Configuring A Layer 3 Subinterface (Cli Procedure); Configuring Unicast Rpf (Cli Procedure) - Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual

Configuring a Layer 3 Subinterface (CLI Procedure)

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Configuring Unicast RPF (CLI Procedure)

Copyright © 2010, Juniper Networks, Inc.
EX Series switches use Layer 3 subinterfaces to divide a physical interface into multiple
logical interfaces, each corresponding to a VLAN. The switch uses the Layer 3
subinterfaces to route traffic between subnets.
To configure Layer 3 subinterfaces, you enable VLAN tagging and partition one or more
physical ports into multiple logical interfaces, each corresponding to a VLAN ID.
Before you begin, make sure you set up your VLANs. See "Configuring VLANs for EX Series
Switches (CLI Procedure)" on page 1600 or "Configuring VLANs for EX Series Switches
(J-Web Procedure)" on page 1597.
To configure Layer 3 subinterfaces:
Enable VLAN tagging:
1.
[edit interfaces interface-name]
user@switch# set vlan-tagging
Bind each VLAN ID to a logical interface:
2.
[edit interfaces interface-name]
user@switch# set unit logical-unit-number vlan-id vlan-id-number
Example: Configuring Layer 3 Subinterfaces for a Distribution Switch and an Access
Switch on page 1267
Verifying That Layer 3 Subinterfaces Are Working on page 1348
Understanding Layer 3 Subinterfaces on page 1248
Unicast reverse-path forwarding (RPF) can help protect your LAN from denial-of-service
(DoS) and distributed denial-of-service (DDoS) attacks on untrusted interfaces. Enabling
unicast RPF on the switch interfaces filters traffic with source addresses that do not use
the incoming interface as the best return path back to the source. When a packet comes
into an interface, if that interface is not the best return path to the source, the switch
discards the packet. If the incoming interface is the best return path to the source, the
switch forwards the packet.
NOTE: On EX3200 and EX4200 switches, you can only enable unicast RPF
globally, on all switch interfaces. You cannot enable unicast RPF on a
per-interface basis.
Before you begin:
On an EX8200 switch, ensure that the selected switch interface is symmetrically routed
before you enable unicast RPF. A symmetrically routed interface is an interface that
Chapter 58: Configuring Interfaces
1339