Directed Broadcast Forwarding; Netbios Rebroadcast - Avaya G250 Administration

Configuring the router

Directed broadcast forwarding

A directed broadcast is an IP packet whose destination address is the broadcast address of a
network or subnet. A directed broadcast causes every host on the network to respond. You can
use directed broadcasts to obtain a list of all active hosts on the network. A hostile user can
exploit directed broadcasts to launch a denial-of-service attack on the network. For each
interface on the Avaya G250/G350 Media Gateway, you can configure whether the G250/G350
forwards directed broadcast packets to the network address or subnet mask address of the
interface.
Use the ip directed-broadcast command to enable directed broadcast forwarding on an
interface. Use the no form of this command to disable directed broadcast forwarding on an
interface.

NetBIOS rebroadcast

Network Basic Input Output System (NetBIOS) is a protocol for sharing resources among
desktop computers on a LAN. You can configure the Avaya G250/G350 Media Gateway to relay
NetBIOS UDP broadcast packets. This feature is used for applications such as WINS that use
broadcast but might need to communicate with stations on other subnetworks or VLANs.
Configuration is performed on a per-interface basis. A NetBIOS broadcast packet arrives from
an interface on which NetBIOS rebroadcast is enabled. The packet is distributed to all other
interfaces configured to rebroadcast NetBIOS.
If the NetBIOS packet is a net-directed broadcast, for example, 149.49.255.255, the packet is
relayed to all other interfaces on the list, and the IP destination of the packet is replaced by the
appropriate interface broadcast address.
If the NetBIOS broadcast packet is a limited broadcast, for example, 255.255.255.255, it is
relayed to all VLANs on which there are NetBIOS-enabled interfaces. In that case, the
destination IP address remains the limited broadcast address.
Use the ip netbios-rebroadcast both command to enable NetBIOS rebroadcasts on an
interface. Use the ip netbios-rebroadcast disable command to disable NetBIOS
rebroadcasts on an interface.
340 Administration for the Avaya G250 and Avaya G350 Media Gateways