ip helper-address (Global Config)

Use this command to configure the relay of certain UDP broadcast packets received on any interface. This command can be invoked multiple times, either to specify multiple server addresses for a given UDP port number or to specify multiple UDP port numbers handled by a specific server.

Default No helper addresses are configured.
Format ip helper-address server-address [dest-udp-port | dhcp | domain | isakmp | mobile-ip | nameserver | netbios-dgm | netbios-ns | ntp | pim-auto-rp | rip | tacacs | tftp | time]
  • Global Config
  • Virtual Router Config
Parameter Description
server-address The IPv4 unicast or directed broadcast address to which relayed UDP broadcast packets are sent. The server address cannot be an IP address configured on any interface of the local router.
dest-udp-port A destination UDP port number from 0 to 65535.
port-name The destination UDP port may be optionally specified by its name. Whether a port is specified by its number or its name has no effect on behavior. The names recognized are as follows:
  • dhcp (port 67)
  • domain (port 53)
  • isakmp (port 500)
  • mobile-ip (port 434)
  • nameserver (port 42)
  • 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)
  • time (port 37)

Other ports must be specified by number.

To relay DHCP (Dynamic Host Configuration Protocol) packets received on any interface to two DHCP servers, and, use the following commands:

(Extreme 220) #config
(Extreme 220) (Config) #ip helper-address dhcp
(Extreme 220) (Config) #ip helper-address dhcp

To relay UDP packets received on any interface for all default ports to the server at, use the following commands:

(Extreme 220) #config
(Extreme 220) (Config) #ip helper-address