A Layer 2 MPLS VPN is a term in

computer networking A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...

. It is a method that

Internet service providers An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privat ...

use to segregate their network for their customers, to allow them to transmit data over an

IP network The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

. This is often sold as a service to businesses. Layer 2 VPNs are a type of

Virtual Private Network A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The b ...

(VPN) that uses

MPLS Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identif ...

labels to transport data. The communication occurs between routers that are known as ''Provider Edge'' routers (PEs), as they sit on the edge of the provider's network, next to the customer's network. Internet providers who have an existing

Layer 2 The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer ...

network (such as ATM or

Frame Relay Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Se ...

) may choose to use these VPNs instead of the other common MPLS VPN,

Layer 3 In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers. Functions The network layer provides the means of transfe ...

. There is no one

IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements an ...

standard for Layer 2 MPLS VPNs. Instead, two methodologies may be used. Both methods use a standard MPLS header to encapsulate data. However, they differ in their signaling protocols.

Types of Layer 2 MPLS VPNs

BGP-based

The BGP-based type is based on a draft specification by Kireeti Kompella, from

Juniper Networks Juniper Networks, Inc. is an American multinational corporation headquartered in Sunnyvale, California. The company develops and markets networking products, including routers, switches, network management software, network security product ...

. It uses the

Border Gateway Protocol Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems (AS) on the Internet. BGP is classified as a path-vector routing protocol, and it make ...

(BGP) as the mechanism for PE routers to communicate with each other about their customer connections. Each router connects to a central cloud, using BGP. This means that when new customers are added (usually to new routers), the existing routers will communicate with each other, via BGP, and automatically add the new customers to the service.

LDP-based

The second type is based on a draft specification by Chandan Mishra from

Cisco Systems Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, ...

. This method is also known as a ''Layer 2 circuit''. It uses the Label Distribution Protocol (LDP) to communicate between PE routers. In this case, every LDP-speaking router will exchange FECs (forwarding equivalence classes) and establish LSPs with every other LDP-speaking router on the network (or just the other PE router, in the case when LDP is tunnelled over RSVP-TE), which differs from the BGP-based methodology. The LDP-based style of layer 2 VPN defines new TLVs and parameters for LDP to aid in the signaling of the VPNs.Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)
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Vendor implementations

* Alcatel-Lucent: LDP based *

Foundry Networks Foundry Networks, Inc. was a networking hardware vendor selling high-end Ethernet switches and routers. The company was acquired by Brocade Communications Systems on December 18, 2008. History The company was founded in 1996 by Bobby R. ...

: LDP-based (NetIron XMR Series, NetIron MLX Series) *

: BGP-based (MX/M/T/J-series) * Juniper Networks: LDP-based (MX/M/T/J/E-series) * Cisco Systems: LDP-based (IOS) * Cisco Systems: LDP-based and BGP-based (IOS XR) * Cisco Systems: LDP-Based GP-DIS

* MRV communication

LDP-based *

Lucent Technologies Lucent Technologies, Inc. was an American multinational telecommunications equipment company headquartered in Murray Hill, New Jersey. It was established on September 30, 1996, through the divestiture of the former AT&T Technologies business u ...

(formerly Riverstone Networks): LDP-based *

Ericsson (lit. "Telephone Stock Company of LM Ericsson"), commonly known as Ericsson, is a Swedish multinational networking and telecommunications company headquartered in Stockholm. The company sells infrastructure, software, and services in inform ...

(formerly

Redback Networks Redback Networks provided hardware and software used by Internet service providers to manage broadband services. The company's products included the SMS (Subscriber Management System), SmartEdge, and SmartMetro product lines. In January 2007, the ...

): LDP-based * Huawei Technologies: LDP-based & BGP-based (NE/S-series) * ZTE:LDP-based & BGP-based (ZXCTN6000/9000 series, ZXR10 series)

References

{{reflist MPLS networking