draft-ietf-6man-lineid-05.txt   draft-ietf-6man-lineid-06.txt 
6man Working Group S. Krishnan 6man Working Group S. Krishnan
Internet-Draft A. Kavanagh Internet-Draft A. Kavanagh
Intended status: Experimental B. Varga Intended status: Standards Track B. Varga
Expires: December 6, 2012 Ericsson Expires: February 15, 2013 Ericsson
S. Ooghe S. Ooghe
Alcatel-Lucent Alcatel-Lucent
E. Nordmark E. Nordmark
Cisco Cisco
June 4, 2012 August 14, 2012
The Line Identification Destination Option The Line Identification Destination Option
draft-ietf-6man-lineid-05 draft-ietf-6man-lineid-06
Abstract Abstract
In Ethernet based aggregation networks, several subscriber premises In Ethernet based aggregation networks, several subscriber premises
may be logically connected to the same interface of an edge router. may be logically connected to the same interface of an edge router.
This document proposes a method for the edge router to identify the This document proposes a method for the edge router to identify the
subscriber premises using the contents of the received Router subscriber premises using the contents of the received Router
Solicitation messages. The applicability is limited to broadband Solicitation messages. The applicability is limited to broadband
network deployment scenarios where multiple user ports are mapped to network deployment scenarios where multiple user ports are mapped to
the same virtual interface on the Edge Router. the same virtual interface on the edge router.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 December 6, 2012. This Internet-Draft will expire on February 15, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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 18 skipping to change at page 2, line 18
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Conventions used in this document . . . . . . . . . . . . 5 1.2. Conventions used in this document . . . . . . . . . . . . 5
2. Applicability Statement . . . . . . . . . . . . . . . . . . . 6 2. Applicability Statement . . . . . . . . . . . . . . . . . . . 6
3. Issues with identifying the subscriber in an N:1 VLAN model . 6 3. Issues with identifying the subscriber premises in an N:1
VLAN model . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Basic operation . . . . . . . . . . . . . . . . . . . . . . . 7 4. Basic operation . . . . . . . . . . . . . . . . . . . . . . . 7
5. Access Node Behavior . . . . . . . . . . . . . . . . . . . . . 7 5. AN Behavior . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. On receiving a Router Solicitation from the end-device . . 7 5.1. On initialization . . . . . . . . . . . . . . . . . . . . 7
5.2. On receiving a Router Advertisement from the Edge 5.2. On receiving a Router Solicitation from the end-device . . 8
5.3. On receiving a Router Advertisement from the Edge
Router . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Router . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.2.1. Identifying tunneled Router Advertisements . . . . . . 8 5.3.1. Identifying tunneled Router Advertisements . . . . . . 8
5.3. On detecting a subscriber circuit coming up . . . . . . . 8 5.4. On detecting a subscriber circuit coming up . . . . . . . 8
5.4. On detecting Edge Router failure . . . . . . . . . . . . . 9 5.5. On detecting Edge Router failure . . . . . . . . . . . . . 9
5.5. RS Retransmission algorithm . . . . . . . . . . . . . . . 9 5.6. RS Retransmission algorithm . . . . . . . . . . . . . . . 9
6. Edge Router Behavior . . . . . . . . . . . . . . . . . . . . . 9 6. Edge Router Behavior . . . . . . . . . . . . . . . . . . . . . 9
6.1. On receiving a Tunneled Router Solicitation from the 6.1. On receiving a Tunneled Router Solicitation from the AN . 9
Access Node . . . . . . . . . . . . . . . . . . . . . . . 9
6.2. On sending a Router Advertisement towards the 6.2. On sending a Router Advertisement towards the
end-device . . . . . . . . . . . . . . . . . . . . . . . . 9 end-device . . . . . . . . . . . . . . . . . . . . . . . . 10
6.3. Sending periodic unsolicited Router Advertisements 6.3. Sending periodic unsolicited Router Advertisements
towards the end-device . . . . . . . . . . . . . . . . . . 10 towards the end-device . . . . . . . . . . . . . . . . . . 10
7. Line Identification Destination Option (LIO) . . . . . . . . . 10 7. Line Identification Destination Option (LIO) . . . . . . . . . 11
7.1. Encoding of Line ID . . . . . . . . . . . . . . . . . . . 11 7.1. Encoding of Line ID . . . . . . . . . . . . . . . . . . . 12
8. Garbage collection of unused prefixes . . . . . . . . . . . . 12 8. Garbage collection of unused prefixes . . . . . . . . . . . . 13
9. Interactions with Secure Neighbor Discovery . . . . . . . . . 12 9. Interactions with Secure Neighbor Discovery . . . . . . . . . 13
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
11. Security Considerations . . . . . . . . . . . . . . . . . . . 13 11. Security Considerations . . . . . . . . . . . . . . . . . . . 14
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.1. Normative References . . . . . . . . . . . . . . . . . . . 13 13.1. Normative References . . . . . . . . . . . . . . . . . . . 14
13.2. Informative References . . . . . . . . . . . . . . . . . . 14 13.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
Digital Subscriber Line (DSL) is a widely deployed access technology Digital Subscriber Line (DSL) is a widely deployed access technology
for Broadband Access for Next Generation Networks. While traditional for Broadband Access for Next Generation Networks. While traditional
DSL access networks were Point-to-Point Protocol (PPP) [RFC1661] DSL access networks were Point-to-Point Protocol (PPP) [RFC1661]
based, some networks are migrating from the traditional PPP access based, some networks are migrating from the traditional PPP access
model into a pure IP-based Ethernet aggregated access environment. model into a pure IP-based Ethernet aggregated access environment.
Architectural and topological models of an Ethernet aggregation Architectural and topological models of an Ethernet aggregation
network in the context of DSL aggregation are described in [TR101]. network in the context of DSL aggregation are described in [TR101].
skipping to change at page 4, line 41 skipping to change at page 4, line 41
scenario where each user port is mapped to scenario where each user port is mapped to
a different VLAN on the Edge Router. The a different VLAN on the Edge Router. The
uniqueness of the mapping is maintained in uniqueness of the mapping is maintained in
the Access Node and across the Aggregation the Access Node and across the Aggregation
Network. Network.
N:1 VLAN It is a broadband network deployment N:1 VLAN It is a broadband network deployment
scenario where multiple user ports are scenario where multiple user ports are
mapped to the same VLAN on the Edge Router. mapped to the same VLAN on the Edge Router.
The user ports may be located in the same The user ports may be located in the same
or different Access Nodes. or different Access Nodes.
AN A DSL or a Gigabit Passive Optical Network GPON Gigabit-capable Passive Optical Network is
(GPON) Access Node. The Access Node an optical access network that has been
terminates the physical layer (e.g. DSL introduced into the Broadband Forum
termination function or GPON termination architecture in [TR156]
function), may physically aggregate other AN A DSL or a GPON Access Node. The Access
nodes implementing such functionality, or Node terminates the physical layer (e.g.
may perform both functions at the same DSL termination function or GPON
time. This node contains at least one termination function), may physically
standard Ethernet interface that serves as aggregate other nodes implementing such
its "northbound" interface into which it functionality, or may perform both
aggregates traffic from several user ports functions at the same time. This node
or Ethernet-based "southbound" interfaces. contains at least one standard Ethernet
interface that serves as its "northbound"
It does not implement an IPv6 stack but interface into which it aggregates traffic
performs some limited inspection/ from several user ports or Ethernet-based
modification of IPv6 packets. The IPv6 "southbound" interfaces. It does not
functions required on the Access Node are implement an IPv6 stack but performs some
described in Section 5 of [TR177]. limited inspection/modification of IPv6
packets. The IPv6 functions required on
the Access Node are described in Section 5
of [TR177].
Aggregation Network The part of the network stretching from the Aggregation Network The part of the network stretching from the
Access Nodes to the Edge Router. In the Access Nodes to the Edge Router. In the
context of this document the aggregation context of this document the aggregation
network is considered to be Ethernet based, network is considered to be Ethernet based,
providing standard Ethernet interfaces at providing standard Ethernet interfaces at
the edges, for connecting the Access Nodes the edges, for connecting the Access Nodes
and Broadband Network. It is comprised of and Broadband Network. It is comprised of
ethernet switches that provide very limited ethernet switches that provide very limited
IP functionality (e.g. IGMP snooping, MLD IP functionality (e.g. IGMP snooping, MLD
snooping etc.). snooping etc.).
RG A residential gateway device. It can be a
Layer 3 (routed) device or a Layer 2
(bridged) device. The residential gateway
for Broadband Forum networks is defined in
[TR124]
Edge Router The Edge Router, also known as the Edge Router The Edge Router, also known as the
Broadband Network Gateway (BNG) is the Broadband Network Gateway (BNG) is the
first IPv6 hop for the user. In the cases first IPv6 hop for the user. In the cases
where the Residential Gateway (RG) is where the Residential Gateway (RG) is
bridged, the BNG acts as the default router bridged, the BNG acts as the default router
for the hosts behind the RG. In cases for the hosts behind the RG. In cases
where the RG is routed, the BNG acts as the where the RG is routed, the BNG acts as the
default router for the RG itself. This default router for the RG itself. This
node implements IPv6 router functionality. node implements IPv6 router functionality.
GPON Gigabit-capable Passive Optical Network is
an optical access network that has been
introduced into the Broadband Forum
architecture in [TR156]
Host A node that implements IPv6 host Host A node that implements IPv6 host
functionality. functionality.
RG A residential gateway device. It can be a
Layer 3 (routed) device or a Layer 2
(bridged) device. The residential gateway
for Broadband Forum networks is defined in
[TR124]
End-device A node that sends Router Solicitations and End-device A node that sends Router Solicitations and
processes received Router Advertisements. processes received Router Advertisements.
When a Layer 3 RG is used it is considered When a Layer 3 RG is used it is considered
an end-device in the context of this an end-device in the context of this
document. When a Layer 2 RG is used, the document. When a Layer 2 RG is used, the
host behind the RG is considered to be an host behind the RG is considered to be an
end-device in the context of this document. end-device in the context of this document.
1.2. Conventions used in this document 1.2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Applicability Statement 2. Applicability Statement
The line identification destination option is intended to be used The line identification destination option is intended to be used
only for the N:1 VLAN deployment model. For the other VLAN only for the N:1 VLAN deployment model. For the other VLAN
deployment models, line identification can be achieved differently. deployment models, line identification can be achieved differently.
The mechanism described in the document is useful for allowing the
connection of hosts that only support IPv6 stateless address auto-
configuration to attach to networks that use the N:1 VLAN deployment
model.
When the Dynamic Host Configuration Protocol (DHCP) [RFC3315] is used When the Dynamic Host Configuration Protocol (DHCP) [RFC3315] is used
for IPv6 address assignment it has the side-effect of including for IPv6 address assignment it has the side-effect of including
reliability initiated by the end-device (the end-device retransmits reliability initiated by the end-device (the end-device retransmits
DHCP messages until it receives a response), as well as a way to DHCP messages until it receives a response), as well as a way to
detect when the end-device is not active for an extended period of detect when the end-device is not active for an extended period of
time (the end-device would not renew its DHCP lease). The IPv6 time (the end-device would not renew its DHCP lease). The IPv6
Stateless address autoconfiguration protocol [RFC4862] was not Stateless address autoconfiguration protocol [RFC4862] was not
designed to satisfy such requirements. While this protocol improves designed to satisfy such requirements. While this option improves
the the robustness of relying on Router Solicitations in lieu of the reliability of operation in deployments that use Router
DHCP, this results on some limitations specified below. Solicitations rather than DHCP, there are some limitations as
specified below.
The mechanism described in this document deals with the loss of The mechanism described in this document deals with the loss of
subscriber-originated Router Solicitations (RSes) by initiating RSes subscriber-originated Router Solicitations (RSes) by initiating RSes
at the Access Node, which improves the robustness over solely relying at the AN, which improves the robustness over solely relying on the
on the end-device's few initial retransmissions of RSes. But the AN end-device's few initial retransmissions of RSes.
retransmissions imply that some information (e.g. the subscriber's
MAC address) that was obtained by the edge router from subscriber- But the AN retransmissions imply that some information (e.g. the
originated RSes may no longer be available. e.g. Since there is no subscriber's MAC address) that was obtained by the edge router from
L2 frame received from the subscriber in case of an RS sent by an AN, subscriber-originated RSes may no longer be available. e.g. Since
the L2 address information of the host cannot be determined. One there is no L2 frame received from the subscriber in case of an RS
piece of L2 address information currently used in Broadband networks sent by an AN, the L2 address information of the end-device cannot be
is the MAC address. For this reason, the solution described in this determined. One piece of L2 address information currently used in
document is NOT RECOMMENDED for networks that require the MAC address some Broadband networks is the MAC address. For this reason, the
of the endpoint for identification. solution described in this document is NOT RECOMMENDED for networks
that require the MAC address of the endpoint for identification.
There is no indication when a subscriber is no longer active. Thus There is no indication when a subscriber is no longer active. Thus
this protocol can not be used to automatically reclaim resources, this protocol can not be used to automatically reclaim resources,
such as prefixes, that are associated with an active subscriber. See such as prefixes, that are associated with an active subscriber. See
Section 8. Thus this protocol is NOT RECOMMENDED for networks that Section 8. Thus this protocol is NOT RECOMMENDED for networks that
require automatic notification when a subscriber is no longer active. require automatic notification when a subscriber is no longer active.
This mechanism by itself provides no protection against the loss of This mechanism by itself provides no protection against the loss of
RS induced state in access routers that would lead to loss of IPv6 RS induced state in access routers that would lead to loss of IPv6
connectivity for hosts. Given that regular IPv6 hosts do not have RS connectivity for end-devices. Given that regular IPv6 hosts do not
retransmission behavior that would allow automatic recovery from such have RS retransmission behavior that would allow automatic recovery
a failure, this mechanism is considered experimental and SHOULD only from such a failure, this mechanism is considered experimental and
be used in deployments employing N:1 VLANs. SHOULD only be used in deployments employing N:1 VLANs.
3. Issues with identifying the subscriber in an N:1 VLAN model 3. Issues with identifying the subscriber premises in an N:1 VLAN model
In a DSL or GPON based fixed Broadband Network, IPv6 end-devices are In a DSL or GPON based fixed Broadband Network, IPv6 end-devices are
connected to an Access Node (AN). These end-devices today will connected to an AN. These end-devices today will typically send a
typically send a Router Solicitation Message to the Edge Router, to Router Solicitation Message to the Edge Router, to which the Edge
which the Edge Router responds with a Router Advertisement message. Router responds with a Router Advertisement message. The Router
The Router Advertisement typically contains a prefix that the end- Advertisement typically contains a prefix that the end-devices will
devices will use to automatically configure an IPv6 Address. Upon use to automatically configure an IPv6 Address. Upon sending the
sending the Router Solicitation message the node connecting the end- Router Solicitation message the node connecting the end-device on the
device on the access circuit, typically an Access Node (AN), would access circuit, typically an AN, would forward the RS to the Edge
forward the RS to the Edge Router upstream over a switched network. Router upstream over a switched network. However, in such Ethernet-
However, in such Ethernet-based aggregation networks, several based aggregation networks, several subscriber premises may be
subscriber premises may be connected to the same interface of an edge connected to the same interface of an edge router (e.g. on the same
router (e.g. on the same VLAN). However, the edge router requires VLAN). However, the edge router requires some information to
some information to identify the end-device on the circuit. To identify the end-device on the circuit. To accomplish this, the AN
accomplish this, the AN needs to add line identification information needs to add line identification information to the Router
to the Router Solicitation message and forward this to the Edge Solicitation message and forward this to the Edge Router. This is
Router. This is analogous to the case where DHCP is being used, and analogous to the case where DHCP is being used, and the line
the line identification information is inserted by a DHCP relay agent identification information is inserted by a DHCP relay agent
[RFC3315]. This document proposes a method for the edge router to [RFC3315]. This document proposes a method for the edge router to
identify the subscriber premises using the contents of the received identify the subscriber premises using the contents of the received
Router Solicitation messages. Router Solicitation messages.
4. Basic operation 4. Basic operation
This document recommends tunneling Neighbor discovery packets inside This document uses a mechanism that tunnels Neighbor discovery
another IPv6 packet that uses a destination option to convey line packets inside another IPv6 packet that uses a destination option to
identification information. The Neighbor discovery packets are left convey line identification information. The Neighbor discovery
unmodified inside the encapsulating IPv6 packet. In particular, the packets are left unmodified inside the encapsulating IPv6 packet. In
Hop Limit field of the Neighbor Discovery (ND) message is not particular, the Hop Limit field of the Neighbor Discovery (ND)
decremented when the packet is being tunneled. This is because ND message is not decremented when the packet is being tunneled. This
messages whose Hop Limit is not 255 will be discarded by the receiver is because ND messages whose Hop Limit is not 255 will be discarded
of such messages. by the receiver of such messages, as described in Sections 6.1.1 and
6.1.2 of [RFC4861].
5. Access Node Behavior 5. AN Behavior
5.1. On receiving a Router Solicitation from the end-device 5.1. On initialization
On initialization, the AN MUST join the All-BBF-Access-Nodes
multicast group on all its upstream interfaces towards the Edge
Router.
5.2. On receiving a Router Solicitation from the end-device
When an end-device sends out a Router Solicitation, it is received by When an end-device sends out a Router Solicitation, it is received by
the access node. The AN identifies these messages by looking for the AN. The AN identifies these messages by looking for ICMPv6
ICMPv6 messages (IPv6 Next Header value of 58) with ICMPv6 type 133. messages (IPv6 Next Header value of 58) with ICMPv6 type 133. The AN
The AN intercepts and then tunnels the received Router Solicitation intercepts and then tunnels the received Router Solicitation in a
in a newly created IPv6 datagram with the Line Identification Option newly created IPv6 datagram with the Line Identification Option
(LIO). The AN forms a new IPv6 datagram whose payload is the (LIO). The AN forms a new IPv6 datagram whose payload is the
received Router Solicitation message as described in [RFC2473] except received Router Solicitation message as described in [RFC2473] except
that the Hop Limit field of the Router Solicitation message MUST NOT that the Hop Limit field of the Router Solicitation message MUST NOT
be decremented.If the AN has an IPv6 address, it MUST use this be decremented. If the AN has an IPv6 address, it MUST use this
address in the Source Address field of the outer IPv6 datagram. address in the Source Address field of the outer IPv6 datagram.
Otherwise, when the end-device sends out a Router Solicitation and Otherwise, the AN MUST copy the source address from the received
uses a link-local address in the Source Address field, the AN MUST Router Solicitation into the Source Address field of the outer IPv6
copy this address into the Source Address field of the outer IPv6 datagram. The destination address of the outer IPv6 datagram MUST be
datagram. In all other cases, the AN MUST use the unspecified copied from the destination address of the tunneled RS. The AN MUST
address as the Source Address of the outer IPv6 datagram. The include a destination options header between the outer IPv6 header
destination address of the outer IPv6 datagram MUST be copied from and the payload. It MUST insert a LIO destination option and set the
the destination address of the tunneled RS. The AN MUST include a line identification field of the option to contain the circuit
destination options header between the outer IPv6 header and the identifier corresponding to the logical access loop port of the AN
payload. It MUST insert a LIO destination option and set the line from which the RS was initiated.
identification field of the option to contain the circuit identifier
corresponding to the logical access loop port of the Access Node from
which the RS was initiated.
5.2. On receiving a Router Advertisement from the Edge Router 5.3. On receiving a Router Advertisement from the Edge Router
When the edge router sends out a tunneled Router Advertisement in When the edge router sends out a tunneled Router Advertisement in
response to the RS, it is received by the access node. If there is response to the RS, it is received by the AN. If there is an LIO
an LIO option present, the AN MUST use the line identification data option present, the AN MUST use the line identification data of the
of the LIO option to identify the subscriber agent circuit of the LIO option to identify the subscriber agent circuit of the AN on
Access Node on which the RA should be sent. The AN MUST then remove which the RA should be sent. The AN MUST then remove the outer IPv6
the outer IPv6 header of this tunneled RA and multicast the inner header of this tunneled RA and multicast the inner packet (the
packet (the original RA) on this specific subscriber circuit. original RA) on this specific subscriber circuit.
5.2.1. Identifying tunneled Router Advertisements 5.3.1. Identifying tunneled Router Advertisements
The Access Node can identify tunneled RAs by installing filters based The AN can identify tunneled RAs by installing filters based on the
on the destination address (All BBF Access Nodes) of the outer destination address (All-BBF-Access-Nodes which is reserved link-
packets, and the presence of a destination option header with an LIO local scoped multicast address) of the outer packets, and the
destination option. presence of a destination option header with an LIO destination
option.
5.3. On detecting a subscriber circuit coming up 5.4. On detecting a subscriber circuit coming up
RSes initiated by end-devices as described in Section 5.1 may be lost RSes initiated by end-devices as described in Section 5.2 may be lost
due to lack of connectivity between the access node and the end- due to lack of connectivity between the AN and the end-device. To
device. To ensure that the end-device will receive an RA, the AN ensure that the end-device will receive an RA, the AN needs to
needs to trigger the sending of periodic RAs on the edge router. For trigger the sending of periodic RAs on the edge router. For this
this purpose, the AN needs to inform the edge router that a purpose, the AN needs to inform the edge router that a subscriber
subscriber circuit has come up. When the access node detects that a circuit has come up. Each time the AN detects that a subscriber
subscriber circuit has come up, it MUST create a Router Solicitation circuit has come up, it MUST create a Router Solicitation message as
message as described in Section 6.3.7 of [RFC4861]. It MUST use the described in Section 6.3.7 of [RFC4861]. It MUST use the unspecified
unspecified address as the source address of this RS. It MUST then address as the source address of this RS. It MUST then tunnel this
tunnel this RS towards the edge router as described in Section 5.1. RS towards the edge router as described in Section 5.2.
In case there are connectivity issues between the AN and the edge In case there are connectivity issues between the AN and the edge
router, the RSes initiated by the AN can be lost. The AN SHOULD router, the RSes initiated by the AN can be lost. The AN SHOULD
continue retransmitting the Router Solicitations following the continue retransmitting the Router Solicitations following the
algorithm described in Section 5.5 for a given LIO until it receives algorithm described in Section 5.6 for a given LIO until it receives
an RA for that specific LIO. an RA for that specific LIO.
5.4. On detecting Edge Router failure 5.5. On detecting Edge Router failure
When the edge router reboots and loses state or is replaced by a new When the edge router reboots and loses state or is replaced by a new
edge router, the AN will detect it using connectivity check edge router, the AN will detect it using connectivity check
mechanisms that are already in place in Broadband networks (e.g. mechanisms that are already in place in Broadband networks (e.g.
BFD). When such edge router failure is detected, the AN needs to BFD). When such edge router failure is detected, the AN needs to
start transmitting RSes for each of its subscriber circuits that are start transmitting RSes for each of its subscriber circuits that are
up as described in Section 5.3. up as described in Section 5.4.
5.5. RS Retransmission algorithm 5.6. RS Retransmission algorithm
The AN SHOULD use the exponential backoff algorithm for retransmits The AN SHOULD use the exponential backoff algorithm for retransmits
that is described in Section 14 of [RFC3315] in order to continuously that is described in Section 14 of [RFC3315] in order to continuously
retransmit the Router Solicitations for a given LIO until a response retransmit the Router Solicitations for a given LIO until a response
is received for that specific LIO. The AN SHOULD use the following is received for that specific LIO. The AN SHOULD use the following
variables as input to the retransmission algorithm: variables as input to the retransmission algorithm:
IRT 1 Second IRT 1 Second
MRT 30 Seconds MRT 30 Seconds
MRC 0 MRC 0
MRD 0 MRD 0
6. Edge Router Behavior 6. Edge Router Behavior
6.1. On receiving a Tunneled Router Solicitation from the Access Node 6.1. On receiving a Tunneled Router Solicitation from the AN
When the edge router receives a tunneled Router Solicitation When the edge router receives a tunneled Router Solicitation
forwarded by the access node, it needs to check if there is an LIO forwarded by the AN, it needs to check if there is an LIO destination
destination option present in the outer datagram. The edge router option present in the outer datagram. The edge router can use the
can use the contents of the line identification field to lookup the contents of the line identification field to lookup the addressing
addressing information and policy that need to be applied to the line information and policy that need to be applied to the line from which
from which the Router Solicitation was received. The edge router the Router Solicitation was received. The edge router MUST then
MUST then process the inner RS message as specified in [RFC4861]. process the inner RS message as specified in [RFC4861].
6.2. On sending a Router Advertisement towards the end-device 6.2. On sending a Router Advertisement towards the end-device
When the edge router sends out a Router Advertisement in response to When the edge router sends out a Router Advertisement in response to
a tunneled RS that included an LIO option, it MUST tunnel the Router a tunneled RS that included an LIO option, it MUST tunnel the Router
Advertisement in a newly created IPv6 datagram with the Line Advertisement in a newly created IPv6 datagram with the Line
Identification Option (LIO). The edge router creates the Router Identification Option (LIO) as described below. First, The edge
Advertisement message as described in Section 6.2.3 of [RFC4861]. router creates the Router Advertisement message as described in
The edge router MUST include a Prefix Information Option in this RA Section 6.2.3 of [RFC4861]. The edge router MUST include a Prefix
that contains the prefix that corresponds to the received LIO. The Information Option in this RA that contains the prefix that
edge router may use the contents of the LIO in the received router corresponds to the received LIO (The LIO from the received tunneled
solicitation to determine the contents of this Router Advertisement. RS is usually passed on from the edge router to some form of
The Edge Router then forms a new IPv6 datagram, whose payload is the provisioning system that returns the prefix to be included in the RA.
Router Advertisement message, as described in [RFC2473] except that It could e,g, be based on RADIUS.). Then, the Edge Router forms the
the Hop Limit field of the Router Advertisement message MUST NOT be new IPv6 datagram, whose payload is the Router Advertisement message,
decremented. The Edge router MUST use a link-local IPv6 address on as described in [RFC2473] except that the Hop Limit field of the
the outgoing interface in the Source Address field of the outer IPv6 Router Advertisement message MUST NOT be decremented. The Edge
datagram. If the Source Address field of the received IPv6 datagram router MUST use a link-local IPv6 address on the outgoing interface
was not the unspecified address, the Edge router MUST copy this in the Source Address field of the outer IPv6 datagram. The edge
address into the Destination Address field of the outer IPv6 datagram
sent back towards the Access Node. The link-layer destination
address of the tunneled RA MUST be resolved using regular Neighbour
Discovery procedures. Otherwise, the destination address of the
outer IPv6 datagram MUST be set to the well-known link-local scope
All-BBF-Access-Nodes multicast address [to be allocated]. The edge
router MUST include a destination options header between the outer router MUST include a destination options header between the outer
IPv6 header and the payload. It MUST insert a LIO destination option IPv6 header and the payload. It MUST insert a LIO destination option
and set the line identification field of the option to contain the and set the line identification field of the option to contain the
circuit identifier corresponding to the logical access loop port of same value as that of the Line ID option in the received RS. The
the Access Node to which the RA MUST be sent. The IPv6 destination IPv6 destination address of the inner RA MUST be set to the all-nodes
address of the inner RA MUST be set to the all-nodes multicast multicast address.
address. The link-layer destination address of the tunneled RA MUST
be set to the unicast link-layer address of the Access Node that sent If the Source Address field of the received IPv6 datagram was not the
the tunneled Router Solicitation which is being responded to. unspecified address, the edge router MUST copy this address into the
Destination Address field of the outer IPv6 datagram sent back
towards the AN. The link-layer destination address of the outer IPv6
datagram containing the tunneled RA MUST be resolved using regular
Neighbour Discovery procedures.
If the Source Address field of the received IPv6 datagram was the
unspecified address, the destination address of the outer IPv6
datagram MUST be set to the well-known link-local scope All-BBF-
Access-Nodes multicast address [to be allocated]. The link-layer
destination address of the tunneled RA MUST be set to the unicast
link-layer address of the AN that sent the tunneled Router
Solicitation which is being responded to.
6.3. Sending periodic unsolicited Router Advertisements towards the 6.3. Sending periodic unsolicited Router Advertisements towards the
end-device end-device
After sending a tunneled Router Advertisement as specified in After sending a tunneled Router Advertisement as specified in
Section 6.2 in response to a received RS, the edge router MUST store Section 6.2 in response to a received RS, the edge router MUST store
the mapping between the LIO and the prefixes contained in the Router the mapping between the LIO and the prefixes contained in the Router
Advertisement. It should then initiate periodic sending of Advertisement. It should then initiate periodic sending of
unsolicited Router Advertisements as described in Section 6.2.3. of unsolicited Router Advertisements as described in Section 6.2.3. of
[RFC4861] . The Router Advertisements MUST be created and tunneled [RFC4861] . The Router Advertisements MUST be created and tunneled
as described in Section 6.2. The edge router MAY stop sending Router as described in Section 6.2. The edge router MAY stop sending Router
Advertisements if it receives a notification from the AN that the Advertisements if it receives a notification from the AN that the
subscriber circuit has gone down. This notification can be received subscriber circuit has gone down. This notification can be received
out-of-band using a mechanism such as ANCP. out-of-band using a mechanism such as ANCP. Please consult Section 8
for more details.
7. Line Identification Destination Option (LIO) 7. Line Identification Destination Option (LIO)
The Line Identification Destination Option (LIO) is a destination The Line Identification Destination Option (LIO) is a destination
option that can be included in IPv6 datagrams that tunnel Router option that can be included in IPv6 datagrams that tunnel Router
Solicitation and Router Advertisement messages. Multiple Line Solicitation and Router Advertisement messages. The use of the Line
Identification destination options MUST NOT be present in the same ID option in any other IPv6 datagrams is not defined by this
IPv6 datagram. The LIO has no alignment requirement. document. Multiple Line Identification destination options MUST NOT
be present in the same IPv6 datagram. The LIO has no alignment
requirement.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length | | Option Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LineIDLen | Line Identification... | LineIDLen | Line Identification...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Line Identification Destination Option Layout Figure 3: Line Identification Destination Option Layout
Option Type Option Type
8-bit identifier of the type of option. The option identifier 8-bit identifier of the type of option. The option identifier
for the line identification option will be allocated by the IANA. for the line identification option will be allocated by the IANA.
Option Length Option Length
8-bit unsigned integer. The length of the option (excluding 8-bit unsigned integer. The length of the option (excluding
the Option Type and Option Length fields). The value MUST be the Option Type and Option Length fields). The value MUST be
greater than 0. greater than 0.
LineIDLen LineIDLen
Length of the Line Identification field in number of octets. 8-bit unsigned integer. The length of the Line Identification
field in number of octets.
Line Identification Line Identification
Variable length data inserted by the Access Node describing the Variable length data inserted by the AN describing the
subscriber agent circuit identifier corresponding to the logical subscriber agent circuit identifier corresponding to the logical
access loop port of the Access Node from which the RS was access loop port of the AN from which the RS was
initiated. The line idenfication should be encoded as specified initiated. The line identification MUST be unique across all the
in Section 7.1. ANs that share a link to the edge router. e.g. One such line
identification scheme is described in Section 3.9 of [TR101].
The line idenfication should be encoded as specified in
Section 7.1.
7.1. Encoding of Line ID 7.1. Encoding of Line ID
This IPv6 Destination Option is derived from an existing widely This IPv6 Destination Option is derived from an existing widely
deployed DHCPv6 Option [RFC4649], which is in turn derived from a deployed DHCPv6 Option [RFC4649], which is in turn derived from a
widely deployed DHCPv4 Option [RFC3046]. Both of those derive from widely deployed DHCPv4 Option [RFC3046]. Both of those derive from
and cite the basic DHCP options specification [RFC2132]. Those and cite the basic DHCP options specification [RFC2132]. Those
widely deployed DHCP options use the NVT character set widely deployed DHCP options use the NVT character set
[RFC2132][RFC0020]. [RFC2132][RFC0020]. Since the data carried in the Line ID option is
used in the same manner by the provisioning systems as the DHCP
options, it is beneficial for it to maintain the same encoding as the
DHCP options.
The IPv6 Line ID option contains a description which identifies the The IPv6 Line ID option contains a description which identifies the
line, using only character positions (decimal 32 to decimal 126, line, using only character positions (decimal 32 to decimal 126,
inclusive) of the US-ASCII character set [X3.4], [RFC0020]. inclusive) of the US-ASCII character set [X3.4], [RFC0020].
Consistent with [RFC2132], [RFC3046] and [RFC4649], the Line ID field Consistent with [RFC2132], [RFC3046] and [RFC4649], the Line ID field
SHOULD NOT contain the US-ASCII NUL character (decimal 0). However, SHOULD NOT contain the US-ASCII NUL character (decimal 0). However,
implementations receiving this option MUST NOT fail merely because an implementations receiving this option MUST NOT fail merely because an
ASCII NUL character is (erroneously) present in the Line ID option's ASCII NUL character is (erroneously) present in the Line ID option's
data field. data field.
Some existing widely deployed implementations of edge routers and Some existing widely deployed implementations of edge routers and ANs
access nodes that support the previously mentioned DHCP option only that support the previously mentioned DHCP option only support US-
support US-ASCII, and strip the high-order bit from any 8-bit ASCII, and strip the high-order bit from any 8-bit characters entered
characters entered by the device operator. The previously mentioned by the device operator. The previously mentioned DHCP options do not
DHCP options do not support 8-bit character sets either. Therefore, support 8-bit character sets either. Therefore, for compatibility
for compatibility with the installed base and to maximise with the installed base and to maximise interoperability, the high-
interoperability, the high-order bit of each octet in this field MUST order bit of each octet in this field MUST be set to zero by any
be set to zero by any device inserting this option in an IPv6 packet. device inserting this option in an IPv6 packet.
Consistent with [RFC3046] and [RFC4649], this option always uses Consistent with [RFC3046] and [RFC4649], this option always uses
binary comparison. Therefore, two Line IDs MUST be equal when they binary comparison. Therefore, two Line IDs MUST be equal when they
match when compared byte-by-byte. Line-ID A and Line-ID B match match when compared byte-by-byte. Line-ID A and Line-ID B match
byte-by-byte when (1) A and B have the same number of bytes and (2) byte-by-byte when (1) A and B have the same number of bytes and (2)
for all byte indexes P in A: the value of A at index P has the same for all byte indexes P in A: the value of A at index P has the same
binary value as the value of B at index P. binary value as the value of B at index P.
Two Line IDs MUST NOT be equal if they do not match byte-by-byte. Two Line IDs MUST NOT be equal if they do not match byte-by-byte.
For example, an IPv6 Line ID option containing "f123" is not equal to For example, an IPv6 Line ID option containing "f123" is not equal to
skipping to change at page 13, line 10 skipping to change at page 13, line 48
Since the SEND [RFC3971] protected RS/RA packets are not modified in Since the SEND [RFC3971] protected RS/RA packets are not modified in
anyway by the mechanism described in this document, there are no anyway by the mechanism described in this document, there are no
issues with SEND verification. issues with SEND verification.
10. Acknowledgements 10. Acknowledgements
The authors would like to thank Margaret Wasserman, Mark Townsley, The authors would like to thank Margaret Wasserman, Mark Townsley,
David Miles, John Kaippallimalil, Eric Levy-Abegnoli, Thomas Narten, David Miles, John Kaippallimalil, Eric Levy-Abegnoli, Thomas Narten,
Olaf Bonness, Thomas Haag, Wojciech Dec, Brian Haberman, Ole Troan, Olaf Bonness, Thomas Haag, Wojciech Dec, Brian Haberman, Ole Troan,
Hemant Singh, Jari Arkko, Joel Halpern, Bob Hinden, Ran Atkinson and Hemant Singh, Jari Arkko, Joel Halpern, Bob Hinden, Ran Atkinson,
Glen Turner for reviewing this document and suggesting changes. Glen Turner, Kathleen Moriarty, David Sinicrope, Dan Harkins, Stephen
Farrell, Barry Leiba, Sean Turner and Ralph Droms for reviewing this
document and suggesting changes.
11. Security Considerations 11. Security Considerations
The line identification information inserted by the access node or The line identification information inserted by the AN or the edge
the edge router is not protected. This means that this option may be router is not protected. This means that this option may be
modified, inserted, or deleted without being detected. In order to modified, inserted, or deleted without being detected. In order to
ensure validity of the contents of the line identification field, the ensure validity of the contents of the line identification field, the
network between the access node and the edge router needs to be network between the AN and the edge router needs to be trusted.
trusted.
12. IANA Considerations 12. IANA Considerations
This document defines a new IPv6 destination option for carrying line This document defines a new IPv6 destination option for carrying line
identification. IANA is requested to assign a new destination option identification. IANA is requested to assign a new destination option
type in the Destination Options registry maintained at type in the Destination Options registry maintained at
http://www.iana.org/assignments/ipv6-parameters http://www.iana.org/assignments/ipv6-parameters
<TBA1> Line Identification Option [RFCXXXX] <TBA1> Line Identification Option [RFCXXXX]
skipping to change at page 13, line 42 skipping to change at page 14, line 35
The act bits for this option need to be 10 and the chg bit needs to The act bits for this option need to be 10 and the chg bit needs to
be 0. be 0.
This document also requires the allocation of a well-known link-local This document also requires the allocation of a well-known link-local
scope multicast address from the IPv6 Multicast Address Space scope multicast address from the IPv6 Multicast Address Space
Registry located at Registry located at
http://www.iana.org/assignments/ipv6-multicast-addresses/ http://www.iana.org/assignments/ipv6-multicast-addresses/
ipv6-multicast-addresses.xml ipv6-multicast-addresses.xml
<TBA2> All BBF Access Nodes [RFCXXXX] <TBA2> All-BBF-Access-Nodes [RFCXXXX]
13. References 13. References
13.1. Normative References 13.1. Normative References
[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, [RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
RFC 1661, July 1994. RFC 1661, July 1994.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
 End of changes. 55 change blocks. 
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