draft-ietf-6lo-backbone-router-12.txt   draft-ietf-6lo-backbone-router-13.txt 
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 6775, 8505 (if approved) C. Perkins Updates: 6775, 8505 (if approved) C. Perkins
Intended status: Standards Track Futurewei Intended status: Standards Track Futurewei
Expires: March 5, 2020 E. Levy-Abegnoli Expires: March 29, 2020 E. Levy-Abegnoli
Cisco Systems Cisco Systems
September 2, 2019 September 26, 2019
IPv6 Backbone Router IPv6 Backbone Router
draft-ietf-6lo-backbone-router-12 draft-ietf-6lo-backbone-router-13
Abstract Abstract
This document updates RFC 6775 and RFC 8505 in order to enable proxy This document updates RFC 6775 and RFC 8505 in order to enable proxy
services for IPv6 Neighbor Discovery by Routing Registrars called services for IPv6 Neighbor Discovery by Routing Registrars called
Backbone Routers. Backbone Routers are placed along the wireless Backbone Routers. Backbone Routers are placed along the wireless
edge of a Backbone, and federate multiple wireless links to form a edge of a Backbone, and federate multiple wireless links to form a
single MultiLink Subnet. single MultiLink Subnet.
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 March 5, 2020. This Internet-Draft will expire on March 29, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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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Each Backbone Router (6BBR) maintains a data structure for its Each Backbone Router (6BBR) maintains a data structure for its
Registered Nodes called a Binding Table. The combined Binding Tables Registered Nodes called a Binding Table. The combined Binding Tables
of all the 6BBRs on a backbone form a distributed database of 6LNs of all the 6BBRs on a backbone form a distributed database of 6LNs
that reside in the LLNs or on the IPv6 Backbone. that reside in the LLNs or on the IPv6 Backbone.
Unless otherwise configured, a 6BBR does the following: Unless otherwise configured, a 6BBR does the following:
o Create a new entry in a Binding Table for a new Registered Address o Create a new entry in a Binding Table for a new Registered Address
and ensure that the Address is not duplicated over the Backbone and ensure that the Address is not duplicated over the Backbone
o Defend a Registered Address over the Backbone using NA messages on
behalf of the sleeping 6LN
o Advertise a Registered Address over the Backbone using NA o Advertise a Registered Address over the Backbone using NA
messages, asynchronously or as a response to a Neighbor messages, asynchronously or as a response to a Neighbor
Solicitation messages. Solicitation messages. This includes participating to the
solicited-node multicast address associated to the Registered
Address as specified in section 7.2.1. of [RFC4861] over the
Backbone.
o Either respond using NA messages as a proxy or bridge as a unicast
frame the IPv6 ND messages (multicast DAD and Address Lookup, and
unicast NUD) received for the Registered Address over the
Backbone. This may include responding on behalf of a sleeping
node, or checking the liveliness of the Registering Node before
answering on its behalf.
o Deliver packets arriving from the LLN, using Neighbor Solicitation o Deliver packets arriving from the LLN, using Neighbor Solicitation
messages to look up the destination over the Backbone. messages to look up the destination over the Backbone.
o Forward or bridge packets between the LLN and the Backbone. o Forward or bridge packets between the LLN and the Backbone.
o Verify liveness for a registration, when needed. o Verify liveness for a registration, when needed.
The first of these functions enables the 6BBR to fulfill its role as The first of these functions enables the 6BBR to fulfill its role as
a Routing Registrar for each of its attached LLNs. The remaining a Routing Registrar for each of its attached LLNs. The remaining
functions fulfill the role of the 6BBRs as the border routers functions fulfill the role of the 6BBRs as the border routers
connecting the Multi-link IPv6 subnet to the Internet. connecting the Multi-link IPv6 subnet to the Internet.
The proxy-ND operation can co-exist with IPv6 ND over the Backbone. The proxy-ND operation can co-exist with IPv6 ND over the Backbone.
The 6BBR may co-exist with a proprietary snooping or a traditional The 6BBR may co-exist with a proprietary snooping or a traditional
bridging functionality in an Access Point, in order to support legacy bridging functionality in an Access Point, in order to support legacy
nodes that do not support this specification. In the case, the co- nodes that do not support this specification. In the case, the co-
existing function may turn multicastsinto a series of unicast to the existing function may turn multicasts into a series of unicast to the
legacy nodes. legacy nodes.
The registration to a proxy service uses an NS/NA(EARO) exchange. The registration to a proxy service uses an NS/NA(EARO) exchange.
The 6BBR operation resembles that of a Mobile IPv6 (MIPv6) [RFC6275] The 6BBR operation resembles that of a Mobile IPv6 (MIPv6) [RFC6275]
Home Agent (HA). The combination of a 6BBR and a MIPv6 HA enables Home Agent (HA). The combination of a 6BBR and a MIPv6 HA enables
full mobility support for 6LNs, inside and outside the links that full mobility support for 6LNs, inside and outside the links that
form the subnet. form the subnet.
The 6BBRs use the Extended Address Registration Option (EARO) defined The 6BBRs use the Extended Address Registration Option (EARO) defined
in [RFC8505] as follows: in [RFC8505] as follows:
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for each of the 6BBR having registered with a same TID and same ROVR. for each of the 6BBR having registered with a same TID and same ROVR.
If this registration is duplicate or not the freshest, then the 6LBR If this registration is duplicate or not the freshest, then the 6LBR
replies with an EDAC message with a status code of 1 ("Duplicate replies with an EDAC message with a status code of 1 ("Duplicate
Address") or 3 ("Moved"), respectively. If this registration is the Address") or 3 ("Moved"), respectively. If this registration is the
freshest, then the 6LBR replies with a status code of 0. In that freshest, then the 6LBR replies with a status code of 0. In that
case, if this registration is fresher than an existing registration case, if this registration is fresher than an existing registration
for another 6BBR, then the 6LBR also sends an asynchronous EDAC with for another 6BBR, then the 6LBR also sends an asynchronous EDAC with
a status of 4 ("Removed") to that other 6BBR. a status of 4 ("Removed") to that other 6BBR.
The EDAC message SHOULD carry the SLLAO used in NS messages by the The EDAR message SHOULD carry the SLLAO used in NS messages by the
6BBR for that Binding, and the EDAR message SHOULD carry the TLLAO 6BBR for that Binding, and the EDAC message SHOULD carry the TLLAO
associated with the currently accepted registration. This enables a associated with the currently accepted registration. This enables a
6BBR to locate the new position of a mobile 6LN in the case of a 6BBR to locate the new position of a mobile 6LN in the case of a
Routing Proxy operation, and opens the capability for the 6LBR to Routing Proxy operation, and opens the capability for the 6LBR to
serve as a mapping server in the future. serve as a mapping server in the future.
Note that if Link Local addresses are registered, then the scope of Note that if Link Local addresses are registered, then the scope of
uniqueness on which the address duplication is checked is the total uniqueness on which the address duplication is checked is the total
collection of links that the 6LBR serves as opposed to the sole link collection of links that the 6LBR serves as opposed to the sole link
on which the Link Local address is assigned. on which the Link Local address is assigned.
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backward compatibility with existing IPv6 hosts by setting the L flag backward compatibility with existing IPv6 hosts by setting the L flag
in the Prefix Information Option (PIO) of RA messages [RFC4861]. in the Prefix Information Option (PIO) of RA messages [RFC4861].
For movement involving a slow reattachment, the Neighbor For movement involving a slow reattachment, the Neighbor
Unreachability Detection (NUD) defined in [RFC4861] may time out too Unreachability Detection (NUD) defined in [RFC4861] may time out too
quickly. Nodes on the backbone SHOULD support [RFC7048] whenever quickly. Nodes on the backbone SHOULD support [RFC7048] whenever
possible. possible.
7. Routing Proxy Operations 7. Routing Proxy Operations
A Routing Proxy provides IPv6 ND proxy functions for Global and A Routing Proxy provides IPv6 ND proxy functions for Global including
Unique Local addresses between the LLN and the backbone, but not for Unique Local addresses between the LLN and the backbone, but not for
Link-Local addresses. It operates as an IPv6 border router and Link-Local addresses. It operates as an IPv6 border router and
provides a full Link-Layer isolation. provides a full Link-Layer isolation.
In this mode, it is not required that the MAC addresses of the 6LNs In this mode, it is not required that the MAC addresses of the 6LNs
are visible at Layer-2 over the Backbone. It is thus useful when the are visible at Layer-2 over the Backbone. It is thus useful when the
messaging over the Backbone that is associated to wireless mobility messaging over the Backbone that is associated to wireless mobility
becomes expensive, e.g., when the Layer-2 topology is virtualized becomes expensive, e.g., when the Layer-2 topology is virtualized
over a wide area IP underlay. over a wide area IP underlay.
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