Configuring Bridged Ip; Overview; Proxy Arp; Chapter 13 Configuring Bridged Ip - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - LINK LAYER CONFIGURATION GUIDE 2010-10-13 Configuration Manual

CHAPTER 13

Configuring Bridged IP

Overview

Proxy ARP

Copyright © 2010, Juniper Networks, Inc.
E Series routers support bridged IP (1483) interfaces.
This chapter contains the following sections:
Overview on page 437
Platform Considerations on page 438
References on page 439
Before You Configure Bridged IP on page 439
Configuring Bridged IP on page 440
You can configure a bridged IP interface to manage IP packets that are encapsulated
inside an Ethernet frame running over a permanent virtual circuit (PVC).
When you configure a bridged IP interface, it automatically performs proxy Address
Resolution Protocol (ARP). You can also configure the router as a relay agent that
forwards Dynamic Host Configuration Protocol (DHCP) broadcasts.
Proxy ARP allows your router to respond to ARP requests on behalf of an Ethernet end
node.
The router performs proxy ARP for the ARP requests that come in over the bridged IP
interface when both of the following conditions are met:
The IP address in the ARP request matches an entry in the routing table.
The route is on a different interface than the one on which the router received the ARP
request.
If you specify that the bridged IP interface performs unrestricted proxy ARP, it also
performs proxy ARP when the route is on the interface that received the ARP request.
In most situations, do not configure the router to perform unrestricted proxy ARP. Do so
for special situations, such as when cable modems are used. When an IP client broadcasts
the ARP request across the Ethernet wire, the end node with the correct IP address
responds to the ARP request and provides the correct MAC address. If the unrestricted
437