Juniper EX3300 Hardware Guide

Understanding Unicast RPF
Unicast reverse-path forwarding (RPF) helps protect the switch against denial-of-service
(DoS) and distributed denial-of-service (DDoS) attacks by verifying the unicast source
address of each packet that arrives on an ingress interface where unicast RPF is enabled.
It also helps ensure that traffic arriving on ingress interfaces comes from a network source
that the receiving interface can reach.
When you enable unicast RPF, the switch forwards a packet only if the receiving interface
is the best return path to the packet's unicast source address. This is known as strict
mode unicast RPF.
NOTE: On Juniper Networks EX3200, EX4200, and EX4300 Ethernet
Switches, the switch applies unicast RPF globally to all interfaces when
unicast RPF is configured on any interface. For additional information, see
“Limitations of the Unicast RPF Implementation on EX3200, EX4200, and
EX4300 Switches” on page 22.
This topic covers:
•
Unicast RPF for Switches Overview on page 19
•
Unicast RPF Implementation on page 20
•
When to Enable Unicast RPF on page 20
•
When Not to Enable Unicast RPF on page 21
•
Limitations of the Unicast RPF Implementation on EX3200, EX4200, and EX4300
Switches on page 22
Unicast RPF for Switches Overview
Unicast RPF functions as an ingress filter that reduces the forwarding of IP packets that
might be spoofing an address. By default, unicast RPF is disabled on the switch interfaces.
The type of unicast RPF provided on the switches—that is, strict mode unicast RPF is
especially useful on untrusted interfaces. An untrusted interface is an interface where
untrusted users or processes can place packets on the network segment.
The switch supports only the active paths method of determining the best return path
back to a unicast source address. The active paths method looks up the best reverse
path entry in the forwarding table. It does not consider alternate routes specified using
routing-protocol-specific methods when determining the best return path.
If the forwarding table lists the receiving interface as the interface to use to forward the
packet back to its unicast source, it is the best return path interface.
Use strict mode unicast RPF only on symmetrically routed interfaces. (For information
about symmetrically routed interfaces, see “When to Enable Unicast RPF” on page 20.)
19Copyright © 2015, Juniper Networks, Inc.
Chapter 1: Interfaces Overview

Juniper EX3300 Specifications

General

Ethernet LAN	Yes
Authentication method	RADIUS, TACACS+
Connectivity technology	Wired
Ethernet interface type	Gigabit Ethernet
Number of VLANs	4096
Networking standards	IEEE 802.1ab, IEEE 802.1D, IEEE 802.1Q, IEEE 802.1s, IEEE 802.1w, IEEE 802.1x, IEEE 802.3, IEEE 802.3ab, IEEE 802.3ad, IEEE 802.3x, IEEE 802.3z
Ethernet LAN data rates	10, 100, 1000 Mbit/s
Copper ethernet cabling technology	1000BASE-T, 100BASE-TX, 10BASE-T
Console port	-
ExpressCard slot	No
Fiber ports quantity	4
USB 2.0 ports quantity	0
Basic switching RJ-45 Ethernet ports quantity	48
Throughput	130 Mpps
Number of queues	8
MAC address table	16000 entries
Maximum data transfer rate	176 Gbit/s
Supported data transfer rates	10, 100, 1000Mbps
Switch type	Managed
Switch layer	L2
Security algorithms	SSH-2
Power source	AC
AC input voltage	100 - 240 V
Power consumption (typical)	100 W
Form factor	1U
Product color	Black
Flash memory	1024 MB
Processor frequency	1000 MHz
Compatible operating systems	Junos
Operating altitude	0 - 3049 m
Non-operating altitude	0 - 4877 m
Storage temperature (T-T)	-40 - 70 °C
Operating temperature (T-T)	0 - 45 °C
Storage relative humidity (H-H)	0 - 95 %
Operating relative humidity (H-H)	10 - 85 %
Supported network protocols	IPv6

Weight and Dimensions

Depth	310 mm
Width	437 mm
Height	44 mm
Weight	4900 g