Table of Contents
Advertisement
netbios-dgm (port 138), netbios-ns (port 137), ntp (port 123), pim-auto-
rp (port 496), rip (port 520), tacacs (port 49), tftp (port 69), and time
(port 37). Other ports must be specified by number.
Default Configuration
No helper addresses are configured.
Command Mode
Global Configuration mode, Virtual Router Configuration mode
User Guidelines
This command can be invoked multiple times, either to specify multiple
server addresses for a given port number or to specify multiple port numbers
handled by a specific server. Broadcast packets other than DHCP require
configuration of a destination UDP port number for IP helper if they are not
already listed in Table 7-1. The switch is able to supply the appropriate UDP
destination port numbers by examining the DHCP message, so configuration
of a UDP destination port is not required for unicast forwarding of DHCP.
The command no ip helper-address with no arguments clears all global IP
helper addresses.
When in Virtual Router Configuration mode, this command operates within
the context of the virtual router instance. When in Global Configuration
mode, the command operates on the global router instance.
Virtual Router Configuration mode is only available on the
N3000/N3100/N4000 switches.
Example
To relay DHCP packets received on any interface to two DHCP servers,
10.1.1.1 and 10.1.2.1, use the following commands:
console#config
console(config)#ip helper-address 10.1.1.1 dhcp
console(config)#ip helper-address 10.1.2.1 dhcp
To relay UDP packets received on any interface for all default ports (see
Table 7-1) to the server at 20.1.1.1, use the following commands:
console#config
console(config)#ip helper-address 20.1.1.1
Layer 3 Routing Commands
1453
Advertisement
Table of Contents
