Advanced Internet Protocols, Services, and Applications

9

VIRTUAL PRIVATE WIRED SERVICE

Layer-2 virtual private network over transport can provide several features such as redundancy against failures and controlled connectivity through packet-switching or Generalized Multiprotocol Label Switching (GMPLS). Multiple Layer-2 access protocols can be virtually emulated. This chapter introduces point-to-point virtual connectivity and virtual broadcast access connectivity, such as virtual local area networks (LANs).

9.1 TYPES OF PRIVATE WIRE SERVICES

Several types of private wire services can be implemented over an Internet Protocol (IP) packet-switched network (PSN) or GMPLS network. These are:

• Virtual private LAN service (VPLS): A Layer-2 service that emulates an Ethernet virtual LAN (Ethernet VLAN) across an IP or an MPLS-enabled IP PSN.
• Virtual private wire service (VPWS): A Layer-2 service that provides point-to-point connectivity for a variety of link layers, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet, and PPP, across an IP or MPLS-enabled IP PSN.
• Virtual private multicast service (VPMS): A Layer-2 service that provides point-to-multipoint connectivity for a variety of link layers, including Frame Relay, ATM, Ethernet, and PPP, across an IP or MPLS-enabled IP PSN.
• IP-only L2VPN: A point-to-point or point-to-multipoint IP-only service over an IP or MPLS-enabled PSN. This service is similar to VPWS because it supports a variety of link-layer protocols on attachment circuits, including Frame Relay, ATM, Ethernet, ...