Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010, Configuration Manual

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Chapter 5
Configuring VLAN and S-VLAN
Subinterfaces
This chapter describes how to configure VLAN and S-VLAN subinterfaces on E Series
routers.
This chapter contains the following sections:
■
VLAN Overview on page 169
■
S-VLAN Overview on page 170
■
VLAN and S-VLAN Platform Considerations on page 171
■
VLAN and S-VLAN References on page 172
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Creating a VLAN Subinterface on page 172
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Configuring an S-VLAN Subinterface on page 180
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Configuring S-VLAN Tunnels for Layer 2 Services over MPLS on page 184
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S-VLAN Oversubscription on page 188
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Monitoring VLAN and S-VLAN Subinterfaces on page 188
VLAN Overview
A virtual LAN (VLAN) enables multiplexing multiple IP and PPPoE interfaces and
MPLS interfaces over a single physical Ethernet port. This multiplexing is accomplished
through VLAN subinterfaces. Ethernet interfaces support the 802.1q-1998 IEEE
Standards for Local and Metropolitan Area Networks: Virtual Bridged Local Area
Networks, which the router uses as its standardized format for frame tagging.
The Ethernet V2 frame format enables multiplexing of different protocols over a
single physical link. IEEE 802.1q compatibility extends the frame format by adding
a tag that contains a VLAN ID. This feature enables multiplexing of different channels
(VLANs) over the physical link; each channel is able to multiplex different protocols.
This capability works very much like ATM encapsulation as described in RFC
2684—Multiprotocol Encapsulation over ATM Adaptation Layer 5 (September 1999).
This encapsulation type enables multiplexing of multiple protocols over a single ATM
virtual circuit (VC).
As shown in Figure 13 on page 170, VLANs are similar to ATM VCs, with the VLAN
ID serving the same function as the virtual path identifier (VPI) and virtual channel
VLAN Overview
■ 169