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Specification of the Controlled-Load Network Element Service (RFC2211) Disclosure Number: IPCOM000002769D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2019-Feb-15
Document File: 19 page(s) / 28K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Wroclawski: AUTHOR

Related Documents

10.17487/RFC2211: DOI


This memo specifies the network element behavior required to deliver Controlled-Load service in the Internet. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 7% of the total text.

Network Working Group J. Wroclawski Request For Comments: 2211 MIT LCS Category: Standards Track September 1997

Specification of the Controlled-Load Network Element Service

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.


This memo specifies the network element behavior required to deliver Controlled-Load service in the Internet. Controlled-load service provides the client data flow with a quality of service closely approximating the QoS that same flow would receive from an unloaded network element, but uses capacity (admission) control to assure that this service is received even when the network element is overloaded.

1. Introduction

This document defines the requirements for network elements that support the Controlled-Load service. This memo is one of a series of documents that specify the network element behavior required to support various qualities of service in IP internetworks. Services described in these documents are useful both in the global Internet and private IP networks.

This document is based on the service specification template given in [1]. Please refer to that document for definitions and additional information about the specification of qualities of service within the IP protocol family.

Wroclawski Standards Track [Page 1]

RFC 2211 Controlled-Load Network September 1997

2. End-to-End Behavior

The end-to-end behavior provided to an application by a series of network elements providing controlled-load service tightly approximates the behavior visible to applications receiving best- effort service *under unloaded conditions* from the same series of network elements. Assuming the network is functioning correctly, these applications may assume that:

- A very high percentage of transmitted packets will be successfully delivered by the network to the receiving end-nodes. (The percentage of packets not successfully delivered must closely approximate the basic packet error rate of the transmission medium).

- The transit delay experienced by a very high percentage of the delivered packets will not greatly exceed the minimum transmit delay experienced by any successfully delivered packet. (This minimum transit delay includes speed-of-light delay plus the fixed processing time in routers and other communications devices along the path.)

To ensure that these conditions are met, clients requesting controlled-load service provide the intermediate network elements with a estimation of the data traffic they will generate; the TSpec. In return, the service ensures that network element resources adequate to process traffic falling within this descriptive envelope will be available to the client. Should the client’s traffic genera...