science

Resource Reservation Protocol

Resource Reservation Protocol is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Resource Reservation Protocol rather than just read about it. In short: 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.

Key takeaways

Resource Reservation Protocol belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Resource Reservation Protocol to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Resource Reservation Protocol from memory before moving on to harder problems.

Reference excerpt

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. It is assigned the IP protocol number 46. RSVP can be used by hosts and routers to request or deliver specific levels of quality of service (QoS) for application data streams. RSVP defines how applications place reservations and how they can relinquish the reserved resources once no longer required. RSVP operations will generally result in resources being reserved in each node along a path. RSVP is not a routing protocol but was designed to interoperate with current and future routing protocols. In 2003, development effort was shifted from RSVP to RSVP-TE for teletraffic engineering. Next Steps in Signaling (NSIS) was a proposed replacement for RSVP.

Main attributes

RSVP requests resources for simplex flows: a traffic stream in only one direction from sender to one or more receivers. RSVP is not a routing protocol but works with current and future routing protocols. RSVP is receiver oriented in that the receiver of a data flow initiates and maintains the resource reservation for that flow. RSVP maintains soft state (the reservation at each node needs a periodic refresh) of the host and routers' resource reservations, hence supporting dynamic automatic adaptation to network changes. RSVP provides several reservation styles (a set of reservation options) and allows for future styles to be added in protocol revisions to fit varied applications. RSVP transports and maintains traffic and policy control parameters that are opaque to RSVP.

History and related standards The basic concepts of RSVP were originally proposed in 1993. RSVP is described in a series of RFC documents from the IETF:

RFC 2205: The version 1 functional specification was described in RFC 2205 (Sept. 1997) by IETF. Version 1 describes the interface to admission (traffic) control that is based "only" on resource availability. Later RFC2750 extended the admission control support. RFC 2210 defines the use of RSVP with controlled-load RFC 2211 and guaranteed RFC 2212 QoS control services. More details in Integrated Services. Also defines the usage and data format of the data objects (that carry resource reservation information) defined by RSVP in RFC 2205. RFC 2211 specifies the network element behavior required to deliver Controlled-Load services. RFC 2212 specifies the network element behavior required to deliver guaranteed QoS services. RFC 2750 describes a proposed extension for supporting generic policy based admission control in RSVP. The extension included a specification of policy objects and a description on handling policy events. (January 2000). RFC 3209, "RSVP-TE: Extensions to RSVP for LSP Tunnels" (December 2001). RFC 3473, "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions" (January 2003). RFC 3936, "Procedures for Modifying the Resource reSerVation Protocol (RSVP)" (October 2004), describes current best practices and specifies procedures for modifying RSVP. RFC 4495, "A Resource Reservation Protocol (RSVP) Extension for the Reduction of Bandwidth of a Reservation Flow" (May 2006), extends RSVP to enable the bandwidth of an existing reservation to be reduced instead of tearing down the reservation. RFC 4558, "Node-ID Based Resource Reservation Protocol (RSVP) Hello: A Clarification Statement" (June 2006).

Key concepts The two key concepts of RSVP reservation model are flowspec and filterspec.

Flowspec RSVP reserves resources for a flow. A flow is identified by the destination address, the protocol identifier, and, optionally, the destination port. In Multiprotocol Label Switching (MPLS) a flow is defined as a label-switched path (LSP). For each flow, RSVP also identifies the particular quality of service (QoS) required by the flow. This QoS information is called a flowspec and RSVP passes the flowspec from the application to the hosts and routers along the path. Those systems then analyse the flowspec to accept and reserve the resources. A flowspec consists of:

Service class Reservation spec - defines the QoS Traffic spec - describes the data flow

Filterspec The filterspec defines the set of packets that shall be affected by a flowspec (i.e., the data packets to receive the QoS defined by the flowspec). A filterspec typically selects a subset of all the packets processed by a node. The selection can depend on any attribute of a packet (e.g., the sender IP address and port). The currently defined RSVP reservation styles are:

Fixed filter - reserves resources for a specific flow. Shared explicit - reserves resources for several flows and all share the resources Wildcard filter - reserves resources for a general type of flow without specifying the flow; all flows share the resources An RSVP reservation request consists of a flowspec and a filterspec and the pair is called a flowdescriptor. The flowspec sets the parameters of the packet scheduler at a node and the filterspec sets the parameters at the packet classifier.

Messages There are two primary types of messages:

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Resource Reservation Protocol

Start with the simplest possible case. Write down what Resource Reservation Protocol claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Resource Reservation Protocol before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Resource Reservation Protocol ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Resource Reservation Protocol

In research: Resource Reservation Protocol appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Resource Reservation Protocol in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Resource Reservation Protocol is common in secondary-school and first-year university syllabi. It links to neighbouring topics Internet architecture, Internet protocols, Transport layer protocols, so understanding it makes those chapters shorter.
In everyday life: Look for Resource Reservation Protocol outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Resource Reservation Protocol in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Resource Reservation Protocol means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Resource Reservation Protocol out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Resource Reservation Protocol in simple terms?

Why does Resource Reservation Protocol matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Resource Reservation Protocol?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Resource Reservation Protocol.