draft-ietf-homenet-babel-profile-06.txt   draft-ietf-homenet-babel-profile-07.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: Standards Track February 23, 2018 Intended status: Standards Track July 18, 2018
Expires: August 27, 2018 Expires: January 19, 2019
Homenet profile of the Babel routing protocol Homenet profile of the Babel routing protocol
draft-ietf-homenet-babel-profile-06 draft-ietf-homenet-babel-profile-07
Abstract Abstract
This document defines the subset of the Babel routing protocol and This document defines the exact subset of the Babel routing protocol
its extensions that a Homenet router must implement, as well as the and its extensions that is required by an implementation of the
interactions between the Home Networking Control Protocol (HNCP) and Homenet protocol suite, as well as the interactions between the Home
Babel. Networking Control Protocol (HNCP) and Babel.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 August 27, 2018. This Internet-Draft will expire on January 19, 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
skipping to change at page 2, line 12 skipping to change at page 2, line 12
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirement Language . . . . . . . . . . . . . . . . . . 2 1.1. Requirement Language . . . . . . . . . . . . . . . . . . 2
1.2. Background . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Background . . . . . . . . . . . . . . . . . . . . . . . 2
2. The Homenet profile of Babel . . . . . . . . . . . . . . . . 3 2. The Homenet profile of Babel . . . . . . . . . . . . . . . . 3
2.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Non-requirements . . . . . . . . . . . . . . . . . . . . 5 2.2. Optional features . . . . . . . . . . . . . . . . . . . . 5
3. Interactions between HNCP and Babel . . . . . . . . . . . . . 5 3. Interactions between HNCP and Babel . . . . . . . . . . . . . 5
3.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Non-requirements . . . . . . . . . . . . . . . . . . . . 6 3.2. Optional features . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 8 7.2. Informative References . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
The core of the Homenet protocol suite consists of the Home The core of the Homenet protocol suite consists of the Home
Networking Control Protocol (HNCP) [RFC7788], a protocol used for Networking Control Protocol (HNCP) [RFC7788], a protocol used for
flooding configuration information and assigning prefixes to links, flooding configuration information and assigning prefixes to links,
skipping to change at page 2, line 44 skipping to change at page 2, line 44
This document consists of two parts. The first specifies the exact This document consists of two parts. The first specifies the exact
subset of the Babel protocol and its extensions that is required by subset of the Babel protocol and its extensions that is required by
an implementation of the Homenet protocol suite. The second an implementation of the Homenet protocol suite. The second
specifies how HNCP interacts with Babel. specifies how HNCP interacts with Babel.
1.1. Requirement Language 1.1. Requirement Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC "OPTIONAL" in this document are to be interpreted as described in BCP
2119 [RFC2119]. 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Background 1.2. Background
The Babel routing protocol and its extensions are defined in a number The Babel routing protocol and its extensions are defined in a number
of documents: of documents:
o RFC 6126bis [RFC6126bis] defines the Babel routing protocol. It o RFC 6126bis [RFC6126bis] defines the Babel routing protocol. It
allows Babel's control data to be carried either over link-local allows Babel's control data to be carried either over link-local
IPv6 or over IPv4, and in either case allows announcing both IPv4 IPv6 or over IPv4, and in either case allows announcing both IPv4
and IPv6 routes. It leaves link cost estimation, metric and IPv6 routes. It leaves link cost estimation, metric
skipping to change at page 3, line 50 skipping to change at page 3, line 50
REQ1: a Homenet implementation of Babel MUST encapsulate Babel REQ1: a Homenet implementation of Babel MUST encapsulate Babel
control traffic in IPv6 packets sent to the IANA-assigned port 6696 control traffic in IPv6 packets sent to the IANA-assigned port 6696
and either the IANA-assigned multicast group ff02::1:6 or to a link- and either the IANA-assigned multicast group ff02::1:6 or to a link-
local unicast address. local unicast address.
Rationale: since Babel is able to carry both IPv4 and IPv6 routes Rationale: since Babel is able to carry both IPv4 and IPv6 routes
over either IPv4 or IPv6, choosing the protocol used for carrying over either IPv4 or IPv6, choosing the protocol used for carrying
control traffic is a matter of preference. Since IPv6 has some control traffic is a matter of preference. Since IPv6 has some
features that make implementations somewhat simpler and more features that make implementations somewhat simpler and more
reliable (notably link-local addresses), we require carrying reliable (notably properly scoped and reasonably stable link-local
control data over IPv6. addresses), we require carrying control data over IPv6.
REQ2: a Homenet implementation of Babel MUST implement the IPv6 REQ2: a Homenet implementation of Babel MUST implement the IPv6
subset of the protocol defined in the body of RFC 6126bis. subset of the protocol defined in the body of RFC 6126bis.
Rationale: support for IPv6 routing is an essential component of Rationale: support for IPv6 routing is an essential component of
the Homenet architecture. the Homenet architecture.
REQ3: a Homenet implementation of Babel SHOULD implement the IPv4 REQ3: a Homenet implementation of Babel SHOULD implement the IPv4
subset of the protocol defined in the body of RFC 6126bis. Use of subset of the protocol defined in the body of RFC 6126bis. Use of
other techniques for acquiring IPv4 connectivity (such as multiple other techniques for acquiring IPv4 connectivity (such as multiple
skipping to change at page 4, line 32 skipping to change at page 4, line 32
REQ4: a Homenet implementation of Babel MUST implement source- REQ4: a Homenet implementation of Babel MUST implement source-
specific routing for IPv6, as defined in draft-ietf-babel-source- specific routing for IPv6, as defined in draft-ietf-babel-source-
specific [BABEL-SS]. specific [BABEL-SS].
Rationale: source-specific routing is an essential component of Rationale: source-specific routing is an essential component of
the Homenet architecture. Source-specific routing for IPv4 is not the Homenet architecture. Source-specific routing for IPv4 is not
required, since HNCP arranges things so that a single non-specific required, since HNCP arranges things so that a single non-specific
IPv4 default route is announced (Section 6.5 of [RFC7788]). IPv4 default route is announced (Section 6.5 of [RFC7788]).
REQ5: a Homenet implementation of Babel MUST use metrics that are of REQ5: a Homenet implementation of Babel must use metrics that are of
a similar magnitude to the values suggested in Appendix A of a similar magnitude to the values suggested in Appendix A of
RFC 6126bis. In particular, it SHOULD assign costs that are no less RFC 6126bis. In particular, it SHOULD assign costs that are no less
than 256 to wireless links, and SHOULD assign costs between 32 and than 256 to wireless links, and SHOULD assign costs between 32 and
196 to lossless wired links. 196 to lossless wired links.
Rationale: if two implementations of Babel choose very different Rationale: if two implementations of Babel choose very different
values for link costs, combining routers from different vendors values for link costs, combining routers from different vendors
will cause sub-optimal routing. will cause sub-optimal routing.
REQ6: a Homenet implementation of Babel SHOULD distinguish between REQ6: a Homenet implementation of Babel SHOULD distinguish between
wired and wireless links; if it is unable to determine whether a link wired and wireless links; if it is unable to determine whether a link
is wired or wireless, it SHOULD make the worst-case hypothesis that is wired or wireless, it SHOULD make the worst-case hypothesis that
the link is wireless. It SHOULD dynamically probe the quality of the link is wireless. It SHOULD dynamically probe the quality of
wireless links and derive a suitable metric from its quality wireless links and derive a suitable metric from its quality
estimation. The algorithm described in Appendix A of RFC 6126bis MAY estimation. Appendix A of RFC 6126bis gives an example of a suitable
be used. algorithm.
Rationale: support for wireless transit links is a distinguishing Rationale: support for wireless transit links is a distinguishing
feature of Homenet, and one that is requested by our users. In feature of Homenet, and one that is requested by our users. In
the absence of dynamically computed metrics, the routing protocol the absence of dynamically computed metrics, the routing protocol
attempts to minimise the number of links crossed by a route, and attempts to minimise the number of links crossed by a route, and
therefore prefers long, lossy links to shorter, lossless ones. In therefore prefers long, lossy links to shorter, lossless ones. In
wireless networks, "hop-count routing is worst-path routing". wireless networks, "hop-count routing is worst-path routing".
While it would be desirable to perform link-quality probing on While it would be desirable to perform link-quality probing on
some wired link technologies, notably power-line networks, these some wired link technologies, notably power-line networks, these
kinds of links tend to be difficult or impossible to detect kinds of links tend to be difficult or impossible to detect
automatically, and we are not aware of any published link-quality automatically, and we are not aware of any published link-quality
algorithms for them. Hence, we do not require link-quality algorithms for them. Hence, we do not require link-quality
estimation for wired links of any kind. estimation for wired links of any kind.
2.2. Non-requirements 2.2. Optional features
NR1: a Homenet implementation of Babel MAY perform route selection by OPT1: a Homenet implementation of Babel MAY perform route selection
applying hysteresis to route metrics, as suggested in Section 3.6 of by applying hysteresis to route metrics, as suggested in Section 3.6
RFC 6126bis and described in detail in Section III.E of [BABEL-RTT]. of RFC 6126bis and described in detail in Section III.E of
However, it MAY simply pick the route with the smallest metric. [BABEL-RTT]. However, hysteresis is not required, and the
implementation may simply pick the route with the smallest metric.
Rationale: hysteresis is only useful in congested and highly Rationale: hysteresis is only useful in congested and highly
dynamic networks. In a typical home network, stable and dynamic networks. In a typical home network, stable and
uncongested, the feedback loop that hysteresis compensates for uncongested, the feedback loop that hysteresis compensates for
does not occur. does not occur.
NR2: a Homenet implementation of Babel MAY include support for other OPT2: a Homenet implementation of Babel may include support for other
extensions to the protocol, as long as they are known to interoperate extensions to the protocol, as long as they are known to interoperate
with both the core protocol and source-specific routing. with both the core protocol and source-specific routing.
Rationale: a number of extensions to the Babel routing protocol Rationale: a number of extensions to the Babel routing protocol
have been defined over the years; however, they are useful in have been defined over the years; however, they are useful in
fairly specific situations, such as routing over global-scale fairly specific situations, such as routing over global-scale
overlay networks [BABEL-RTT] or multi-hop wireless networks with overlay networks [BABEL-RTT] or multi-hop wireless networks with
multiple radio frequencies [BABEL-Z]. Hence, with the exception multiple radio frequencies [BABEL-Z]. Hence, with the exception
of source-specific routing, no extensions are required for of source-specific routing, no extensions are required for
Homenet. Homenet.
3. Interactions between HNCP and Babel 3. Interactions between HNCP and Babel
The Homenet architecture cleanly separates between configuration, The Homenet architecture cleanly separates configuration, which is
which is done by HNCP, and routing, which is done by Babel. While done by HNCP, from routing, which is done by Babel. While the
the coupling between the two protocols is deliberately kept to a coupling between the two protocols is deliberately kept to a minimum,
minimum, some interactions are unavoidable. some interactions are unavoidable.
All the interactions between HNCP and Babel consist of HNCP causing All the interactions between HNCP and Babel consist of HNCP causing
Babel to perform an announcement on its behalf (under no Babel to perform an announcement on its behalf (under no
circumstances does Babel cause HNCP to perform an action). How this circumstances does Babel cause HNCP to perform an action). How this
is realised is an implementation detail that is outside the scope of is realised is an implementation detail that is outside the scope of
this document; while it could conceivably be done using a private this document; while it could conceivably be done using a private
communication channel between HNCP and Babel, in existing communication channel between HNCP and Babel, in existing
implementations HNCP installs a route in the operating system's implementations HNCP installs a route in the operating system's
kernel which is later picked up by Babel using the existing kernel which is later picked up by Babel using the existing
redistribution mechanisms. redistribution mechanisms.
skipping to change at page 6, line 39 skipping to change at page 6, line 40
a single default route towards that gateway ([RFC7788] a single default route towards that gateway ([RFC7788]
Section 6.5). Section 6.5).
REQ9: if an HNCP node assigns a prefix P to an attached link and REQ9: if an HNCP node assigns a prefix P to an attached link and
announces P in an Assigned-Prefix TLV, then it MUST announce a route announces P in an Assigned-Prefix TLV, then it MUST announce a route
towards P over Babel. towards P over Babel.
Rationale: prefixes assigned to links must be routable within the Rationale: prefixes assigned to links must be routable within the
Homenet. Homenet.
3.2. Non-requirements 3.2. Optional features
NR3: an HNCP node that receives a DHCPv6 prefix delegation MAY OPT3: an HNCP node that receives a DHCPv6 prefix delegation MAY
announce a non-specific IPv6 default route over Babel in addition to announce a non-specific IPv6 default route over Babel in addition to
the source-specific default route mandated by requirement REQ7. the source-specific default route mandated by requirement REQ7.
Rationale: since the source-specific default route is more Rationale: since the source-specific default route is more
specific than the non-specific default route, the former will specific than the non-specific default route, the former will
override the latter if all nodes implement source-specific override the latter if all nodes implement source-specific
routing. Announcing an additional non-specific route is allowed, routing. Announcing an additional non-specific route is allowed,
since doing that causes no harm and might simplify operations in since doing that causes no harm and might simplify operations in
some circumstances, e.g. when interoperating with a routing some circumstances, e.g. when interoperating with a routing
protocol that does not support source-specific routing. protocol that does not support source-specific routing.
NR4: an HNCP node that receives a DHCPv4 lease with an IPv4 address OPT4: an HNCP node that receives a DHCPv4 lease with an IPv4 address
and wins the election for NAT gateway SHOULD NOT announce a source- and wins the election for NAT gateway SHOULD NOT announce a source-
specific IPv4 default route. specific IPv4 default route.
Homenet does not require support for IPv4 source-specific routing. Homenet does not require support for IPv4 source-specific routing.
Announcing IPv4 source-specific routes will not cause routing Announcing IPv4 source-specific routes will not cause routing
pathologies (blackholes or routing loops), but it might cause pathologies (blackholes or routing loops), but it might cause
packets sourced in different parts of the Homenet to follow packets sourced in different parts of the Homenet to follow
different paths, with all the confusion that this entails. different paths, with all the confusion that this entails.
4. Security Considerations 4. Security Considerations
skipping to change at page 8, line 27 skipping to change at page 8, line 33
[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-04,
October 2017. October 2017.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking [RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016. 2016.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017.
7.2. Informative References 7.2. Informative References
[BABEL-RTT] [BABEL-RTT]
Jonglez, B. and J. Chroboczek, "Delay-based Metric Jonglez, B. and J. Chroboczek, "Delay-based Metric
Extension for the Babel Routing Protocol", draft-jonglez- Extension for the Babel Routing Protocol", draft-jonglez-
babel-rtt-extension-01 (work in progress), May 2015. babel-rtt-extension-01 (work in progress), May 2015.
[BABEL-Z] Chroboczek, J., "Diversity Routing for the Babel Routing [BABEL-Z] Chroboczek, J., "Diversity Routing for the Babel Routing
Protocol", draft-chroboczek-babel-diversity-routing-01 Protocol", draft-chroboczek-babel-diversity-routing-01
(work in progress), February 2016. (work in progress), February 2016.
 End of changes. 19 change blocks. 
31 lines changed or deleted 37 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/