Specifications

ip helper-address
276 SSR Command Line Interface Reference Manual
ip helper-address
Purpose
Configure the router to forward specific UDP broadcast packets across interfaces.
Format
ip helper-address interface <interface-name> <helper-address>|all-interfaces [<udp-port#>]
Mode
Configure
Description
The ip helper-address command allows the user to forward specific UDP broadcast from
one interface to another. Typically, broadcast packets from one interface are not forwarded
(routed) to another interface. However, some applications use UDP broadcast to detect the
availability of a service. Other services, for example BOOTP/DHCP require broadcast
packets to be routed so that they can provide services to clients on another subnet. An IP
helper can be configured on each interface to have UDP broadcast packets forwarded to a
specific host for a specific service or forwarded to all other interfaces.
The ip helper-address command allows the user to specify a UDP port number for which
UDP broadcast packets with that destination port number will be forwarded. By default,
if no UDP port number is specified, the SSR will forward UDP broadcast packets for the
following six services:
• BOOTP/DHCP (port 67 and 68)
• DNS (port 37)
• NetBIOS Name Server (port 137)
• NetBIOS Datagram Server (port 138)
• TACACS Server (port 49)
• Time Service (port 37)