Login
- Table of Contents
-
- H3C S3600 Series Ethernet Switches Operation Manual-Release 1510(V1.04)
- 00-1Cover
- 00-2Product Overview
- 01-CLI Operation
- 02-Login Operation
- 03-Configuration File Management Operation
- 04-VLAN Operation
- 05-IP Address and Performance Configuration Operation
- 06-Management VLAN Operation
- 07-Voice VLAN Operation
- 08-GVRP Operation
- 09-Port Basic Configuration Operation
- 10-Link Aggregation Operation
- 11-Port Isolation Operation
- 12-Port Security-Port Binding Operation
- 13-DLDP Operation
- 14-MAC Address Table Operation
- 15-Auto Detect Operation
- 16-MSTP Operation
- 17-Routing Protocol Operation
- 18-Multicast Operation
- 19-802.1x Operation
- 20-AAA-RADIUS-HWTACACS-EAD Operation
- 21-VRRP Operation
- 22-Centralized MAC Address Authentication Operation
- 23-ARP Operation
- 24-DHCP Operation
- 25-ACL Operation
- 26-QoS-QoS Profile Operation
- 27-Web Cache Redirection Operation
- 28-Mirroring Operation
- 29-IRF Fabric Operation
- 30-Cluster Operation
- 31-PoE-PoE Profile Operation
- 32-UDP Helper Operation
- 33-SNMP-RMON Operation
- 34-NTP Operation
- 35-SSH Terminal Service Operation
- 36-File System Management Operation
- 37-FTP and TFTP Operation
- 38-Information Center Operation
- 39-System Maintenance and Debugging Operation
- 40-VLAN-VPN Operation
- 41-HWPing Operation
- 42-DNS Operation
- 43-Access Management Operation
- 44-Appendix
- Related Documents
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| Title | Size | Download |
|---|---|---|
| 32-UDP Helper Operation | 81 KB |
Table of Contents
Chapter 1 UDP Helper Configuration
1.1 Introduction to UDP Helper
1.3 Displaying and Maintaining UDP Helper
Chapter 1 UDP Helper Configuration
1.1 Introduction to UDP Helper
UDP Helper is to relay specified UDP packets. In other words, UDP Helper functions 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 sends the packet to its upper layer.
& Note:
Relay forwarding of BOOTP/DHCP broadcast packets is implemented by the DHCP relay module using UDP ports 67 and 68, so these two ports cannot be configured as UDP-Helper relay port.
Table 1-1 lists the default UDP ports that are commonly used to forward broadcast packets in UDP Helper function. With UDP Helper enabled, the system unicasts the broadcast packets of those default UDP ports to a specified destination server. You can also specify other UDP ports to relay broadcast packets.
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 |
1.2 Configuring UDP Helper
Table 1-2 Configure UDP Helper
|
Operation |
Command |
Description |
|
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 To use the default UDP ports for relay forwarding, this command can be ignored, otherwise, use this command to perform configuration as required. After UDP-Helper is enabled, the broadcast packets through ports 53, 138, 137, 49, 69 and 37 are relayed by default. |
|
Enter VLAN interface view |
interface Vlan-interface vlan-id |
— |
|
Configure the destination server to which the UDP packets are to be forwarded |
udp-helper server ip-address |
Required No destination server is configured by default. |
Note that:
l You need to enable the UDP Helper function before specifying any UDP port to relay UDP broadcast packets; otherwise, the configuration fails.
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 With the UDP Helper function enabled, the six default ports are specified to be UDP ports to relay UDP broadcast packets, no further configuration is need.
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 When the UDP helper function is disabled, all configured UDP ports are disabled, including the default ports.
l A UDP helper enabled device can have up to 256 UDP port for packet relay.
l A VLAN interface corresponds to a maximum of 20 destination servers.
l If the destination server is configured on a VLAN interface, the broadcast packets from a VLAN interface 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
After performing the above configurations, use the display command in any view to display the running status of the UDP Helper configuration, and verify the configuration result. You can use the reset command in user view to clear statistics about packets forwarded by UDP Helper.
Table 1-3 Display and maintain UDP Helper configuration
|
Operation |
Command |
Description |
|
Display the information of the destination server and the number of packets forwarded to the destination server |
display udp-helper server [ interface Vlan-interface vlan-id ] |
You can use the display command in any view |
|
Clear statistics about packets forwarded by UDP Helper |
reset udp-helper packet |
You can use the reset command in user view |
1.4 Configuration Example
1.4.1 Network requirements
PC1 resides on network segment 192.168.1.1/24 and PC2 on 10.2.72.1/24; they are connected by two switches and are routable to each other. It is required to configure UDP Helper on the switch, letting PC1 to search for PC2. (Broadcast packets through port 137 are used for searching.)
1.4.2 Network diagram
Figure 1-1 Network diagram for UDP Helper configuration
1.4.3 Configuration procedure
# Enable UDP Helper on Switch1.
<H3C> system-view
[H3C] udp-helper enable
# Specify port 137 to be the UDP port for forwarding UDP broadcast packets. Port 137 is the default UDP port, as prompted in the command line.
[H3C] udp-helper port 137
Port has been configured. Please check the port again.
# Specify the destination server to which UDP packets are to be forwarded.
[H3C] interface Vlan-interface 20
[H3C-Vlan-interface20] udp-helper server 10.2.72.1
