Cisco Directed UDP Broadcast Custom Port

Last Updated: 6/22/15

Basically you just have to enabled directed broadcasts for the destination VLAN network, then set the ip helper address of the source vlan to the broadcast address of the destination VLAN (x.x.x.255), then finally adjust the global switch setting for the TCP/UDP ports that are included in the ip-helper command.

Cisco Switch config Example:

ip forward-protocol udp 6112

Int vlan 200 <--------------------------- servers
ip address 192.168.200.1 255.255.255.0
ip helper-address 192.168.10.255

Int vlan 10 <-------------- dispatch
ip address 192.168.10.1 255.255.255.0
ip directed-broadcast

full details here:

IP Application Services Configuration Guide, Cisco IOS Release 12.4 - Configuring IPv4 Broadcast Packet Handling [Cisco IOS Software Releases 12.4 Mainline] - Cisco Systems
http://www.cisco.com/en/US/docs/ios-xml/ios/ipapp/configuration/12-4/iap-bph.html

**Note on Security and Optimization: You can include an ACL with the directed broadcast command.

visit the link and view the section: "Enabling IP Directed Broadcasts with an Access List"

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