Chapter 11 Configuring Packet Forwarding Options - Juniper EX3400 Features Manual

CHAPTER 11
Configuring Packet Forwarding Options
Configuring Port-based LAN Broadcast Packet Forwarding
Copyright © 2017, Juniper Networks, Inc.
Configuring Port-based LAN Broadcast Packet Forwarding on page 133
You can enable a router or switch to forward LAN broadcast traffic on custom UDP ports
to specified servers by configuring port helpers with the
port configuration statement. Port helpers are also referred to as port forwarding or UDP
broadcast packet forwarding services. When you configure a port helper, the router or
switch listens for incoming UDP traffic for the configured port with destination Layer 2
MAC and Layer 3 IP broadcast addresses, and forwards the packets as unicast traffic to
a configured server.
Port helpers forward the traffic for configured ports transparently, without considering
the application layer protocols in the packets being forwarded. However, you cannot
configure a port helper to forward traffic for standard ports used by services such as
BOOTP, DNS and TFTP. These services have their own explicit packet forwarding helper
configuration options (see
You can configure port helpers to listen for and forward broadcast traffic for a configured
port using any of the following scopes:
Global scope—Forward incoming broadcast traffic on the port to a configured
destination server IP address.
Configure a global port helper using only the
specifying a particular interface. The port helper listens for incoming traffic on any
interfaces to forward to the configured server. For example:
set forwarding-options helpers port 1300 server 10.20.30.40
VLAN-specific scope—Forward incoming broadcast traffic on the port from a configured
VLAN to a configured destination server IP address.
Configure a VLAN-specific port helper using the
interface name for a VLAN, and the
incoming traffic from interfaces in the VLAN to forward to the configured server. For
example:
set forwarding-options helpers port 1064 interface irb.100 server 192.0.2.50
helpers and Configuring DNS and TFTP Packet Forwarding).
server
interface
statement. The port helper listens for
server
[edit forwarding-options helpers]
configuration option, without
statement with an IRB
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