ip forward-protocol

Use this command to enable UDP broadcast forwarding and specify which protocols will be forwarded.


ip forward-protocol {udp [port | startport endport]}
no ip forward-protocol {udp [port | startport endport]}


udp Specifies UDP as the IP forwarding protocol.
port | startport endport (Optional) Specifies a destination port or range of destination ports that control which UDP services are forwarded. If not specified, the forwarding protocols are forwarded on the default ports.

The following keywords can be used in place of the standard default port value as specified in the keyword description:

  • bootps - Specifies the Bootstrap Protocol server (67) port.
  • domain - Specifies the Domain Name Service (53) port.
  • nameserver - Specifies the IEN116 name service (42) port.
  • netbios-dgm - Specifies the NetBIOS datagram service (138) port.
  • netbios-ns - Specifies the NetBIOS name service (137) port.
  • tacacs - Specifies the Terminal Access Controller Access Control System (49) port.
  • tftp - Specifies the Trivial File Transfer Protocol (69) port.
  • time - Specifies the Time (37) port.


If port is not specified, default forwarding services will be performed as listed above.


Configuration command, Global configuration.


If a certain service exists inside the node, and there is no need to forward the request to remote networks, the “no” form of this command should be used to disable the forwarding for the specific port. Such requests will not be automatically blocked from being forwarded just because a service for them exists in the node.

The “no” form of this command removes a UDP port or protocol, disabling forwarding.


This example shows how to enable forwarding of Domain Naming System UDP datagrams (port 53):

System(rw-config)->ip forward-protocol udp 53

This example shows how to enable forwarding of Domain Naming System UDP datagrams (port 53) by naming the protocol:

System(rw-config)->ip forward-protocol udp domain