Juniper Networks 10.4 Basic Layer 2 Features on MX Series Routers

CHAPTER2
Basic Layer 2 Features on MX Series
Routers
•Layer2 Features for a Bridging Environment on page21
•ExampleRoadmap: Configuring a Basic Bridge Domain Environmenton page 22
•ExampleStep: Configuring Interfacesand VLAN Tags on page 24
•ExampleStep: Configuring Bridge Domains on page 30
•ExampleStep: Configuring Spanning TreeProtocols on page 32
•ExampleStep: Configuring IntegratedBridging and Routing on page 34
Layer2 Features for a Bridging Environment
Youconfigure MX Seriesrouters exactly as you wouldany other router running the Junos
OS.That is, all the familiar Layer 3 featuresand protocols are availableon the MX Series
routers.However,you can configure Layer 2 features thatare unique to the MX Series
routers.This chapter addresses Layer2 configuration for the MX Series routers. For
informationabout configuring Layer 3 featuresand protocols, as well as comprehensive
informationaboutinterfaces and system basics,please see the other Junos configuration
guides.
ConfiguringLayer 2 features on an MX Seriesrouter can vary from the very simple
(aggregatedEthernet trunk interfaces,spanning trees), to the more complex (inner and
outerVLAN tags, broadcast domains), to the very complicated(integrated bridging and
routing,Layer 2 filtering). This chapter offersa fairly complex configuration forLayer 2
processingin a bridged environment.
Generally,there are four thingsthat you must configure in an Layer 2 environment:
•Interfacesand virtual LAN (VLAN) tags—Layer 2 interfacesare usually various type of
Ethernetlinks with VLAN tags used to connect to customerdevices or other bridges
orrouters.
•Bridgedomains—Bridge domains limit the scope of media access control (MAC)
learning(and thereby the size of the MAC table)and also determine where the device
shouldpropagate frames sent tobroadcast, unknown unicast, and multicast (BUM)
MACaddresses.
21Copyright© 2010, Juniper Networks,Inc.