Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual page 1371

Example: Configuring Layer 3 Subinterfaces for a Distribution Switch and an Access
Switch
Requirements
Overview and Topology
Copyright © 2010, Juniper Networks, Inc.
In a large LAN, you commonly need to partition the network into multiple VLANs. You
can configure Layer 3 subinterfaces to route traffic between the VLANs. In one common
topology, known as a "router on a stick" or a "one-armed router," you connect a router
to an access switch with connections to multiple VLANs.
This example describes how to create Layer 3 subinterfaces on trunk interfaces of a
distribution switch and access switch so that you can route traffic among multiple VLANs:
Requirements on page 1267
Overview and Topology on page 1267
Configuring the Access Switch Subinterfaces on page 1268
Configuring the Distribution Switch Subinterfaces on page 1270
Verification on page 1272
This example uses the following hardware and software components:
For the distribution switch, one EX4200-24F switch. This model is designed to be used
as a distribution switch for aggregation or collapsed core network topologies and in
space-constrained data centers. It has twenty-four 1-Gigabit Ethernet fiber SFP ports
and an EX-UM-2XFP uplink module with two 10-Gigabit Ethernet XFP ports.
For the access switch, any Layer 2 switch that supports 802.1Q VLAN tags.
Junos OS Release 9.2 or later for EX Series switches.
Before you connect the switches, make sure you have:
Connected the two switches.
Configured the necessary 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.
In a large office with multiple buildings and VLANs, you commonly aggregate traffic from
a number of access switches into a distribution switch. This configuration example shows
a simple topology to illustrate how to connect a single Layer 2 access switch connected
to multiple VLANs to a distribution switch, enabling traffic to pass between those VLANs.
In the example topology, the LAN is segmented into five VLANs, all associated with
interfaces on the access switch. One 1-Gigabit Ethernet port on the access switch's uplink
module connects to one 1-Gigabit Ethernet port on the distribution switch.
Table 186 on page 1268 lists the settings for the example topology.
Chapter 57: Examples of Interfaces Configuration
1267