destination IP address in the IP header and then sends the packet to the specified destination server. Otherwise, the device passes the packet to the upper layer for the packet to be processed.
With UDP Helper enabled, the device relays broadcast packets of six default UDP ports by default. The default UDP ports are listed in Table 1-1.
Table 1-1 List of default UDP ports
|
Protocol |
UDP port number |
|
TFTP (trivial file transfer protocol) |
69 |
|
DNS (domain name system) |
53 |
|
Time service |
37 |
|
NetBIOS-NS (NetBIOS name service) |
137 |
|
NetBIOS-DS (NetBIOS datagram service) |
138 |
|
TACACS (terminal access controller access control system) |
49 |
1.2 Configuring UDP Helper
Table 1-2 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 |
udp-helper port { port-number | dns | netbios-ds | netbios-ns | tacacs | tftp | time } |
Optional By default, the UDP helper enabled device converts and forwards broadcast packets of ports 69, 53, 37, 137, 138, and 49. |
|
Enter VLAN interface view |
interface interface-type interface-number |
— |
|
Configure the destination server to which the UDP broadcast packets are to be forwarded |
udp-helper server ip-address |
Required No destination server is configured by default. |
Caution:
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, the UDP Helper configuration on default UDP ports is not displayed. The UDP Helper configuration of a default UDP port is displayed only when UDP Helper is disabled on the port.
l The configuration of all UDP ports (including the default ports) is removed if you disabled UDP Helper.
l You can configure up to 256 UDP ports that require relaying and forwarding.
l You can configure up to 20 destination servers at an interface.
l If the destination server is configured on a VLAN interface, the broadcast packets from a VLAN port to a specific UDP port will be unicast to the destination server configured on that VLAN interface after UDP Helper is enabled.
1.3 Displaying and Maintaining UDP Helper
Table 1-3 Displaying and maintaining UDP Helper
|
To do… |
Use the command… |
Remarks |
|
Display the information of the destination server and the number of packets forwarded by UDP relay |
display udp-helper server [ interface interface-type interface-number ] |
Available in any view |
|
Clear statistics about packets forwarded by UDP relay |
reset udp-helper packet |
Available in user view |
1.4 UDP Helper Configuration Example
I. Network requirements
The VLAN interface of a device has an IP address of 10.110.1.1/16, connecting to network segment 10.110.0.0/16. Specify to forward broadcast packets with destination UDP port 55 to destination server 202.38.1.2/24.
II. Network diagram
Figure 1-1 Network diagram for UDP Helper configuration
III. Configuration procedure
& Note:
The following configuration assumes that the route between the device and the network segment 202.38.0.0/24 is reachable.
# Enable UDP Helper.
<Sysname> system-view
[Sysname] udp-helper enable
# Specify to forward the broadcast packets with destination UDP port being 55.
[Sysname] udp-helper port 55
# Specify the server with the IP address of 202.38.1.2 as the destination server to which UDP broadcast packets are to be forwarded.
[Sysname] interface Vlan-interface 1
[Sysname-Vlan-interface1] ip address 10.110.1.1 16
[Sysname-Vlan-interface1] udp-helper server 202.38.1.2
