Juniper JUNOSE, Руководство по настройке

Страница: 675 / 738

Chapter 12
VPWS Overview
This chapter describes virtual private wire service (VPWS) L2VPNs, and contains the
following sections:
■
VPWS Overview on page 639
■
BGP Signaling for L2VPNs on page 641
■
VPWS Components on page 642
■
VPWS and BGP/MPLS VPNs on page 643
■
BGP Multihoming for VPWS on page 644
■
VPWS Supported Features on page 649
■
VPWS Platform Considerations on page 649
■
VPWS References on page 650
VPWS Overview
VPWS L2VPNs employ layer 2 services over MPLS to build a topology of point-to-point
connections that connect end customer sites in a VPN. These L2VPNs provide an
alternative to private networks that have been provisioned by means of dedicated
leased lines or by means of layer 2 virtual circuits that employ ATM or Frame Relay.
The service provisioned with these L2VPNs is known as Virtual Private Wire Service
(VPWS). VPWS L2VPNs are sometimes called
Kompella L2VPNs. You configure a
VPWS instance on each associated edge router for each VPWS L2VPN.
Traditional VPNs over layer 2 circuits require the provisioning and maintenance of
separate networks for IP and for VPN services. In contrast, VPWS enables the sharing
of a provider’s core network infrastructure between IP and L2VPN services, reducing
the cost of providing those services.
VPWS also uses BGP as the signaling protocol, and consequently has a simpler design
and requires less provisioning overhead than traditional VPNs over layer 2 circuits.
BGP signaling also enables autodiscovery of L2VPN peers. VPWS is similar to
BGP/MPLS VPNs and VPLS in many respects, because all three types of services
employ BGP for signaling.
VPWS creates pseudowires that emulate layer 2 circuits. A virtual private LAN service
(VPLS) network is similar to VPWS, but provides point-to-multipoint traffic forwarding
in contrast to the VPWS L2VPN’s point-to-point traffic forwarding.
VPWS Overview
■ 639