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PowerConnect B-Series FCX Configuration Guide 837
53-1002266-01
Configuring IP parameters – Layer 3 Switches
26
• Configure a helper adders on the interface connected to the clients. Specify the helper
address to be the IP address of the application server or the subnet directed broadcast
address for the IP subnet the server is in. A helper address is associated with a specific
interface and applies only to client requests received on that interface. The Layer 3 Switch
forwards client requests for any of the application ports the Layer 3 Switch is enabled to
forward to the helper address.
Forwarding support for the following application ports is enabled by default:
• bootps (port 67)
• dns (port 53)
• tftp (port 69)
• time (port 37)
• netbios-ns (port 137)
• netbios-dgm (port 138)
• tacacs (port 65)
NOTE
The application names are the names for these applications that the Layer 3 Switch software
recognizes, and might not match the names for these applications on some third-party devices. The
numbers listed in parentheses are the UDP port numbers for the applications. The numbers come
from RFC 1340.
NOTE
Forwarding support for BootP/DHCP is enabled by default. If you are configuring the Layer 3 Switch
to forward BootP/DHCP requests, refer to “Configuring BootP/DHCP relay parameters” on page 839.
You can enable forwarding for other applications by specifying the application port number.
You also can disable forwarding for an application.
NOTE
If you disable forwarding for a UDP application, forwarding of client requests received as broadcasts
to helper addresses is disabled. Disabling forwarding of an application does not disable other
support for the application. For example, if you disable forwarding of Telnet requests to helper
addresses, other Telnet support on the Layer 3 Switch is not also disabled.
Enabling forwarding for a UDP application
If you want the Layer 3 Switch to forward client requests for UDP applications that the Layer 3
Switch does not forward by default, you can enable forwarding support for the port. To enable
forwarding support for a UDP application, use the following method. You also can disable
forwarding for an application using this method.
NOTE
You also must configure a helper address on the interface that is connected to the clients for the
application. The Layer 3 Switch cannot forward the requests unless you configure the helper
address. Refer to “Configuring an IP helper address” on page 840.
To enable the forwarding of SNMP trap broadcasts, enter the following command.
PowerConnect(config)# ip forward-protocol udp snmp-trap