[
Contents]
[
Prev]
[
Next]
[
Index]
[
Report an Error]
VPLS Overview
VPLS is an Ethernet-based point-to-multipoint Layer 2 VPN. It
allows you to connect geographically dispersed Ethernet LAN sites
to each other across an MPLS backbone. For customers who implement
VPLS, all sites appear to be in the same Ethernet LAN even though
traffic travels across the service provider's network.
VPLS, in its implementation and configuration, has much in common
with a Layer 2 VPN. In a VPLS topology, a packet originating within
a customer’s network is sent first to a customer edge (CE) device
(for example, a router or Ethernet switch). It is then sent to a provider
edge (PE) router within the service provider’s network. The
packet traverses the service provider’s network over an MPLS
label-switched path (LSP). It arrives at the egress PE router, which
then forwards the traffic to the CE device at the destination customer
site.
The difference is that for VPLS, packets can traverse the service
provider’s network in point-to-multipoint fashion, meaning that
a packet originating from a CE device can be broadcast to all the
PE routers participating in a VPLS routing instance. In contrast,
a Layer 2 VPN forwards packets in point-to-point fashion only. The
paths carrying VPLS traffic between each PE router participating in
a routing instance are signaled using BGP.
This topic covers:
Supported Devices and Interfaces
VPLS allows a J-series or SRX-series device to act as a PE router.
Besides configuring a VPLS routing instance on a J-series or SRX-series
device, you must also configure the interfaces that will carry VPLS
traffic between the PE router and CE devices. VPLS traffic to CE devices
are supported on the following J-series devices, SRX-series devices,
and PIMs:
- Built-in Ethernet ports on front panel
- Gigabit Ethernet uPIMs
- Gigabit Ethernet ePIMs
- Fast Ethernet PIMs
- Fast Ethernet ePIMs
 |
Note:
Ports on uPIMs and ePIMs must be in routing mode before you
can configure the corresponding interfaces for VPLS.
|
VPLS Terms
Before configuring VPLS, become familiar with the terms defined
in Table 215.
Table 215: VPLS Terms
Term
|
Definition
|
Customer edge (CE) devices
|
Routers or switches located at the customer site that connect
to the provider’s network. CE devices are typically IP routers,
but could also be an Asynchronous Transfer Mode (ATM), Frame Relay,
or Ethernet switch.
|
Class of service (CoS)
|
Method of classifying traffic on a packet-by-packet basis using
information in the type-of-service (ToS) byte to provide different
service levels to different traffic.
|
Label switched path (LSP)
|
Sequence of routers that cooperatively perform MPLS operations
for a packet stream. The first router in an LSP is called the ingress router and the last router in the path is called
the egress router. An LSP is a point-to-point,
half-duplex connection from the ingress router to the egress router.
(The ingress and egress routers cannot be the same router.)
|
Media access control
|
In the OSI seven-layer networking model defined by the IEEE,
MAC is the lower sublayer of the data link layer. The MAC sublayer
governs protocol access to the physical network medium. By using the
MAC addresses that are assigned to all ports on a router, multiple
devices on the same physical link can uniquely identify one another
at the data link layer.
|
Multiprotocol Label Switching (MPLS)
|
Mechanism for engineering network traffic patterns that functions
by assigning to network packets short labels that describe how to
forward them through the network. Also called label switching.
|
Point-to-multipoint LSP
|
RSVP-signaled LSP with a single source and multiple destinations.
|
Provider edge (PE) router
|
A router in the service provider’s network that is connected
to a customer edge (CE) device and participates in a virtual private
network (VPN or VPLS).
|
Quality of service (QoS)
|
Performance, such as transmission rates and error rates, of
a communications channel or system.
|
Virtual private LAN service (VPLS)
|
An Ethernet-based multipoint-to-multipoint Layer 2 VPN service
used for interconnecting multiple Ethernet LANs across an MPLS backbone.
VPLS is specified in IETF RFC 4761, Virtual Private LAN
Service (VPLS) Using BGP for Auto-Discovery and Signaling.
|
Related Topics
[
Contents]
[
Prev]
[
Next]
[
Index]
[
Report an Error]