Configuring UDP broadcast forwarding on individual VLANs

This command routes an inbound UDP broadcast packet received from a client on the VLAN to the unicast or broadcast address configured for the UDP port type.


no ip forward-protocol udp < ip-address > {< port-number | port-name >}

Used in a VLAN context to configure or remove a server or broadcast address and its associated UDP port number. You can configure a maximum of 16 forward-protocol udp assignments in a given VLAN. The switch allows a total of 256 forward-protocol udp assignments across all VLANs.

You can configure UDP broadcast forwarding addresses regardless of whether UDP broadcast forwarding is globally enabled on the switch. However, the feature does not operate unless globally enabled.

This can be either of the following:
  • The unicast address of a destination server on another subnet. For example:

  • The broadcast address of the subnet on which a destination server operates. For example, the following address directs broadcasts to All hosts in the subnet:


The subnet mask for a forwarded UDP packet is the same as the subnet mask for the VLAN (or subnet on a multinetted VLAN) on which the UDP broadcast packet was received from a client.


Any UDP port number corresponding to a UDP application supported on a device at the specified unicast address or in the subnet at the specified broadcast address.

Allows use of common names for certain well-known UDP port numbers. You can type in the specific name instead of having to recall the corresponding number:

Domain name service (53)


NetBIOS name service (137)


NetBIOS datagram service (138)


Remote authentication dial-in user service (1812)


Remote authentication dial-in user service (1645)


Routing information protocol (520)


Simple network management protocol (161)


Simple network management protocol (162)


Trivial file transfer protocol (69)


Time protocol (37)


The following command configures the routing switch to forward UDP broadcasts from a client on VLAN 1 for a time protocol server:

switch(vlan-1)# ip forward-protocol udp timep