wdiff rfc6788.original rfc6788.txt

6man Working Group
Internet Engineering Task Force (IETF) S. Krishnan
Internet-Draft
Request for Comments: 6788 A. Kavanagh
Intended status:
Category: Standards Track B. Varga
Expires: February 18, 2013
ISSN: 2070-1721 Ericsson
S. Ooghe
Alcatel-Lucent
E. Nordmark
Cisco
August 17,
November 2012

The Line Identification Line-Identification Destination Option
draft-ietf-6man-lineid-08

Abstract

In Ethernet based Ethernet-based aggregation networks, several subscriber premises
may be logically connected to the same interface of an edge router. Edge Router.
This document proposes a method for the edge router Edge Router to identify the
subscriber premises using the contents of the received Router
Solicitation messages. The applicability is limited to broadband
network deployment scenarios where in which multiple user ports are mapped
to the same virtual interface on the edge router. Edge Router.

Status of this This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of six months this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on February 18, 2013.
http://www.rfc-editor.org/info/rfc6788.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 ....................................................3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 ................................................4
1.2. Conventions used Used in this document . . . . . . . . . . . . 5 This Document ..........................6
2. Applicability Statement . . . . . . . . . . . . . . . . . . . 6 .........................................6
3. Issues with identifying Identifying the subscriber premises Subscriber Premises in an
N:1 VLAN model . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Model ..................................................7
4. Basic operation . . . . . . . . . . . . . . . . . . . . . . . 7 Operation .................................................7
5. AN Behavior . . . . . . . . . . . . . . . . . . . . . . . . . 8 .....................................................8
5.1. On initialization . . . . . . . . . . . . . . . . . . . . 8 Initialization ..........................................8
5.2. On receiving Receiving a Router Solicitation from the end-device . . 8 End-Device .....8
5.3. On receiving Receiving a Router Advertisement from the Edge Router . . . . . . . . . . . . . . . . . . . . . . . . . . 9 ...9
5.3.1. Identifying tunneled Tunneled Router Advertisements . . . . . . 9 ..........9
5.4. On detecting Detecting a subscriber circuit coming up . . . . . . . 9 Subscriber Circuit Coming Up ................9
5.5. On detecting Detecting Edge Router failure . . . . . . . . . . . . . 9 Failure ..........................10
5.6. RS Retransmission algorithm . . . . . . . . . . . . . . . 10 Algorithm ...............................10
6. Edge Router Behavior . . . . . . . . . . . . . . . . . . . . . 10 ...........................................10
6.1. On receiving Receiving a Tunneled Router Solicitation from the AN . 10 ...10
6.2. On sending Sending a Router Advertisement towards Towards the
end-device . . . . . . . . . . . . . . . . . . . . . . . . 10 End-Device ..10
6.3. Sending periodic unsolicited Periodic Unsolicited Router Advertisements
towards
Towards the end-device . . . . . . . . . . . . . . . . . . 11 End-Device ....................................11
7. Line Identification Destination Option (LIO) . . . . . . . . . 11 ...................12
7.1. Encoding of Line ID . . . . . . . . . . . . . . . . . . . 12 .......................................13
8. Garbage collection Collection of unused prefixes . . . . . . . . . . . . 13 Unused Prefixes ..........................14
9. Interactions with Secure Neighbor Discovery . . . . . . . . . 14
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
11. Security Considerations . . . . . . . . . . . . . . . . . . . 14
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Interactions with Secure Neighbor Discovery ....................14
10. Acknowledgements ..............................................14
11. Security Considerations .......................................14
12. IANA Considerations ...........................................14
13. References ....................................................15
13.1. Normative References . . . . . . . . . . . . . . . . . . . 15 .....................................15
13.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 ...................................16

1. Introduction

Digital Subscriber Line (DSL) is a widely deployed access technology
for Broadband Access for Next Generation Networks. While traditional
DSL access networks were Point-to-Point Protocol (PPP) [RFC1661]
based, some networks are migrating from the traditional PPP access
model into a pure IP-based Ethernet aggregated access environment.
Architectural and topological models of an Ethernet aggregation
network in the context of DSL aggregation are described in [TR101].

+----+ +----+ +----------+
|Host|---| RG |----| |
+----+ +----+ | |
| AN |\
+----+ +----+ | | \
|Host|---| RG |----| | \
+----+ +----+ +----------+ \ +----------+
\ | |
+-------------+ | |
| Aggregation | | Edge |
| Network |-------| Router |
+-------------+ | |
/ | |
+----------+ / +----------+
| | /
+----+ +----+ | | /
|Host|---| RG |----| AN |/
+----+ +----+ | |
| |
+----------+

Figure 1: Broadband Forum Network Architecture
One of the Ethernet and Gigabit Gigabit-capable Passive Optical Network
(GPON) aggregation models specified in this document bridges sessions
from multiple user ports behind a DSL Access Node (AN), also referred
to as a Digital subscriber line access multiplexer Subscriber Line Access Multiplexer (DSLAM), into a
single VLAN in the aggregation network. This is called the N:1 VLAN
allocation model.

+----------+
| |
| |
| AN |\
| | \
| | \ VLANx
+----------+ \ +----------+
\ | |
+-------------+ | |
| Aggregation | VLANx | Edge |
| Network |-------| Router |
+-------------+ | |
/ | |
+----------+ / +----------+
| | / VLANx
| | /
| AN |/
| |
| |
+----------+

Figure 2: n:1 VLAN model

1.1. Terminology

1:1 VLAN It is a A broadband network deployment scenario where in
which each user port is mapped to a different
VLAN on the Edge Router. The uniqueness of
the mapping is maintained in the Access Node
and across the Aggregation
Network. aggregation network.

N:1 VLAN It is a A broadband network deployment scenario where in
which multiple user ports are mapped to the
same VLAN on the Edge Router. The user ports
may be located in the same or different Access
Nodes.

GPON Gigabit-capable Passive Optical Network is an
optical access network that has been
introduced into the Broadband Forum
architecture in [TR156] [TR156].

AN A DSL or a GPON Access Node. The Access Node
terminates the physical layer (e.g. (e.g., DSL
termination function or GPON termination
function), may physically aggregate other
nodes implementing such functionality, or may
perform both functions at the same time. This
node contains at least one standard Ethernet
interface that serves as its "northbound"
interface into which it aggregates traffic
from several user ports or Ethernet-based
"southbound" interfaces. It does not
implement an IPv6 stack but performs some
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
Access Nodes to the Edge Router. In the
context of this document document, the aggregation
network is considered to be Ethernet based,
providing standard Ethernet interfaces at the
edges, for connecting the Access Nodes and Broadband Network. the
broadband network. It is comprised of
ethernet
Ethernet switches that provide very limited IP
functionality (e.g. (e.g., IGMP snooping, MLD
snooping Multicast
Listener Discovery (MLD) snooping, etc.).

RG A residential gateway device. It can be a
Layer 3
Layer-3 (routed) device or a Layer 2 Layer-2 (bridged)
device. The residential gateway for Broadband
Forum networks is defined in
[TR124] [TR124].

Edge Router The Edge Router, also known as the Broadband
Network Gateway (BNG) (BNG), is the first IPv6 hop
for the user. In the cases where the Residential Gateway (RG) RG is
bridged, the BNG acts as the default router
for the hosts behind the RG. In cases where
the RG is routed, the BNG acts as the default
router for the RG itself. This node
implements IPv6 router functionality.

Host A node that implements IPv6 host
functionality.
End-device

End-Device A node that sends Router Solicitations and
processes received Router Advertisements.
When a Layer 3 Layer-3 (L3) RG is used used, it is
considered an end-device in the context of
this document. When a Layer 2 Layer-2 (L2) RG is
used, the host behind the RG is considered to
be an end-device in the context of this
document.

1.2. Conventions used Used in this document This Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].

2. Applicability Statement

The line identification destination option Line Identification Destination Option (LIO) is intended to be
used only for the N:1 VLAN deployment model. For the other VLAN
deployment models, line identification can be achieved differently.
The mechanism described in the this document is useful for allowing allows the connection of
hosts that only support IPv6 stateless address auto-
configuration auto-configuration to
attach to networks that use the N:1 VLAN deployment model.

When the Dynamic Host Configuration Protocol (DHCP) [RFC3315] is used
for IPv6 address assignment assignment, it has the side-effect of including providing end-
device-initiated reliability initiated as well as inactivity detection. The
reliability is provided by the end-device (the end-device retransmits continuing to retransmit
DHCP messages until it receives a response), as well as a way to
detect when the end-device and inactivity is not active for an extended period of
time (the
detected by the end-device would not renew renewing its DHCP lease). lease. The IPv6 "IPv6
Stateless address autoconfiguration Address Autoconfiguration" protocol [RFC4862] was not
designed to satisfy such requirements [RSDA]. While this option
improves the reliability of operation in deployments that use Router
Solicitations rather than DHCP, there are some limitations as
specified below.

The mechanism described in this document deals with the loss of
subscriber-originated Router Solicitations (RSes) by initiating RSes
at the AN, which improves the robustness over solely relying on the
end-device's few initial retransmissions of RSes.

But

However, the AN retransmissions imply that some information (e.g. (e.g.,
the subscriber's MAC address) that was obtained by the edge router Edge Router
from subscriber-originated RSes may no longer be available. e.g. Since For
example, since there is no L2 frame received from the subscriber in
case of an RS sent by an AN, the L2 address L2-address information of the
end-device cannot be determined. One piece of L2 address L2-address information
currently used in some Broadband broadband networks is the MAC address. For
this reason, the 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 Thus,
this protocol can not cannot be used to automatically reclaim resources, such
as prefixes, that are associated with an active subscriber. See
Section 8. Thus Thus, this protocol is NOT RECOMMENDED for networks that
require automatic notification when a subscriber is no longer active.

This mechanism by itself provides no protection against the loss of
RS induced
RS-induced state in access routers that would lead to loss of IPv6
connectivity for end-devices. Given that regular IPv6 hosts do not
have RS retransmission behavior that would allow automatic recovery
from such a failure, this mechanism SHOULD only be used in
deployments employing N:1 VLANs.

3. Issues with identifying Identifying the subscriber premises Subscriber Premises in an N:1 VLAN model Model

In a DSL DSL- or GPON based GPON-based fixed Broadband Network, broadband network, IPv6 end-devices are
connected to an AN. These Today, these end-devices today will typically send a
Router Solicitation Message message to the Edge Router, to which the Edge
Router responds with a Router Advertisement message. The Router
Advertisement typically contains a prefix that the end-devices will
use to automatically configure an IPv6 Address. address. Upon sending the
Router Solicitation message message, the node connecting the end-device on
the access circuit, typically an AN, would forward forwards the RS to the Edge
Router upstream over a switched network. However, in In such Ethernet-
based Ethernet-based
aggregation networks, several subscriber premises may be connected to
the same interface of an edge router (e.g. Edge Router (e.g., on the same VLAN).
However, the edge router Edge Router requires some information to identify the
end-device on the circuit. To accomplish this, the AN needs to add line identification
line-identification information to the Router Solicitation message
and forward this to the Edge Router. This is analogous to the case
where DHCP is being used, and the line
identification line-identification information is
inserted by a DHCP relay agent [RFC3315]. This document proposes a
method for the edge router Edge Router to identify the subscriber premises using
the contents of the received Router Solicitation messages. Note that
there might be several end-
devices that are end-devices located on the same subscriber
premises.

4. Basic operation Operation

This document uses a mechanism that tunnels Neighbor discovery Discovery (ND)
packets inside another IPv6 packet that uses a destination option
(Line ID option) to convey line identification line-identification information as
depicted in Figure 3. The use of the Line ID option in any other
IPv6 datagrams, including untunneled RS and RA messages, is not
defined by this document. The Neighbor discovery ND packets are left unmodified inside
the encapsulating IPv6 packet. In particular, the Hop Limit field of
the Neighbor Discovery (ND) ND message is not decremented when the packet is being tunneled.
This is because an ND
messages message whose Hop Limit is not 255 will be
discarded by the receiver of such messages, as described in Sections
6.1.1 and 6.1.2 of [RFC4861].

+----+ +----+ +-----------+
|Host| | AN | |Edge Router|
+----+ +----+ +-----------+
| RS | |
|---------->| |
| | |
| |Tunneled RS(LIO)|
| |--------------->|
| | |
| |Tunneled RA(LIO)|
| |<---------------|
| RA | |
|<----------| |
| | |

Figure 3: Basic message flow Message Flow

5. AN Behavior

5.1. On initialization 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 Receiving a Router Solicitation from the end-device End-Device

When an end-device sends out a Router Solicitation, it is received by
the AN. The AN identifies these messages by looking for ICMPv6
messages (IPv6 Next Header value of 58) with ICMPv6 type 133. The AN
intercepts and then tunnels the received Router Solicitation in a
newly created IPv6 datagram with the Line Identification ID Option (LIO). The AN
forms a new IPv6 datagram whose payload is the received Router
Solicitation message as described in [RFC2473] [RFC2473], except 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 address
in the Source Address field of the outer IPv6 datagram. Otherwise,
the AN MUST copy the source address from the received Router
Solicitation into the Source Address field of the outer IPv6
datagram. The destination address of the outer IPv6 datagram MUST be
copied from the destination address of the tunneled RS. The AN MUST
include a destination options header between the outer IPv6 header
and the payload. It MUST insert a an LIO destination option and set
the
line identification Line ID field of the option to contain the circuit identifier
corresponding to the logical access loop port of the AN from which
the RS was initiated.

5.3. On receiving Receiving a Router Advertisement from the Edge Router

When the edge router Edge Router sends out a tunneled Router Advertisement in
response to the RS, it is received by the AN. If there is an LIO
option
present, the AN MUST use the line identification line-identification data of the LIO option to
identify the subscriber agent circuit of the AN on which the RA
should be sent. The AN MUST then remove the outer IPv6 header of
this tunneled RA and multicast the inner packet (the original RA) on
this specific subscriber circuit.

5.3.1. Identifying tunneled Tunneled Router Advertisements

The AN can identify tunneled RAs by installing filters based on the
destination address (All-BBF-Access-Nodes (All-BBF-Access-Nodes, which is a reserved link-
local
link-local scoped multicast address) of the outer packets, packets and the
presence of a destination option header with an LIO destination
option.

5.4. On detecting Detecting a subscriber circuit coming up Subscriber Circuit Coming Up

RSes initiated by end-devices as described in Section 5.2 may be lost
due to lack of connectivity between the AN and the end-device. To
ensure that the end-device will receive an RA, the AN needs to
trigger the sending of periodic RAs on the edge router. Edge Router. For this
purpose, the AN needs to inform the edge router Edge Router that a subscriber
circuit has come up. Each time the AN detects that a subscriber
circuit has come up, it MUST create a Router Solicitation message as
described in Section 6.3.7 of [RFC4861]. It MUST use the unspecified
address as the source address of this RS. It MUST then tunnel this
RS towards the edge router Edge Router as described in Section 5.2.

In case there are connectivity issues between the AN and the edge
router, Edge
Router, the RSes initiated by the AN can be lost. The AN SHOULD
continue retransmitting the Router Solicitations following the
algorithm described in Section 5.6 for a given LIO until it receives
an RA for that specific LIO.

5.5. On detecting Detecting Edge Router failure Failure

When the edge router Edge Router reboots and loses state or is replaced by a new
edge router,
Edge Router, the AN will detect it using connectivity check
mechanisms that are already in place in Broadband broadband networks (e.g.
BFD). (e.g.,
Bidirectional Forwarding Detection). When such edge router Edge Router failure
is detected, the AN needs to start transmitting RSes for each of its
subscriber circuits that are
up have come up, as described in Section 5.4.

5.6. RS Retransmission algorithm Algorithm

The AN SHOULD use the exponential backoff algorithm for retransmits
that is described in Section 14 of [RFC3315] in order to continuously
retransmit the Router Solicitations for a given LIO until a response
is received for that specific LIO. The AN SHOULD use the following
variables as input to the retransmission algorithm:

IRT

Initial retransmission time (IRT) 1 Second
MRT
Maximum retransmission time (MRT) 30 Seconds
MRC
Maximum retransmission count (MRC) 0
MRD
Maximum retransmission duration (MRD) 0

6. Edge Router Behavior

6.1. On receiving Receiving a Tunneled Router Solicitation from the AN

When the edge router Edge Router receives a tunneled Router Solicitation
forwarded by the AN, it needs to check if there is an LIO destination
option present in the outer datagram. The edge router Edge Router can use the
contents of the line identification Line ID field to lookup the addressing information
and policy that need to be applied to the line from which the Router
Solicitation was received. The edge router Edge Router MUST then process the
inner RS message as specified in [RFC4861].

6.2. On sending Sending a Router Advertisement towards Towards the end-device End-Device

When the edge router Edge Router sends out a Router Advertisement in response to
a tunneled RS that included an LIO option, LIO, it MUST tunnel the Router
Advertisement in a newly created IPv6 datagram with the Line
Identification Option (LIO) LIO as
described below. First, The edge
router the Edge Router creates the Router
Advertisement message as described in Section 6.2.3 of [RFC4861].
The edge router Edge Router MUST include a Prefix Information Option option in this RA
that contains the prefix that corresponds to the received LIO LIO. (The
LIO from the received tunneled RS is usually passed on from the edge router Edge
Router to some form of provisioning system that returns the prefix to
be included in the RA. It could e,g, e,g., be based on RADIUS.). RADIUS.) Then,
the Edge Router forms the new IPv6 datagram, datagram whose payload is the
Router Advertisement message, as described in [RFC2473] [RFC2473], except that
the Hop Limit field of the Router Advertisement message MUST NOT be
decremented. The Edge router MUST use a link-local IPv6 address on
the outgoing interface in the Source Address field of the outer IPv6
datagram. The edge
router Edge Router MUST include a destination options header
between the outer IPv6 header and the payload. It MUST insert a an LIO destination option
and set the line identification Line ID field of the option to contain the same value as
that of the Line ID option in the received RS. The IPv6 destination
address of the inner RA MUST be set to the all-nodes multicast
address.

If the Source Address field of the received IPv6 datagram was not the
unspecified address, the edge router 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 outer IPv6 datagram MUST be resolved using
regular Neighbour Neighbor 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
All-BBF-Access-Nodes multicast address [to be allocated]. (ff02::10). 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 that is being responded to.

The edge router Edge Router MUST ensure that it does not transmit tunneled RAs
whose size is larger than the MTU of the link between the edge router Edge Router
and the AN, which would require that the outer IPv6 datagram undergo
fragmentation. This limitation is imposed because the AN may not be
capable of handling the reassembly of such fragmented datagrams.

6.3. Sending periodic unsolicited Periodic Unsolicited Router Advertisements towards Towards the
end-device
End-Device

After sending a tunneled Router Advertisement as specified in Section
6.2 in response to a received RS, the edge router Edge Router MUST store the
mapping between the LIO and the prefixes contained in the Router
Advertisement. It should then initiate periodic sending of
unsolicited Router Advertisements as described in Section 6.2.3. of
[RFC4861] . The Router Advertisements MUST be created and tunneled
as described in Section 6.2. The edge router Edge Router MAY stop sending Router
Advertisements if it receives a notification from the AN that the
subscriber circuit has gone down. This notification can be received
out-of-band using a mechanism such as ANCP. the Access Node Control
Protocol (ANCP). Please consult Section 8 for more details.

7. Line Identification Destination Option (LIO)

The Line Identification Destination Option (LIO) is a destination
option that can be included in IPv6 datagrams that tunnel Router
Solicitation and Router Advertisement messages. The use of the Line
ID option in any other IPv6 datagrams is not defined by this
document. Multiple Line Identification ID 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 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LineIDLen | Line Identification...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4: Line Identification Destination Option Layout

Option Type

8-bit identifier of the type of option. The option identifier
for the line identification option will be Line Identification Option (0x8C) has been allocated by
the IANA.

Option Length

8-bit unsigned integer. The length of the option (excluding the
Option Type and Option Length fields). The value MUST be greater
than 0.

LineIDLen

8-bit unsigned integer. The length of the Line Identification ID field in
number of octets.

Line Identification

Variable length

Variable-length data inserted by the AN describing the
subscriber agent
subscriber-agent circuit identifier corresponding to the logical
access loop port of the AN from which the RS was initiated. The
line identification MUST be unique across all the ANs that share
a link to the edge router. e.g. One Edge Router, e.g., one such line line- identification
scheme is described in Section 3.9 of [TR101]. The line idenfication
identification should be encoded as specified in Section 7.1.

7.1. Encoding of Line ID Identification

This IPv6 Destination Option option is derived from an existing widely
deployed DHCPv6 Option option [RFC4649], which is in turn derived from a
widely deployed DHCPv4 Option option [RFC3046]. Both of those These options derive from
and cite the basic DHCP options specification [RFC2132]. Those These
widely deployed DHCP options use the NVT Network Virtual Terminal (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 that identifies the
line,
line using only character positions (decimal 32 to decimal 126,
inclusive) of the US-ASCII character set [X3.4], [X3.4] [RFC0020].
Consistent with [RFC2132], [RFC3046] [RFC3046], and [RFC4649], the Line ID
field SHOULD NOT contain the US-ASCII NUL character (decimal 0).
However, implementations receiving this option MUST NOT fail merely
because an ASCII NUL character is (erroneously) present in the Line
ID option's data field.

Some existing widely deployed implementations of edge routers Edge Routers and ANs
that support the previously mentioned DHCP option only support US-
ASCII,
US-ASCII and strip the high-order bit from any 8-bit characters
entered by the device operator. The previously mentioned DHCP
options do not support 8-bit character sets either. Therefore, for
compatibility with the installed base and to maximise maximize
interoperability, the high-
order high-order bit of each octet in this field MUST
be set to zero by any device inserting this option in an IPv6 packet.

Consistent with [RFC3046] and [RFC4649], this option always uses
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
byte-by-byte when (1) A and B have the same number of bytes bytes, and (2)
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.

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
a Line ID option "F123".

Intermediate systems MUST NOT alter the contents of the Line ID.

8. Garbage collection Collection of unused prefixes Unused Prefixes

Following the mechanism described in this document, the Broadband broadband
network associates a prefix to a subscriber line based on the LIO.
Even when the subscriber line goes down temporarily, this prefix
stays allocated to that specific subscriber line. i.e. The line, i.e., the prefix is
not returned to the unused pool. When a subscriber line no longer
needs a prefix, the prefix can be reclaimed by manual action
dissociating the prefix from the LIO in the backend systems.

9. Interactions with Secure Neighbor Discovery

Since the SEND [RFC3971] protected RS/RA packets that are protected by the "SEcure Neighbor
Discovery (SEND)" [RFC3971] are not modified in
anyway any way by the
mechanism described in this document, there are no issues with SEND
verification.

10. Acknowledgements

The authors would like to thank Margaret Wasserman, Mark Townsley,
David Miles, John Kaippallimalil, Eric Levy-Abegnoli, Thomas Narten,
Olaf Bonness, Thomas Haag, Wojciech Dec, Brian Haberman, Ole Troan,
Hemant Singh, Jari Arkko, Joel Halpern, Bob Hinden, Ran Atkinson,
Glen Turner, Kathleen Moriarty, David Sinicrope, Dan Harkins, Stephen
Farrell, Barry Leiba, Sean Turner, Ralph Droms, and Mohammed
Boucadair for reviewing this document and suggesting changes.

11. Security Considerations

The line identification information inserted by the AN or the edge
router Edge
Router is not protected. This means that this option may be
modified, inserted, or deleted without being detected. In order to
ensure validity of the contents of the line identification Line ID field, the network
between the AN and the edge router Edge Router needs to be trusted.

12. IANA Considerations

This document defines a new IPv6 destination option for carrying line
identification. IANA is requested to assign a has assigned the following new destination
option type in the Destination "Destination Options and Hop-by-Hop Options"
registry maintained at

http://www.iana.org/assignments/ipv6-parameters

<TBA1>
<http://www.iana.org/assignments/ipv6-parameters>:

0x8C Line Identification Option [RFCXXXX] [RFC6788]

The act bits for this option need to be is 10 and the chg bit needs to
be is 0.

This document

Per this document, IANA has also requires allocated the allocation of a following well-known
link-local scope multicast address from the IPv6 "IPv6 Multicast Address
Space
Registry Registry" located at

http://www.iana.org/assignments/ipv6-multicast-addresses/
ipv6-multicast-addresses.xml

<TBA2>
<http://www.iana.org/assignments/ipv6-multicast-addresses/>:

FF02:0:0:0:0:0:0:10 All-BBF-Access-Nodes [RFCXXXX] [RFC6788]

13. References

13.1. Normative References

[RFC1661] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)", STD
51, RFC 1661, July 1994.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, December 1998.

[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, July 2003.

[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005.

[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.

[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.

[TR101] Broadband Forum, "Migration to Ethernet-based DSL
aggregation", <http://www.broadband-forum.org/technical/
download/TR-101.pdf>. <http://www.broadband-forum.org/
technical/download/TR-101.pdf>.

[TR124] Broadband Forum, "Functional Requirements for Broadband
Residential Gateway Devices", <http://
www.broadband-forum.org/technical/download/
TR-124_Issue-2.pdf>.
<http://www.broadband-forum.org/technical/
download/TR-124_Issue-2.pdf>.

[TR156] Broadband Forum, "Using GPON Access in the context of TR-
101", <http://www.broadband-forum.org/technical/download/
TR-156.pdf>.
TR-101", <http://www.broadband-forum.org/
technical/download/TR-156.pdf>.

[TR177] Broadband Forum, "IPv6 in the context of TR-101",
<www.broadband-forum.org/technical/download/TR-177.pdf>.

[X3.4] American National Standards Institute, "American Standard
Code for Information Interchange (ASCII)", Standard X3.4 , X3.4,
1968.

13.2. Informative References

[RFC0020] Cerf, V., "ASCII format for network interchange", RFC 20,
October 1969.

[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.

[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", RFC
3046, January 2001.

[RFC4649] Volz, B., "Dynamic Host Configuration Protocol for IPv6
(DHCPv6) Relay Agent Remote-ID Option", RFC 4649, August
2006.

[RSDA] Dec, W., "IPv6 Router Solicitation Driven Access
Considered Harmful", draft-dec-6man-rs-access-harmful-00
(work Work in progress), Progress, June 2011.

Authors' Addresses

Suresh Krishnan
Ericsson
8400 Blvd Decarie
Town of Mount Royal, Quebec
Canada

Email:

EMail: suresh.krishnan@ericsson.com

Alan Kavanagh
Ericsson
8400 Blvd Decarie
Town of Mount Royal, Quebec
Canada

Email:

EMail: alan.kavanagh@ericsson.com

Balazs Varga
Ericsson
Konyves Kalman krt. 11. B.
1097 Budapest
Hungary

Email:

EMail: balazs.a.varga@ericsson.com

Sven Ooghe
Alcatel-Lucent
Copernicuslaan 50
2018 Antwerp,
Belgium

Phone:
Email:
EMail: sven.ooghe@alcatel-lucent.com

Erik Nordmark
Cisco
510 McCarthy Blvd.
Milpitas, CA, 95035
USA

Phone: +1 408 527 6625
Email:
EMail: nordmark@cisco.com