Chapter 8: IP Routing Configuration Guide

BOOTP/DHCP (port 67 and 68)

DNS (port 37)

NetBIOS Name Server (port 137)

NetBIOS Datagram Server (port 138)

TACACS Server (port 49)

Time Service (port 37)

To forward UDP broadcast packets received on interface int1 to the host 10.1.4.5 for the six default UDP services:

ssr(config)# ip helper-address interface int1 10.1.4.5

To forward UDP broadcast packets received on interface int2 to the host 10.2.48.8 for packets with the destination port 111 (port mapper):

ssr(config)# ip helper-address interface int2 10.2.48.8 111

To forward UDP broadcast packets received on interface int3 to all other interfaces:

ssr(config)# ip helper-address interface int3 all-interfaces

Configuring Direct Broadcast

Directed broadcast packets are network or subnet broadcast packets which are sent to a router to be forwarded as broadcast packets. They can be misused to create Denial Of Service attacks. The SSR protects against this possibility by not forwarding directed broadcasts, by default. To enable the forwarding of directed broadcasts, use the ip enable directed-broadcastcommand.

You can configure the SSR to forward all directed broadcast traffic from the local subnet to a specified IP address or all associated IP addresses. This is a more efficient method than defining only one local interface and remote IP address destination at a time with the ip- helper command when you are forwarding traffic from more than one interface in the local subnet to a remote destination IP address.

To enable directed broadcast forwarding on the “int4” network interface:

ssr(config)# ip enable directed-broadcast interface int4

SmartSwitch Router User Reference Manual

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Cabletron Systems 9032578-05 manual Configuring Direct Broadcast