Constraint-based Routing Label Distribution Protocol

Last updated

Constraint-based Routing Label Distribution Protocol (CR-LDP) is a control protocol used in some computer networks. As of February 2003, the IETF MPLS working group deprecated CR-LDP and decided to focus purely on RSVP-TE. [1]

It is an extension of the Label Distribution Protocol (LDP), one of the protocols in the Multiprotocol Label Switching architecture. CR-LDP contains extensions for LDP to extend its capabilities such as setup paths beyond what is available for the routing protocol. For instance, a label-switched path can be set up based on explicit route constraints, quality of service constraints, and other constraints. Constraint-based routing (CR) is a mechanism used to meet traffic engineering requirements. These requirements are met by extending LDP for support of constraint-based routed label-switched paths (CR-LSPs). Other uses for CR-LSPs include MPLS-based virtual private networks. CR-LDP is almost same as basic LDP, in packet structure, but it contains some extra TLVs which basically set up the constraint-based LSP.

Related Research Articles

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 identify established paths between endpoints. MPLS can encapsulate packets of various network protocols, hence the multiprotocol component of the name. MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL.

<span class="mw-page-title-main">Border Gateway Protocol</span> Protocol for communicating routing information on the Internet

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 makes routing decisions based on paths, network policies, or rule-sets configured by a network administrator.

A virtual private network (VPN) is a mechanism for creating a secure connection between a computing device and a computer network, or between two networks, using an insecure communication medium such as the public Internet.

The Resource Reservation Protocol (RSVP) is a transport layer protocol designed to reserve resources across a network using the integrated services model. RSVP operates over an IPv4 or IPv6 and provides receiver-initiated setup of resource reservations for multicast or unicast data flows. It does not transport application data but is similar to a control protocol, like Internet Control Message Protocol (ICMP) or Internet Group Management Protocol (IGMP). RSVP is described in RFC 2205.

A forwarding equivalence class (FEC) is a term used in Multiprotocol Label Switching (MPLS) to describe a set of packets with similar or identical characteristics which may be forwarded the same way; that is, they may be bound to the same MPLS label.

Label Distribution Protocol (LDP) is a protocol in which routers capable of Multiprotocol Label Switching (MPLS) exchange label mapping information. Two routers with an established session are called LDP peers and the exchange of information is bi-directional. LDP is used to build and maintain label-switched path (LSP) databases that are used to forward traffic through MPLS networks.

In computer networking and telecommunications, a pseudowire is an emulation of a point-to-point connection over a packet-switched network (PSN).

Virtual Private LAN Service (VPLS) is a way to provide Ethernet-based multipoint to multipoint communication over IP or MPLS networks. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting sites through pseudowires. The term sites includes multiplicities of both servers and clients. The technologies that can be used as pseudo-wire can be Ethernet over MPLS, L2TPv3 or even GRE. There are two IETF standards-track RFCs describing VPLS establishment.

<span class="mw-page-title-main">Metro Ethernet</span> Metropolitan area network based on Ethernet standards

A metropolitan-area Ethernet, Ethernet MAN, or metro Ethernet network is a metropolitan area network (MAN) that is based on Ethernet standards. It is commonly used to connect subscribers to a larger service network or for internet access. Businesses can also use metropolitan-area Ethernet to connect their own offices to each other.

<span class="mw-page-title-main">Layer 2 MPLS VPN</span>

A Layer 2 MPLS VPN is a term in computer networking. It is a method that Internet service providers use to segregate their network for their customers, to allow them to transmit data over an IP network. This is often sold as a service to businesses.

Automatic Switched Transport Network (ASTN) allows traffic paths to be set up through a switched network automatically. The term ASTN replaces the term ASON and is often used interchangeably with GMPLS. This is not completely correct as GMPLS is a family of protocols, but ASON/ASTN is an optical/transport network architecture. The requirements of the ASON/ASTN architecture can be satisfied using GMPLS protocols developed by the IETF or by GMPLS protocols that have been modified by the ITU. Furthermore, the GMPLS protocols are applicable to optical and non-optical networks, and can be used in transport or client networks. Thus, GMPLS is a wider concept than ASTN.

Resource Reservation Protocol - Traffic Engineering (RSVP-TE) is an extension of the Resource Reservation Protocol (RSVP) for traffic engineering. It supports the reservation of resources across an IP network. Applications running on IP end systems can use RSVP to indicate to other nodes the nature of the packet streams they want to receive. RSVP runs on both IPv4 and IPv6.

MPLS Fast Reroute is a local restoration network resiliency mechanism. It is actually a feature of resource reservation protocol (RSVP) traffic engineering (RSVP-TE). In MPLS local protection each label-switched path (LSP) passing through a facility is protected by a backup path which originates at the node immediately upstream to that facility.

In computer networks, a path computation element (PCE) is a system component, application, or network node that is capable of determining and finding a suitable route for conveying data between a source and a destination.

In telecommunications, Multiprotocol Label Switching - Transport Profile (MPLS-TP) is a variant of the MPLS protocol that is used in packet switched data networks. MPLS-TP is the product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network.

Generalized Multi-Protocol Label Switching (GMPLS) is a protocol suite extending MPLS to manage further classes of interfaces and switching technologies other than packet interfaces and switching, such as time-division multiplexing, layer-2 switching, wavelength switching and fiber-switching.

Link protection is designed to safeguard networks from failure. Failures in high-speed networks have always been a concern of utmost importance. A single fiber cut can lead to heavy losses of traffic and protection-switching techniques have been used as the key source to ensure survivability in networks. Survivability can be addressed in many layers in a network and protection can be performed at the physical layer, Layer 2 and Layer 3 (IP).

Path protection in telecommunications is an end-to-end protection scheme used in connection oriented circuits in different network architectures to protect against inevitable failures on service providers’ network that might affect the services offered to end customers. Any failure occurred at any point along the path of a circuit will cause the end nodes to move/pick the traffic to/from a new route. Finding paths with protection, especially in elastic optical networks, was considered a difficult problem, but an efficient and optimal algorithm was proposed.

HSMP LSP is hub & spoke multipoint Label Switched Path (LSP), which allows traffic both from root to leaf through point-to-multipoint (P2MP) LSP and also leaf to root along the reverse path. That means traffic entering the HSMP LSP from application/customer at the root node travels downstream to each leaf node, exactly as if it is travelling downstream along a P2MP LSP to each leaf node. Upstream traffic entering the HSMP LSP at any leaf node travels upstream along the tree to the root, as if it is unicast to the root. Direct communication among the leaf nodes is not allowed.

Deterministic Networking (DetNet) is an effort by the IETF DetNet Working Group to study implementation of deterministic data paths for real-time applications with extremely low data loss rates, packet delay variation (jitter), and bounded latency, such as audio and video streaming, industrial automation, and vehicle control.

References

  1. L. Andersson; G. Swallow (February 2003). "The Multiprotocol Label Switching (MPLS) Working Group decision on MPLS signaling protocols": 6. doi:10.17487/RFC3468. RFC   3468 .{{cite journal}}: Cite journal requires |journal= (help)