The Babel Routing Protocol
RFC 8966
| Document | Type | RFC - Proposed Standard (January 2021; No errata) | |
|---|---|---|---|
| Authors | Juliusz Chroboczek , David Schinazi | ||
| Last updated | 2021-01-11 | ||
| Replaces | draft-chroboczek-babel-rfc6126bis | ||
| Stream | IETF | ||
| Formats | plain text html xml pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Donald Eastlake | ||
| Shepherd write-up | Show (last changed 2019-03-26) | ||
| IESG | IESG state | RFC 8966 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Martin Vigoureux | ||
| Send notices to | Donald Eastlake <d3e3e3@gmail.com> | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
Internet Engineering Task Force (IETF) J. Chroboczek
Request for Comments: 8966 IRIF, University of Paris-Diderot
Obsoletes: 6126, 7557 D. Schinazi
Category: Standards Track Google LLC
ISSN: 2070-1721 January 2021
The Babel Routing Protocol
Abstract
Babel is a loop-avoiding, distance-vector routing protocol that is
robust and efficient both in ordinary wired networks and in wireless
mesh networks. This document describes the Babel routing protocol
and obsoletes RFC 6126 and RFC 7557.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8966.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction
1.1. Features
1.2. Limitations
1.3. Specification of Requirements
2. Conceptual Description of the Protocol
2.1. Costs, Metrics, and Neighbourship
2.2. The Bellman-Ford Algorithm
2.3. Transient Loops in Bellman-Ford
2.4. Feasibility Conditions
2.5. Solving Starvation: Sequencing Routes
2.6. Requests
2.7. Multiple Routers
2.8. Overlapping Prefixes
3. Protocol Operation
3.1. Message Transmission and Reception
3.2. Data Structures
3.3. Acknowledgments and Acknowledgment Requests
3.4. Neighbour Acquisition
3.5. Routing Table Maintenance
3.6. Route Selection
3.7. Sending Updates
3.8. Explicit Requests
4. Protocol Encoding
4.1. Data Types
4.2. Packet Format
4.3. TLV Format
4.4. Sub-TLV Format
4.5. Parser State and Encoding of Updates
4.6. Details of Specific TLVs
4.7. Details of specific sub-TLVs
5. IANA Considerations
6. Security Considerations
7. References
7.1. Normative References
7.2. Informative References
Appendix A. Cost and Metric Computation
A.1. Maintaining Hello History
A.2. Cost Computation
A.3. Route Selection and Hysteresis
Appendix B. Protocol Parameters
Appendix C. Route Filtering
Appendix D. Considerations for Protocol Extensions
Appendix E. Stub Implementations
Appendix F. Compatibility with Previous Versions
Acknowledgments
Authors' Addresses
1. Introduction
Babel is a loop-avoiding distance-vector routing protocol that is
designed to be robust and efficient both in networks using prefix-
based routing and in networks using flat routing ("mesh networks"),
and both in relatively stable wired networks and in highly dynamic
wireless networks. This document describes the Babel routing
protocol and obsoletes [RFC6126] and [RFC7557].
1.1. Features
The main property that makes Babel suitable for unstable networks is
that, unlike naive distance-vector routing protocols [RIP], it
strongly limits the frequency and duration of routing pathologies
such as routing loops and black-holes during reconvergence. Even
after a mobility event is detected, a Babel network usually remains
loop-free. Babel then quickly reconverges to a configuration that
preserves the loop-freedom and connectedness of the network, but is
not necessarily optimal; in many cases, this operation requires no
packet exchanges at all. Babel then slowly converges, in a time on
the scale of minutes, to an optimal configuration. This is achieved
by using sequenced routes, a technique pioneered by Destination-
Sequenced Distance-Vector routing [DSDV].
More precisely, Babel has the following properties:
* when every prefix is originated by at most one router, Babel never
suffers from routing loops;
* when a single prefix is originated by multiple routers, Babel may
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