draft-ietf-babel-applicability-04.txt   draft-ietf-babel-applicability-05.txt 
Network Working Group J. Chroboczek Network Working Group J. Chroboczek
Internet-Draft IRIF, University of Paris-Diderot Internet-Draft IRIF, University of Paris-Diderot
Intended status: Informational October 23, 2018 Intended status: Informational November 14, 2018
Expires: April 26, 2019 Expires: May 18, 2019
Applicability of the Babel routing protocol Applicability of the Babel routing protocol
draft-ietf-babel-applicability-04 draft-ietf-babel-applicability-05
Abstract Abstract
Babel is a routing protocol based on the distance-vector algorithm Babel is a routing protocol based on the distance-vector algorithm
augmented with mechanisms for loop avoidance and starvation augmented with mechanisms for loop avoidance and starvation
avoidance. In this document, we argue that there exist niches where avoidance. In this document, we argue that there exist niches where
Babel is useful and that are not adequately served by more mature Babel is useful and that are not adequately served by more mature
protocols. protocols.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 26, 2019. This Internet-Draft will expire on May 18, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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2.2. Robustness 2.2. Robustness
The fairly strong properties of the Babel protocol (convergence, loop The fairly strong properties of the Babel protocol (convergence, loop
avoidance, starvation avoidance) rely on some rather weak properties avoidance, starvation avoidance) rely on some rather weak properties
of the network and the metric being used. The most significant are: of the network and the metric being used. The most significant are:
o causality: a control message is not received before it has been o causality: a control message is not received before it has been
sent (more precisely, the "happens-before" relation is acyclic); sent (more precisely, the "happens-before" relation is acyclic);
o strict monotonicity of the metric: for any metric M and link cost o strict monotonicity of the metric: for any metric M and link
C, < C + M; cost C, M < C + M;
o left-distributivity of the metric: for any metrics M and M' and o left-distributivity of the metric: for any metrics M and M' and
cost C, if M <= M', then C + M <= C + M'. cost C, if M <= M', then C + M <= C + M'.
In particular, Babel does not assume a reliable transport, it does In particular, Babel does not assume a reliable transport, it does
not assume ordered delivery, it does not assume that communication is not assume ordered delivery, it does not assume that communication is
transitive, and it does not require that the metric be discrete transitive, and it does not require that the metric be discrete
(continuous metrics are possible, reflecting for example packet loss (continuous metrics are possible, reflecting for example packet loss
rates). This is in contrast to link-state routing protocols such as rates). This is in contrast to link-state routing protocols such as
OSPF [RFC5340] or IS-IS [RFC1195], which incorporate a reliable OSPF [RFC5340] or IS-IS [RFC1195], which incorporate a reliable
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Implementors and deployers must be aware of the insecure nature of Implementors and deployers must be aware of the insecure nature of
the base protocol, and must take suitable measures to ensure that the the base protocol, and must take suitable measures to ensure that the
protocol is deployed as securely as required by the application. protocol is deployed as securely as required by the application.
6. References 6. References
6.1. Normative References 6.1. Normative References
[RFC6126bis] [RFC6126bis]
Chroboczek, J. and D. Schinazi, "The Babel Routing Chroboczek, J. and D. Schinazi, "The Babel Routing
Protocol", Internet Draft draft-ietf-babel-rfc6126bis-04, Protocol", Internet Draft draft-ietf-babel-rfc6126bis-07,
October 2017. November 2018.
6.2. Informational References 6.2. Informational References
[AODVv2] Perkins, C., Ratliff, S., Dowdell, J., Steenbrink, L., and [AODVv2] Perkins, C., Ratliff, S., Dowdell, J., Steenbrink, L., and
V. Mercieca, "Ad Hoc On-demand Distance Vector Version 2 V. Mercieca, "Ad Hoc On-demand Distance Vector Version 2
(AODVv2) Routing", draft-ietf-manet-aodvv2-16 (work in (AODVv2) Routing", draft-ietf-manet-aodvv2-16 (work in
progress), May 2016. progress), May 2016.
[BABEL-RTT] [BABEL-RTT]
Jonglez, B. and J. Chroboczek, "Delay-based Metric Jonglez, B. and J. Chroboczek, "Delay-based Metric
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