Wired Intelligent Edge (Campus Switching and Routing)

This feature is applicable from MAS switch on code 7.2 and above.

A packet, which is sent to the broadcast address of a particular subnet where the sending host is not directly attached, can be forwarded through the network as a unicast until it arrives at the destination subnet. Once the packet has arrived at the destination subnet, it will be converted into a Layer 2 broadcast packet and be flooded as normal broadcast packet. All the layer 3 devices, such as routers, along the path to the subnet, are not ware of the fact that packet is a directed broadcast
 
Usage of Directed Broadcast
 
1. Directed broadcast is utilized in an environment where “Wake-on-LAN” feature is used.
2. In an environment that has “Wake-on-LAN” enabled, a host on a separate subnet can send a specific packet to start-up or “wake” the hosts on a particular subnet
 
To  Configure from CLI
 
(ArubaS3500-48P) (config) #interface vlan  2   
(ArubaS3500-48P) (vlan "2") #ip directed-broadcast
 
ArubaS3500-48P) #show interface vlan  2
VLAN2 is administratively Up, Line protocol is Up
Hardware is CPU Interface, Address is 00:0b:86:6a:1c:c0
Description: 802.1Q VLAN
Internet address is 20.20.20.1, Netmask is 255.255.255.0
Internet address is 30.30.30.2, Netmask is 255.255.255.0 secondary
IPV6 link-local address is fe80::b:8600:26a:1cc0
Global Unicast address(es):
Routing interface is enable, Forwarding mode is enable
Directed broadcast is enable, BCMC Optimization disabled
Encapsulation 802, Loopback not set
Interface index: 50331650
MTU 1500 bytes
 
Note:- The directed broadcast feature should only be turned on when necessary. There are known security risks involving directed broadcast where malicious user can trigger denial of service (DoS) attack using this feature.