Internet DRAFT - draft-cheng-dhc-distribute-srv6-locator-by-dhcp
draft-cheng-dhc-distribute-srv6-locator-by-dhcp
Dynamic Host Configuration (DHC) W. Cheng
Internet Draft R. Han
Intended status: Standards Track China Mobile
Expires: July 9, 2023 C. Lin
Y. Qiu
New H3C Technologies
January 6, 2023
Distribute SRv6 Locator by DHCP
draft-cheng-dhc-distribute-srv6-locator-by-dhcp-04
Abstract
In SRv6 network, locators need to be assigned to each SRv6 Endpoint,
and segments are created based on locators. This document describes
the method of assigning locators to SRv6 Endpoints through DHCPv6.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
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This Internet-Draft will expire on July 9 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction ................................................ 2
1.1. Requirements Language .................................. 3
2. Terminology ................................................. 3
3. Scenario for Locator......................................... 3
4. DHCPv6 extension ............................................ 5
4.1. Identity Association for SRv6 Locator Option ........... 5
4.2. IA SRv6 Locator Option ................................. 8
5. Process of Assigning Locator ............................... 10
5.1.1. DHCP Client Behavior ............................. 10
5.1.2. DHCP Server Behavior ............................. 11
5.1.3. DHCP Relay Agent Behavior ........................ 12
6. IANA Considerations ........................................ 13
7. Security Considerations .................................... 13
8. References ................................................. 13
8.1. Normative References .................................. 13
Authors' Addresses ............................................ 15
1. Introduction
Segment Routing (SR) allows a headend node to steer a packet flow
along any path. Per-path states of Intermediate nodes are eliminated
thanks to source routing. The headend node steers a flow into an SR
Policy. The packets steered into an SR Policy carry an ordered list
of segments associated with that SR Policy.
When deploying SRv6, each SRv6 endpoint needs to be assigned a
unique IPv6 prefix, that is, locator. As the identity of the
endpoint, the locator could be distributed to other IPv6 nodes in
the SRv6 domain through IGP, so that other IPv6 nodes could learn
the locator route. SRv6 endpoint allocates segments of various
behaviors based on its locator.
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In some specific scenarios, some SRv6 endpoints do not deploy IGP
with other routers. In this case, the locator route cannot be
distributed in the normal way.
This document describes a method of assigning locators to SRv6
Endpoints through DHCPv6. The existing processing flow of DHCPv6 can
be used to simplify the allocation of locators and route
distributing.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
This document leverages the terms defined in [RFC8415] and
[RFC8986]. The reader is assumed to be familiar with this
terminology.
This document introduces the following new terms:
IA_SRV6_LOCATOR: Identity Association for SRv6 Locator, an IA that
carries delegated SRv6 locator prefixes. See Section 4.1 for detail
on the IA_SRV6_LOCATOR option.
3. Scenario for Locator
Telecom provider use IP Metro network and Backbone network to
realize the interconnection between access users in different
regions.
In the IP backbone network, deploy the network PE (PE-N) for access
users in different regions and the cloud PE (PE-C) for the cloud.
CPEs for access users are connected to the local MAN in various
ways. CPEs are responsible for assigning addresses to access users,
so CPEs apply for DHCPv6 PD from DHCPv6 server.DHCPv6 server is
usually enabled on BRAS.
After the DHCPv6 server allocates PD, BRAS will add a network route
corresponding to PD to local routing table and distribute the
network route to the upstream routers.
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In this networking environment, it is expected to deploy end-to-end
SRv6 to realize interconnection between access users, or between
access users and clouds.
For example, for the traffic from host1 to host2, CPE1 should be the
SRv6 headend node and CPE2 should be the SRv6 endpoint node. When
accessing the cloud, CPE should be the SRv6 headend node and vCPE
should be the SRv6 endpoint node.
To deploy SRv6, the CPE should be configured, such as SRv6 locator.
The locator of each CPE uniquely identifies the CPE, and other
network nodes need to be able to learn the locator route. There are
difficulties in achieving these requirements for the following
reasons:
o configuration complexity
In Metro network, the number of CPEs is very large and widely
distributed geographically. Moreover, the mobility requirements of
CPE are relatively high, and the access location of the same CPE
often changes, so the IP address of CPE cannot be fixed.
In order to simplify the deployment procedure, zero touch
provisioning (ZTP) deployment technology is often used when
deploying CPE, such as USB-based deployment. The configuration file
is recorded in the USB flash disk, and CPE reads the corresponding
configuration file to complete the basic configuration. In this way,
the configuration file in the USB flash disk should only contain
general configuration, and the personalized configuration of the
CPE, such as IP address, should be avoided as far as possible.
Usually, the public network side IPv6 address of CPE is applied for
through the stateless address automatic configuration (SLAAC) of ND
or through DHCPv6.
At present, SRv6 locator can only be configured on each CPE through
the controller or CLI, which increases the configuration complexity.
o locator route learning
CPE can be connected to the BRAS of local MAN through various types
of networks, such as leased line, 4/5G network, optical fiber, etc.
Due to the diversity of connections, IGP is usually only enabled
within the MAN, that is, IGP will not be deployed between CPE and
BRAS.
The locator route of CPE could not be distributed to the BRAS node
through IGP, and the static route can only be configured manually on
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the BRAS or the controller. CPE and BRAS often belong to different
administration domains. Configuring routes to CPE on BRAS increases
the cost and workload of communication and coordination.
Metropolitan area network
+---------------------------+
| |
+------+ +------+ | +-----+ +------+ |
|Host1 +-----+ CPE1 +----+--+BRAS1+--------+ CR1 | |
+------+ +------+ | +-----+ +---+--+ |
| | |
+---------------------+-----+
|
+--------+-------------+
| |
| Backbone Network |
| |
+-------+--------+----+
| |
+--------------------+------+ |
| | | |
+------+ +------+ | +-----+ +--+---+ | |
|Host2 +-----+ CPE2 +----+--+BRAS2+--------+ CR2 | | |
+------+ +------+ | +-----+ +------+ | |
+---------------------------+ |
|
+--+-+
,----+vCPE+---.
,-' +----+ `-.
,' `.
( )
`. Cloud ,'
`-. ,-'
`-------------'
Figure 1: Telecom IPv6 Network
To solve these difficulties this document proposes a method to
allocate SRv6 locators to CPE through DHCPv6, and distribute locator
routes by using the workflow of DHCPv6.
4. DHCPv6 extension
4.1. Identity Association for SRv6 Locator Option
The Identify Association for SRv6 Locator (IA_SRV6_LOCATOR) option
is used to carry an IA_SRV6_LOCATOR, the parameters associated with
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the IA_SRV6_LOCATOR, and the SRv6 locator associated with the
IA_SRV6_LOCATOR.
The format of the IA_SRV6_LOCATOR option is:
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_IA_SRV6_LOCATOR | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. IA_SRV6_LOCATOR-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Identify Association for SRv6 Locator Option Format
Where:
- Option-code: OPTION_IA_SRV6_LOCATOR (TBD).
- Option-len: 12 + length of IA_SRV6_LOCATOR-options field.
- IAID: The unique identifier for this IA_SRV6_LOCATOR. The IAID
must be unique among the identifiers for all of this client's
IA_SRV6_LOCATORs. The number space for IA_SRV6_LOCATOR IAIDs is
separate from the number space for other IA option types (i.e.,
IA_TA, IA_NA and IA_PD). A 4-octet field containing an unsigned
integer.
- T1: The time interval after which the client should contact the
server from which the SRv6 locator in the IA_SRV6_LOCATOR were
obtained to extend the lifetimes of the SRv6 locators to the
IA_SRV6_LOCATOR; T1 is a time duration relative to the message
reception time expressed in units of seconds. A 4-octet field
containing an unsigned integer.
- T2: The time interval after which the client should contact any
available server to extend the lifetimes of the SRv6 locators
assigned to the IA_SRV6_LOCATOR; T2 is a time duration relative to
the message reception time expressed in units of seconds. A 4-octet
field containing an unsigned integer.
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- IA_SRV6_LOCATOR-options: Options associated with this
IA_SRV6_LOCATOR. A variable-length field (12 octets less than the
value in the Option-len field).
The IA_SRV6_LOCATOR-options field encapsulates those options that
are specific to this IA_SRV6_LOCATOR. For example, all of the IA
SRv6 Locator options (see Section 4.2) carrying the SRv6 locators
associated with this IA_SRV6_LOCATOR are in the IA_SRV6_LOCATOR-
options field.
An IA_SRV6_LOCATOR option may only appear in the options area of a
DHCP message. A DHCP message may contain multiple IA_SRV6_LOCATOR
options (though each must have a unique IAID).
The status of any operations involving this IA_SRV6_LOCATOR is
indicated in a Status Code option (see Section 21.13 of [RFC8415])
in the IA_SRV6_LOCATOR-options field.
Note that an IA_SRV6_LOCATOR has no explicit "lifetime" or "lease
length" of its own. When the valid lifetimes of all of the SRv6
locators in an IA_SRV6_LOCATOR have expired, the IA_SRV6_LOCATOR can
be considered as having expired. T1 and T2 fields are included to
give the server explicit control over when a client should contact
the server about a specific IA_SRV6_LOCATOR.
In a message sent by a client to a server, the T1 and T2 fields
SHOULD be set to 0. The server MUST ignore any values in these
fields in messages received from a client.
In a message sent by a server to a client, the client MUST use the
values in the T1 and T2 fields for the T1 and T2 timers, unless
values in those fields are 0. The values in the T1 and T2 fields
are the number of seconds until T1 and T2.
The server selects the T1 and T2 times to allow the client to extend
the lifetimes of any SRv6 locators in the IA_SRV6_LOCATOR before the
lifetimes expire, even if the server is unavailable for some short
period of time. Recommended values for T1 and T2 are 0.5 and 0.8
times the shortest preferred lifetime of the SRv6 locators in the
IA_SRV6_LOCATOR that the server is willing to extend, respectively.
If the time at which the SRv6 locators in an IA_SRV6_LOCATOR are to
be renewed is to be left to the discretion of the client, the server
sets T1 and T2 to 0. The client MUST follow the rules defined in
Section 14.2 of [RFC8415].
If a client receives an IA_SRV6_LOCATOR with T1 greater than T2 and
both T1 and T2 are greater than 0, the client discards the
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IA_SRV6_LOCATOR option and processes the remainder of the message as
though the server had not included the IA_SRV6_LOCATOR option.
If the device does not support IA_SRV6_LOCATOR, this IA_SRV6_LOCATOR
option should be ignored.
4.2. IA SRv6 Locator Option
The IA SRv6 Locator option is used to specify a SRv6 locator
associated with an IA_SRV6_LOCATOR. The IA SRv6 Locator option must
be encapsulated in the IA_SRV6_LOCATOR-options field of an
IA_SRV6_LOCATOR option (see Section 4.1). The terms Locator Block
and Locator Node correspond to the B and N parts, respectively, of
the SRv6 Locator that is defined in Section 3.1 of [RFC8986].
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_IALOCATOR | Option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LOC-len | Func-len | Args-len | LB-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| |
| SRv6-Locator |
| (16 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. IALocator-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: IA SRv6 Locator Option Format
Where:
- Option-code: OPTION_IALOCATOR (TBD).
- Option-len: 28 + length of IALocator-options field.
- Preferred-lifetime: The preferred lifetime for the SRv6 locator
in the option, expressed in units of seconds. A value of 0xffffffff
represents "infinity" (see Section 7.7 of [RFC8415]). A 4-octet
field containing an unsigned integer.
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- Valid-lifetime: The valid lifetime for the SRv6 locator in the
option, expressed in units of seconds. A value of 0xffffffff
represents "infinity". A 4-octet field containing an unsigned
integer.
- LOC-len: The locator (LOC) length of SRv6 SID in bits. A 1-octet
unsigned integer.
- Func-len: The function (FUNCT) length of SRv6 SID in bits. A 1-
octet unsigned integer.
- Args-len: The arguments (ARG) length of SRv6 SID in bits. A 1-
octet unsigned integer.
- LB-len: The Locator Block length of SRv6 SID in bits. A 1-octet
unsigned integer.
- SRv6-locator: A SRv6 locator prefix. A 16-octet field.
- IALocator-options: Options associated with this SRv6 locator. A
variable-length field (28 octets less than the value in the Option-
len field).
For compressible SID, the length of Locator Node is LOC-len minus
LB-len.
In a message sent by a client to a server, the preferred-lifetime
and valid-lifetime fields SHOULD be set to 0. The server MUST ignore
any received values in these lifetime fields.
The client SHOULD NOT send an IA SRv6 Locator option with 0 in the
"LOC-len" field (and an unspecified value (::) in the "SRv6-Locator"
field). A client MAY send a non-zero value in the "LOC-len" field
and the unspecified value (::) in the "SRv6-Locator" field to
indicate a preference for the size of the SRv6 locator to be
delegated. The LOC-len hint of IA_SRV6_LOCATOR is the same as
prefix-length hint of IA_PD. For further details on LOC-len hints,
see [RFC8168].
The client MUST discard any SRv6 locators for which the preferred
lifetime is greater than the valid lifetime.
The values in the preferred-lifetime and valid-lifetime fields are
the number of seconds remaining in each lifetime. For more details
on how these values are used to assign locators, see section
18.2.10.1 of [RFC8415], which is the same as prefix delegation.
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As per Section 7.7 of [RFC8415], the value of 0xffffffff for the
preferred lifetime or the valid lifetime is taken to mean "infinity"
and should be used carefully.
An IA SRv6 Locator option may appear only in an IA_SRV6_LOCATOR
option. More than one IA SRv6 Locator option can appear in a single
IA_SRV6_LOCATOR option.
The status of any operations involving this IA SRv6 Locator option
is indicated in a Status Code option (see Section 21.13 of
[RFC8415]) in the IALocator-options field.
5. Process of Assigning Locator
This document assumes that a client SHOULD use a single transaction
for all of the IA options required on an interface. This simplifies
the client implementation and reduces the potential number of
transactions required (for the background on this design choice,
refer to Section 4 of [RFC7550]). If a client requests multiple IA
option types, follow [RFC7550].
5.1.1. DHCP Client Behavior
A client uses the Solicit message to discover DHCPv6 servers
configured to assign leases or return other configuration parameters
on the link to which the client is attached.
A client uses Request, Renew, Rebind, Release, and Decline messages
during the normal lifecycle of addresses and delegated prefixes.
The process of applying for SRv6 locator is the same as that of
applying for PD. When applying for SRv6 locator, the DHCPv6 client
sends a request message carrying the IA_SRV6_LOCATOR option to the
DHCPv6 server.
Upon the receipt of a valid reply message with IA_SRV6_LOCATOR
option in response to a Solicit with a Rapid Commit option, Request,
Confirm, Renew, or Rebind message, the client SHOULD process the
Reply message according to the requirements of Section 18.2 of
[RFC8415], and configure the delegated locator in the client device
automatically.
When the client uses a delegated locator prefix to configure SRv6
locator locally, the preferred and valid lifetimes of those locators
MUST be no longer than the remaining preferred and valid lifetimes
respectively for the delegated SRv6 locator at any time.
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To extend the preferred and valid lifetimes for the leases assigned
to the IAs and obtain new delegated SRv6 locators for IAs, the
client sends a Renew/Rebind message to the server with
IA_SRV6_LOCATOR option. When the valid lifetime of the SRv6 locator
expires, or the new lifetime replied by the server is 0, delete the
corresponding SRv6 locator.
If the client no longer uses the delegated SRv6 locator, the client
can actively send a Release message to notify the server to reclaim
locator prefixes and delete the corresponding SRv6 locator. The
client MUST include options containing the IAs for the locators it
is releasing in the IA_SRV6_LOCATOR-options of IA_SRV6_LOCATOR
option.
A client can explicitly request multiple SRv6 Locator prefixes by
sending multiple IA_SRV6_LOCATOR options. A client can send multiple
IA_SRV6_LOCATOR options in its initial transmissions.
Alternatively, it can send an extra Request message with additional
new IA_SRV6_LOCATOR options (or include them in a Renew message).
In principle, DHCP allows a client to request new Locator prefixes
to be delegated by sending additional new IA_SRV6_LOCATOR options.
However, a typical operator usually prefers to delegate a single,
larger prefix. In most deployments, it is recommended that the
client request a larger Locator prefix in its initial transmissions
rather than request additional Locator prefixes later on.
5.1.2. DHCP Server Behavior
As described in [RFC8415], when the server receives a valid Request
message or a valid Solicit message with a Rapid Commit option, the
server creates the bindings for that client according to the
server's policy and configuration information and records the IAs
and other information requested by the client.
The DHCPv6 server treats the locator as the prefix of prefix pool,
which is similar to the prefix allocation process. Upon the receipt
of the IA_SRV6_LOCATOR option, the server searches locator prefix
pool and allocates appropriate locators for the client.
If there is an assignable locator prefix, the server records the
locator binding entry and encapsulates the locator information into
the DHCPv6 Reply message. The IA_SRV6_LOCATOR option fills with the
locator prefix information assigned to the client. The IA SRv6
Locator option populates the SRv6 locator length, function length,
arguments length and Locator Block length of SRv6 SID specified by
the DHCPv6 server.
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For the scenario described in Section 2 where the BRAS device acts
as a DHCPv6 server, after the locator is successfully delegated, the
server generates a locator subnet route locally, and the outgoing
interface of the route is the access interface connecting the
client.
Upon receiving the Release message from the client or when the
locator lease expires, the server reclaims the locator prefix
resource and deletes the locator binding entry. If the BRAS device
acts as a DHCPv6 server, the server also SHOULD delete the
corresponding locator subnet route locally.
For any IA_SRV6_LOCATOR option in the request message to which the
server cannot assign any delegated SRv6 locator prefixes, the server
MUST return the IA_SRV6_LOCATOR option in the Reply message with no
prefixes in the IA_SRV6_LOCATOR and with a Status Code option
containing status code NoPrefixAvail in the IA_SRV6_LOCATOR.
After receiving a DHCP message with multiple IA_SRV6_LOCATOR options
at the same time, whether the server can assign multiple SRv6
Locator prefixes to the client depends on the server policy, which
is out of scope for this document.
5.1.3. DHCP Relay Agent Behavior
For the scenario described in Section 2, if an external DHCPv6
server is deployed to allocate locators, the DHCPv6 relay agent
service needs to be enabled on the layer 3 network nodes close to
CPE. As shown in the figure below, the DHCP relay function is
enabled on the router directly connected to CPE.
DHCP Relay
+------+ +------+ +------+ +-----+
| Host +-----+ CPE +-------+Router+------+ BRAS|
+------+ +------+ +------+ +--+--+
|
|
+------+-----+
| Backbone |
| Network |
+------------+
Figure 4: CPE accessed through DHCP relay
When the first hop DHCPv6 relay agent device connected to the DHCPv6
PD client receives DHCPv6 Relay-reply messages, it extracts the
IA_SRV6_LOCATOR option from the Relay Message option, and obtains
the locator delegated by the DHCPv6 server according to IA SRv6
Locator option. The first DHCPv6 relay agent needs to record the
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locator delegated by the DHCPv6 server, including locator
information, lifetime, etc. and generates locator route locally. The
outgoing interface of the route is the access interface connecting
the client.
After receiving the DHCPv6 message releasing the locator prefix from
the client or the valid lifetime of Locator prefix expires, the
first DHCPv6 relay agent device SHOULD delete the locator route
locally.
6. IANA Considerations
IANA is kindly requested to assign new values for
OPTION_IA_SRV6_LOCATOR (TBD) and OPTION_IALOCATOR (TBD) and add the
values to the DHCPv6 Option Codes registry maintained at
http://www.iana.org/assignments/dhcpv6-parameters.
+=======+========================+========+===========+===========+
| Value | Description | Client | Singleton | Reference |
| | | ORO | Option | |
+=======+========================+========+===========+===========+
| TBA1 | OPTION_IA_SRV6_LOCATOR | NO | No | [ This |
| | | | | Document ]|
+-------+------------------------+--------+-----------+-----------+
| TBA2 | OPTION_IALOCATOR | NO | No | [ This |
| | | | | Document ]|
+-------+------------------------+--------+-----------+-----------+
Table 1
7. Security Considerations
See [RFC8415] for the DHCPv6 security considerations.
8. References
8.1. Normative References
[RFC7550] Troan, O., Volz, B., Siodelski, M., "Issues and
Recommendations with Multiple Stateful DHCPv6 Options",
RFC 7550, DOI 10.17487/RFC7550, May 2015,
<https://www.rfc-editor.org/info/rfc7550>.
[RFC8168] Li, T., Liu, C., Cui, Y., "DHCPv6 Prefix-Length Hint
Issues", RFC 8168, DOI 10.17487/RFC8168, May 2017,
<https://www.rfc-editor.org/info/rfc8168>.
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[RFC8415] Mrugalski, T., Siodelski, M ., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and Winters, T.,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986, DOI
10.17487/RFC8986, February 2021, <https://www.rfc-
editor.org/info/rfc8986>.
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Authors' Addresses
Weiqiang Cheng
China Mobile
Email: chengweiqiang@chinamobile.com
Ruibo Han
China Mobile
Email: hanruibo@chinamobile.com
Changwang Lin
New H3C Technologies
Email: linchangwang.04414@h3c.com
Yuanxiang Qiu
New H3C Technologies
Email: qiuyuanxiang@h3c.com
Cheng, et al. Expires July, 2023 [Page 15]
