draft-ietf-babel-v4viav6-00.txt   draft-ietf-babel-v4viav6-01.txt 
Network Working Group T. Bastian Network Working Group J. Chroboczek
Internet-Draft Ecole Normale Superieure, Paris Internet-Draft IRIF, University of Paris
Updates: 6126bis (if approved) J. Chroboczek Updates: 8966 (if approved) 9 April 2021
Intended status: Experimental IRIF, University of Paris-Diderot Intended status: Experimental
Expires: April 23, 2021 October 20, 2020 Expires: 11 October 2021
IPv4 routes with an IPv6 next-hop in the Babel routing protocol IPv4 routes with an IPv6 next-hop in the Babel routing protocol
draft-ietf-babel-v4viav6-00 draft-ietf-babel-v4viav6-01
Abstract Abstract
This document defines an extension to the Babel routing protocol that This document defines an extension to the Babel routing protocol that
allows annoncing routes to an IPv4 prefix with an IPv6 next-hop, allows annoncing routes to an IPv4 prefix with an IPv6 next-hop,
which makes it possible for IPv4 traffic to flow through interfaces which makes it possible for IPv4 traffic to flow through interfaces
that have not been assigned an IPv4 address. that have not been assigned an IPv4 address.
Status of This Memo Status of This Memo
skipping to change at page 1, line 34 skipping to change at page 1, line 34
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This Internet-Draft will expire on April 23, 2021. This Internet-Draft will expire on 11 October 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Specification of Requirements . . . . . . . . . . . . . . 3 1.1. Specification of Requirements . . . . . . . . . . . . . . 3
2. Protocol operation . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol operation . . . . . . . . . . . . . . . . . . . . . 3
2.1. Announcing v4-over-v6 routes . . . . . . . . . . . . . . 3 2.1. Announcing v4-via-v6 routes . . . . . . . . . . . . . . . 3
2.2. Receiving v4-over-v6 routes . . . . . . . . . . . . . . . 3 2.2. Receiving v4-via-v6 routes . . . . . . . . . . . . . . . 4
2.3. Prefix and seqno requests . . . . . . . . . . . . . . . . 4 2.3. Prefix and seqno requests . . . . . . . . . . . . . . . . 4
2.4. Other TLVs . . . . . . . . . . . . . . . . . . . . . . . 4 2.4. Other TLVs . . . . . . . . . . . . . . . . . . . . . . . 5
3. Backwards compatibility . . . . . . . . . . . . . . . . . . . 4 3. ICMPv4 and PMTU discovery . . . . . . . . . . . . . . . . . . 5
4. Protocol encoding . . . . . . . . . . . . . . . . . . . . . . 5 4. Backwards compatibility . . . . . . . . . . . . . . . . . . . 6
4.1. Prefix encoding . . . . . . . . . . . . . . . . . . . . . 5 5. Protocol encoding . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Changes for existing TLVs . . . . . . . . . . . . . . . . 5 5.1. Prefix encoding . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5.2. Changes for existing TLVs . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 7 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
Traditionally, a routing table maps a network prefix of a given Traditionally, a routing table maps a network prefix of a given
address family to a next-hop address in the same address family. The address family to a next-hop address in the same address family. The
sole purpose of this next-hop address is to serve as an input to a sole purpose of this next-hop address is to serve as an input to a
protocol that will map it to a link-layer address, Neighbour protocol that will map it to a link-layer address, Neighbour
Discovery (ND) [RFC4861] in the case of IPv6, Address Resolution Discovery (ND) [RFC4861] in the case of IPv6, Address Resolution
(ARP) [RFC0826] in the case of IPv4. Therefore, there is no reason (ARP) [RFC0826] in the case of IPv4. Therefore, there is no reason
why the address family of the next hop address should match that of why the address family of the next hop address should match that of
the prefix being announced: an IPv6 next-hop yields a link-layer the prefix being announced: an IPv6 next-hop yields a link-layer
address that is suitable for forwarding both IPv6 or IPv4 traffic. address that is suitable for forwarding both IPv6 or IPv4 traffic.
We call a route towards an IPv4 prefix that uses an IPv6 next hop a We call a route towards an IPv4 prefix that uses an IPv6 next hop a
"v4-over-v6" route. Since an IPv6 next-hop can use a link-local "v4-via-v6" route. Since an IPv6 next-hop can use a link-local
address that is autonomously configured, the use of v4-over-v6 routes address that is autonomously configured, the use of v4-via-v6 routes
enables a mode of operation where the network core has no statically enables a mode of operation where the network core has no statically
assigned IP addresses of either family, thus significantly reducing assigned IP addresses of either family, thus significantly reducing
the amount of manual configuration. the amount of manual configuration.
This document describes an extension that allows the Babel routing This document describes an extension that allows the Babel routing
protocol [RFC6126bis] to announce routes towards IPv6 prefixes with protocol [RFC8966] to announce routes towards IPv6 prefixes with IPv4
IPv4 next hops. The extension is inspired by a previously defined next hops. The extension is inspired by a previously defined
extension to the BGP protocol [RFC5549]. extension to the BGP protocol [RFC5549].
1.1. Specification of Requirements 1.1. Specification of Requirements
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 BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Protocol operation 2. Protocol operation
The Babel protocol fully supports double-stack operation: all data The Babel protocol fully supports double-stack operation: all data
that represent a neighbour address or a network prefix are tagged by that represent a neighbour address or a network prefix are tagged by
an Address Encoding (AE), a small integer that identifies the address an Address Encoding (AE), a small integer that identifies the address
family (IPv4 or IPv6) of the address of prefix, and describes how it family (IPv4 or IPv6) of the address of prefix, and describes how it
is encoded. This extension defines a new AE, called v4-over-v6, is encoded. This extension defines a new AE, called v4-via-v6, which
which has the same format as the existing AE for IPv4 addresses. has the same format as the existing AE for IPv4 addresses. This new
This new AE is only allowed in TLVs that carry network prefixes: TLVs AE is only allowed in TLVs that carry network prefixes: TLVs that
that carry a neighbour address use the normal encodings for IPv6 carry a neighbour address use the normal encodings for IPv6
addresses. addresses.
2.1. Announcing v4-over-v6 routes 2.1. Announcing v4-via-v6 routes
A Babel node that needs to announce an IPv4 route over an interface A Babel node that needs to announce an IPv4 route over an interface
that has no assigned IPv4 address MAY make a v4-over-v6 announcement. that has no assigned IPv4 address MAY make a v4-via-v6 announcement.
In order to do so, it first establishes an IPv6 next-hop address in In order to do so, it first establishes an IPv6 next-hop address in
the usual manner (either by sending the Babel packet over IPv6, or by the usual manner (either by sending the Babel packet over IPv6, or by
including a Next Hop TLV containing an IPv6 address); it then sends including a Next Hop TLV containing an IPv6 address); it then sends
an Update with AE equal to TBD containing the IPv4 prefix being an Update with AE equal to TBD containing the IPv4 prefix being
announced. announced.
If the outgoing interface has been assigned an IPv4 address, then, in If the outgoing interface has been assigned an IPv4 address, then, in
the interest of maximising compatibility with existing routers, the the interest of maximising compatibility with existing routers, the
sender SHOULD prefer an ordinary IPv4 announcement; even in that sender SHOULD prefer an ordinary IPv4 announcement; even in that
case, however, it MAY use a v4-over-v6 announcement. A node SHOULD case, however, it MAY use a v4-via-v6 announcement. A node SHOULD
NOT send both ordinary IPv4 and v4-over-v6 annoucements for the same NOT send both ordinary IPv4 and v4-via-v6 annoucements for the same
prefix over a single interface (if the update is sent to a multicast prefix over a single interface (if the update is sent to a multicast
address) or to a single neighbour (if sent to a unicast address), address) or to a single neighbour (if sent to a unicast address),
since doing that doubles the amount of routing traffic while since doing that doubles the amount of routing traffic while
providing no benefit. providing no benefit.
2.2. Receiving v4-over-v6 routes 2.2. Receiving v4-via-v6 routes
Upon reception of an Update TLV with a v4-over-v6 AE, a Babel node Upon reception of an Update TLV with a v4-via-v6 AE and finite
computes the IPv6 next-hop, as described in Section 4.6.9 of metric, a Babel node computes the IPv6 next-hop, as described in
[RFC6126bis]. If no IPv6 next-hop exists, then the Update MUST be Section 4.6.9 of [RFC8966]. If no IPv6 next-hop exists, then the
silently ignored. If an IPv6 next-hop exists, then the node MAY Update MUST be silently ignored. If an IPv6 next-hop exists, then
acquire the route being announced, as described in Section 3.5.3 of the node MAY acquire the route being announced, as described in
[RFC6126bis]; the parameters of the route are as follows: Section 3.5.3 of [RFC8966]; the parameters of the route are as
follows:
o the prefix, plen, router-id, seqno, metric MUST be computed as for * the prefix, plen, router-id, seqno, metric MUST be computed as for
an IPv4 route, as described in Section 4.6.9 of [RFC6126bis]; an IPv4 route, as described in Section 4.6.9 of [RFC8966];
o the next-hop MUST be computed as for an IPv6 route, as described * the next-hop MUST be computed as for an IPv6 route, as described
in Section 4.6.9 of [RFC6126bis]: it is taken from the last in Section 4.6.9 of [RFC8966]: it is taken from the last preceding
preceding Next-Hop TLV with an AE field equal to 2 or 3; if no Next-Hop TLV with an AE field equal to 2 or 3; if no such entry
such entry exists, and if the Update TLV has been sent in a Babel exists, and if the Update TLV has been sent in a Babel packet
packet carried over IPv6, then the next-hop is the network-layer carried over IPv6, then the next-hop is the network-layer source
source address of the packet. address of the packet.
An Update TLV with a v4-via-v6 AE and metric equal to infinity is a
retraction: it announces that a previously available route is being
retracted. In that case, no next-hop is necessary, and the
retraction is treated as described in Section 4.6.9 of [RFC8966].
As usual, a node MAY ignore the update, e.g., due to filtering As usual, a node MAY ignore the update, e.g., due to filtering
(Appendix C of [RFC6126bis]). If a node cannot install v4-over-v6 (Appendix C of [RFC8966]). If a node cannot install v4-via-v6
routes, eg., due to hardware or software limitations, then routes to routes, eg., due to hardware or software limitations, then routes to
an IPv4 prefix with an IPv6 next-hop MUST NOT be selected, as an IPv4 prefix with an IPv6 next-hop MUST NOT be selected, as
described in Section 3.5.3 of [RFC6126bis]. described in Section 3.5.3 of [RFC8966].
2.3. Prefix and seqno requests 2.3. Prefix and seqno requests
Prefix and seqno requests are used to request an update for a given Prefix and seqno requests are used to request an update for a given
prefix. Since they are not related to a specific Next-Hop, there is prefix. Since they are not related to a specific Next-Hop, there is
no semantic difference between ordinary IPv4 and v4-over-v6 requests. no semantic difference between IPv4 and v4-via-v6 requests.
Therefore, a node SHOULD NOT send requests of either kind with the AE
A node SHOULD NOT send requests of either kind with the AE field field being set to TBD (v4-via-v6); instead, it SHOULD request IPv4
being set to TBD (v4-over-v6); instead, it SHOULD request IPv4
updates using requests with the AE field being set to 1 (IPv4). updates using requests with the AE field being set to 1 (IPv4).
When receiving requests, AEs 1 (IPv4) and TBD (v4-over-v6) MUST be When receiving requests, AEs 1 (IPv4) and TBD (v4-via-v6) MUST be
treated in the same manner: the receiver processes the request as treated in the same manner: the receiver processes the request as
described in Section 3.8 of [RFC6126bis]. If an Update is sent, then described in Section 3.8 of [RFC8966]. If an Update is sent, then it
it MAY be sent with AE 1 or TBD, as described in Section 2.1 above, MAY be sent with AE 1 or TBD, as described in Section 2.1 above,
irrespective of which AE was used in the request. irrespective of which AE was used in the request.
When receiving a request with AE 0 (wildcard), the receiver SHOULD When receiving a request with AE 0 (wildcard), the receiver SHOULD
send a full route dump, as described in Section 3.8.1.1 of send a full route dump, as described in Section 3.8.1.1 of [RFC8966].
[RFC6126bis]. Any IPv4 routes contained in the route dump MAY use Any IPv4 routes contained in the route dump MAY use either AE 1 or AE
either AE 1 or AE TBD, as described in Section 2.1 above. TBD, as described in Section 2.1 above.
2.4. Other TLVs 2.4. Other TLVs
The only other TLV defined by [RFC6126bis] that carries an AE field The only other TLVs defined by [RFC8966] that carry an AE field are
is the IHU TLV. IHU TLVs MUST NOT carry the AE TBD (v4-over-v6). Next-Hop and TLV. Next-Hop and IHU TLVs MUST NOT carry the AE TBD
(v4-via-v6).
3. Backwards compatibility 3. ICMPv4 and PMTU discovery
The Internet Control Message Protocol (ICMPv4, or simply ICMP)
[RFC792] is a protocol related to IPv4 that carries diagnostic and
debugging information. ICMPv4 packets may be originated by end hosts
(e.g., the "destination unreachable, port unreachable" ICMPv4
packet), but they may also be originated by intermediate routers
(e.g., most other kinds of "destination unreachable" packets).
Path MTU Discovery (PMTUd) [RFC1191] is an algorithm executed by end
hosts to discover the maximum packet size that a route is able to
carry. While there exist variants of PMTUd that are purely end-to-
end [RFC4821], the variant most commonly deployed in the Internet has
a hard dependency on ICMPv4 packets originated by intermediate
routers: if intermediate routers are unable to send ICMPv4 packets,
PMTUd may lead to persistent blackholing of IPv4 traffic.
For that reason, every Babel router that is able to forward IPv4
traffic MUST be able originate ICMPv4 traffic. Since the extension
described in this document enables routers to forward IPv4 traffic
even when they have not been assigned an IPv4 address, a router
implementing this extension MUST be able to originate ICMPv4 packets
even when it has not been assigned an IPv4 address.
There are various ways to meet this requirement, and choosing between
them is left to the implementation. For example, if a router has an
interface that has been assigned an IPv4 address, or if it has an
IPv4 address that has been assigned to the router itself (to the
"loopback interface"), then that IPv4 address may be "borrowed" to
serve as the source of originated ICMPv4 packets. If no IPv4 address
is available, a router may use a dummy IPv4 address as the source of
outgoing ICMPv4 packets, for example an address taken from a private
address range [RFC1918] that is known to not be used in the local
routing domain. Note however that using the same address on multiple
routers may hamper debugging and fault isolation.
4. Backwards compatibility
This protocol extension adds no new TLVs or sub-TLVs. This protocol extension adds no new TLVs or sub-TLVs.
This protocol extension uses a new AE. As discussed in Appendix D of This protocol extension uses a new AE. As discussed in Appendix D of
[RFC6126bis] and specified in the same document, implementations that [RFC8966] and specified in the same document, implementations that do
do not understand the present extension will silently ignore the not understand the present extension will silently ignore the various
various TLVs that use this new AE. As a result, incompatible TLVs that use this new AE. As a result, incompatible versions will
versions will ignore v4-over-v6 routes. They will also ignore ignore v4-via-v6 routes. They will also ignore requests with AE TBD,
requests with AE TBD, which, as stated in Section 2.3, are NOT which, as stated in Section 2.3, are NOT RECOMMENDED.
RECOMMENDED.
Using a new AE introduces a new compression state, used to parse the Using a new AE introduces a new compression state, used to parse the
network prefixes. As this compression state is separate from other network prefixes. As this compression state is separate from other
AEs' states, it will not interfere with the compression state of AEs' states, it will not interfere with the compression state of
unextended nodes. unextended nodes.
This extension reuses the next-hop state from AEs 2 and 3 (IPv6), but This extension reuses the next-hop state from AEs 2 and 3 (IPv6), but
makes no changes to the way it is updated, and therefore causes no makes no changes to the way it is updated, and therefore causes no
compatibility issues. compatibility issues.
As mentioned in Section 2.1, ordinary IPv4 announcements are As mentioned in Section 2.1, ordinary IPv4 announcements are
preferred to v4-over-v6 announcements when the outgoing interface has preferred to v4-via-v6 announcements when the outgoing interface has
an assigned IPv4 address; doing otherwise would prevent routers that an assigned IPv4 address; doing otherwise would prevent routers that
do not implement this extension from learning the route being do not implement this extension from learning the route being
announced. announced.
4. Protocol encoding 5. Protocol encoding
This extension defines the v4-over-v6 AE, whose value is TBD. This This extension defines the v4-via-v6 AE, whose value is TBD. This AE
AE is solely used to tag network prefixes, and MUST NOT be used to is solely used to tag network prefixes, and MUST NOT be used to tag
tag peers' addresses, eg. in Next-Hop or IHU TLVs. peers' addresses, eg. in Next-Hop or IHU TLVs.
This extension defines no new TLVs or sub-TLVs. This extension defines no new TLVs or sub-TLVs.
4.1. Prefix encoding 5.1. Prefix encoding
Network prefixes tagged with AE TBD MUST be encoded and decoded as Network prefixes tagged with AE TBD MUST be encoded and decoded as
prefixes tagged with AE 1 (IPv4), as described in Section 4.3.1 of prefixes tagged with AE 1 (IPv4), as described in Section 4.3.1 of
[RFC6126bis]. [RFC8966].
A new compression state for AE TBD (v4-over-v6) distinct from that of A new compression state for AE TBD (v4-via-v6) distinct from that of
AE 1 (IPv4) is introduced, and MUST be used for address compression AE 1 (IPv4) is introduced, and MUST be used for address compression
of prefixes tagged with AE TBD, as described in Section 4.6.9 of of prefixes tagged with AE TBD, as described in Section 4.6.9 of
[RFC6126bis] [RFC8966]
4.2. Changes for existing TLVs 5.2. Changes for existing TLVs
The following TLVs MAY be tagged with AE TBD: The following TLVs MAY be tagged with AE TBD:
o Update (Type = 8) * Update (Type = 8)
o Route Request (Type = 9) * Route Request (Type = 9)
o Seqno Request (Type = 10)
* Seqno Request (Type = 10)
As AE TBD is suitable only to tag network prefixes, IHU (Type = 5) As AE TBD is suitable only to tag network prefixes, IHU (Type = 5)
and Next-Hop (Type = 7) TLVs MUST NOT be tagged with AE TBD. Such and Next-Hop (Type = 7) TLVs MUST NOT be tagged with AE TBD. Such
TLVs MUST be silently ignored. (incorrect) TLVs MUST be silently ignored upon reception.
4.2.1. Update 5.2.1. Update
An Update (Type = 8) TLV with AE = TBD is constructed as described in An Update (Type = 8) TLV with AE = TBD is constructed as described in
Section 4.6.9 of [RFC6126bis] for AE 1 (IPv4), with the following Section 4.6.9 of [RFC8966] for AE 1 (IPv4), with the following
specificities: specificities:
o Prefix. The Prefix field is constructed according to the * Prefix. The Prefix field is constructed according to the
Section 4.1 above. Section 5.1 above.
o Next hop. The next hop is determined as described in Section 2.2 * Next hop. The next hop is determined as described in Section 2.2
above. above.
4.2.2. Other valid TLVs tagged with AE = TBD 5.2.2. Other valid TLVs tagged with AE = TBD
Any other valid TLV tagged with AE = TBD MUST be constructed and Any other valid TLV tagged with AE = TBD MUST be constructed and
decoded as described in Section 4.6 of [RFC6126bis]. Network decoded as described in Section 4.6 of [RFC8966]. Network prefixes
prefixes within MUST be constructed and decoded as described in within MUST be constructed and decoded as described in Section 5.1
Section 4.1 above. above.
5. IANA Considerations 6. IANA Considerations
IANA is requested to allocate a value (4 suggested) in the "Babel IANA is requested to allocate a value (4 suggested) in the "Babel
Address Encodings" registry as follows: Address Encodings" registry as follows:
+-----+------------+-----------------+ +=====+===========+=================+
| AE | Name | Reference | | AE | Name | Reference |
+-----+------------+-----------------+ +=====+===========+=================+
| TBD | v4-over-v6 | (this document) | | TBD | v4-via-v6 | (this document) |
+-----+------------+-----------------+ +-----+-----------+-----------------+
6. Security Considerations Table 1
This extension does not fundamentally change the security properties 7. Security Considerations
of the Babel protocol: as described in Section 6 of [RFC6126bis],
Babel must be protected by a suitable cryptographic mechanism in
order to be made secure.
However, enabling this extension will allow IPv4 traffic to flow The extension defined in this document does not fundamentally change
through sections of a network that have not been assigned IPv4 the security properties of the Babel protocol. However, by allowing
addresses, which, in turn, might allow IPv4 traffic to reach areas of IPv4 routes to be propagated across routers that have not been
the network that were previously inaccessible to such traffic. If assigned IPv4 addresses, it might invalidate the assumptions made by
this is undesirable, the flow of IPv4 traffic must be restricted by some network administatoris, which could conceivably lead to security
the use of suitable filtering rules (Appendix C of [RFC6126bis]) issues.
together with matching access control rules in the data plane.
7. References For example, if an island of IPv4-only hosts is separated from the
IPv4 Internet by an area of routers that have not been assigned IPv4
addresses, a network administrator might reasonably assume that the
IPv4-only hosts are unreachable from the IPv4 Internet. This
assumption is broken if the intermediary routers implement the
extension described in this document, which might expose the
IPv4-only hosts to traffic from the IPv4 Internet. If this is
undesirable, the flow of IPv4 traffic must be restricted by the use
of suitable filtering rules (Appendix C of [RFC8966]) together with
matching packet filters in the data plane.
7.1. Normative References 8. Acknowledgments
This protocol extension was originally designed, described and
implemented in collaboration with Theophile Bastian. The author is
also indebted to Margaret Cullen, who pointed out the issues with
ICMP and helped coin the expression "V4-via-V6".
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997. DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC6126bis] [RFC792] Postel, J., "Internet Control Message Protocol", STD 5,
Chroboczek, J. and D. Schinazi, "The Babel Routing RFC 792, DOI 10.17487/RFC0792, September 1981,
Protocol", draft-ietf-babel-rfc6126bis-17 (work in <https://www.rfc-editor.org/info/rfc792>.
progress), February 2020.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017. May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
7.2. Informative References [RFC8966] Chroboczek, J. and D. Schinazi, "The Babel Routing
Protocol", RFC 8966, DOI 10.17487/RFC8966, January 2021,
<https://www.rfc-editor.org/info/rfc8966>.
9.2. Informative References
[RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or [RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or
Converting Network Protocol Addresses to 48.bit Ethernet Converting Network Protocol Addresses to 48.bit Ethernet
Address for Transmission on Ethernet Hardware", STD 37, Address for Transmission on Ethernet Hardware", STD 37,
RFC 826, DOI 10.17487/RFC0826, November 1982. RFC 826, DOI 10.17487/RFC0826, November 1982,
<https://www.rfc-editor.org/rfc/rfc826>.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>.
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.
J., and E. Lear, "Address Allocation for Private
Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918,
February 1996, <https://www.rfc-editor.org/info/rfc1918>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<https://www.rfc-editor.org/info/rfc4821>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007. DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/rfc/rfc4861>.
[RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network [RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
Layer Reachability Information with an IPv6 Next Hop", Layer Reachability Information with an IPv6 Next Hop",
RFC 5549, DOI 10.17487/RFC5549, May 2009. RFC 5549, DOI 10.17487/RFC5549, May 2009,
<https://www.rfc-editor.org/rfc/rfc5549>.
Authors' Addresses
Theophile Bastian Author's Address
Ecole Normale Superieure, Paris
France
Email: contact@tobast.fr
Juliusz Chroboczek Juliusz Chroboczek
IRIF, University of Paris-Diderot IRIF, University of Paris
Case 7014 Case 7014
75205 Paris Cedex 13 75205 Paris Cedex 13
France France
Email: jch@irif.fr Email: jch@irif.fr
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