Internet Engineering Task Force (IETF) J. Brzozowski
Request for Comments: 6853 Comcast Cable Communications
BCP: 180 J. Tremblay
Category: Best Current Practice Videotron G.P.
ISSN: 2070-1721 J. Chen
Time Warner Cable
T. Mrugalski
ISC
February 2013
DHCPv6 Redundancy Deployment Considerations
Abstract
This document provides information for those wishing to use DHCPv6 to
support their deployment of IPv6. In particular, it discusses the
provision of semi-redundant DHCPv6 services.
Status of This Memo
This memo documents an Internet Best Current Practice.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
BCPs is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6853.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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.
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scope and Assumptions . . . . . . . . . . . . . . . . . . . . 2
2.1. Applicability to Prefix Delegation . . . . . . . . . . . . 3
3. Service Provider Deployment . . . . . . . . . . . . . . . . . 3
4. Enterprise Deployment . . . . . . . . . . . . . . . . . . . . 4
5. Protocol Requirements . . . . . . . . . . . . . . . . . . . . 5
5.1. DHCPv6 Servers . . . . . . . . . . . . . . . . . . . . . . 5
5.2. DHCPv6 Relays . . . . . . . . . . . . . . . . . . . . . . 5
5.3. DHCPv6 Clients . . . . . . . . . . . . . . . . . . . . . . 5
6. Deployment Models . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Split Prefixes . . . . . . . . . . . . . . . . . . . . . . 6
6.2. Multiple Unique Prefixes . . . . . . . . . . . . . . . . . 8
6.3. Identical Prefixes . . . . . . . . . . . . . . . . . . . . 10
7. Challenges and Issues . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.1. Normative References . . . . . . . . . . . . . . . . . . . 15
10.2. Informative References . . . . . . . . . . . . . . . . . . 15
1. Introduction
Redundancy and high availability for many components of IPv6
infrastructure are desirable and, in some deployments, mandatory.
Unfortunately, for DHCPv6 there is currently no standards-based
failover or redundancy protocol. An interim solution is to provide
semi-redundant services: this document specifies an architecture by
which this can be achieved.
2. Scope and Assumptions
DHCPv6 redundancy may be useful in a wide range of scenarios.
Although the architecture suggested in this document is able to be
used in a wide range of networks, just two deployment environments
are discussed here: service provider and enterprise network. All
other scenarios may be generalized to one of these two cases.
In the rest of the document, the following assumptions are made with
regards to the existing DHCPv6 infrastructure, regardless of the
environment being considered:
1. At least two DHCPv6 servers provide a service to the same
clients. (The architecture does not limit the number of servers,
and more may be provided if required.)
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2. The existing DHCPv6 servers will not directly communicate or
interact with one another in the assignment of IPv6 addresses and
the provision of configuration information to requesting clients.
3. DHCPv6 clients are instructed to run stateful DHCPv6 to request
at least one IPv6 address. Configuration information and other
options (such as a delegated IPv6 prefix) may also be requested
as part of the stateful DHCPv6 operation.
4. Clients participating in DHCPv6 configuration have to properly
handle the preference option, including the processing of
ADVERTISE messages as required by [RFC3315].
5. A DHCPv6 server failure does not imply a failure of any other
network service or protocol (e.g., TFTP servers). The redundancy
of any additional services configured by means of DHCPv6 are
outside the scope of this document. (For example, a single
DHCPv6 server may configure multiple TFTP servers, with
preference for each TFTP server, as specified in [RFC5970].)
While the techniques described in this document provide some aspects
of redundancy, it should be noted that complete redundancy will not
be available until a DHCPv6 failover protocol is standardized. The
requirements for such a protocol are described in [FAILREQ].
2.1. Applicability to Prefix Delegation
The same approaches discussed in this document can potentially be
applied to prefix delegation (PD) [RFC3633]. One obvious drawback of
using a split prefix model for PD is that use of resources is
doubled. It should be noted that such applicability remains
theoretical and was not investigated thoroughly during work on this
document. As such, the applicability of presented mechanisms to the
prefix delegation is outside of the scope of this document.
3. Service Provider Deployment
The service provider model represents cases where the network and
end-user devices may be administered by separate entities.
The DHCPv6 clients include cable modems, customer gateways or home
routers, and end-user devices: these are collectively referred to as
Customer Premises Equipment (CPE). In some cases hosts may be
configured directly using the service provider DHCPv6 infrastructure;
in others, configuration may be via an intermediate router that is
being configured by the provider DHCPv6 infrastructure. Either way,
the service provider DHCPv6 infrastructure may be semi-redundant.
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In discussing this environment, additional assumptions to those
listed in Section 2 have been made:
1. The service provider edge routers and access routers are IPv6
enabled when required. These routers are, for example, CMTS
(Cable Modem Termination System) for cable or DSLAM/BRAS (Digital
Subscriber Link Access Multiplexer / Broadband Remote Access
Server) for DSL.
2. CPE devices are instructed to perform stateful DHCPv6 to request
at least one IPv6 address, delegated prefix, and/or configuration
information. CPE devices may also be instructed to use stateless
DHCPv6 [RFC3736] to acquire configuration information only, a
situation that assumes the IPv6 address and prefix information
has been acquired using other means.
3. The primary application of this architecture is for native IPv6
services. (Use and applicability to transition mechanisms are
out of scope for this document.)
4. The CPE devices must implement a stateful DHCPv6 client
[RFC3315]. Support for DHCPv6 prefix delegation [RFC3633] or
stateless DHCPv6 [RFC3736] may also be implemented.
4. Enterprise Deployment
The enterprise deployment environment covers cases where end-user
devices are direct consumers of the configuration provided by the
DHCP servers without any intermediate devices (as was the case with
home routers used in the service provider environment). Although
enterprise IPv6 environments quite often use or require DHCPv6 relay
agents, the relays do not influence or process the configuration in
any way and merely act as a transport mechanism.
The additional assumptions made for this model beyond those listed in
Section 2 are:
1. DHCPv6 clients are hosts and are considered end nodes, i.e., they
consume provided configuration and do not use it to provision
other devices. Examples of such clients include desktop
computers, laptops, printers, other typical office equipment, and
some mobile devices.
2. The DHCPv6 clients generally do not require the assignment of an
IPv6 prefix delegation, and as such they typically do not support
DHCPv6 prefix delegation [RFC3633].
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
5. Protocol Requirements
Implementation of the architecture for semi-redundant DHCPv6 services
using existing protocols requires the component DHCPv6 clients,
relays, and servers to have certain capabilities. The following
sections describe the requirements of such devices.
5.1. DHCPv6 Servers
This interim architecture requires the DHCPv6 servers that are
[RFC3315] compliant and support the necessary options. Support for
stateful DHCPv6 and the DHCPv6 preference option [RFC3315] is
essential to the architecture. For deployment scenarios where IPv6
prefix delegation is needed, DHCPv6 servers must support DHCPv6
prefix delegation as defined by [RFC3633]. Furthermore, the DHCPv6
servers must support [RFC3736] if stateless DHCPv6 is used.
5.2. DHCPv6 Relays
DHCPv6 relay agents must be [RFC3315] compliant and must support the
ability to relay DHCPv6 messages to more than one destination.
5.3. DHCPv6 Clients
DHCPv6 clients are required to be compliant with [RFC3315] and
support the necessary options required to support the solution
depending on the mode of operations and desired behavior:
o If prefix delegation is required, DHCPv6 clients must support
DHCPv6 prefix delegation as defined in [RFC3633].
o Clients must support the acquisition of at least one IPv6 address
and configuration information using stateful DHCPv6 as specified
by [RFC3315].
o Stateless DHCPv6 [RFC3736] may also be supported.
o DHCPv6 clients must recognize and adhere to the processing of the
advertised DHCPv6 preference option sent by the DHCPv6 servers.
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
6. Deployment Models
At the time of writing, a standards-based DHCPv6 redundancy protocol
is not available. In the interim solution presented here, existing
DHCPv6 server implementations are used as-is to provide best effort,
semi-redundant DHCPv6 services. The behavior of these services will,
in part, be governed by the configuration of each of the servers.
Various aspects of the DHCPv6 protocol [RFC3315] are used to yield
the desired behavior, although there is no inter-server or inter-
process communication to coordinate DHCPv6 events and/or activities.
The solution does not impact DHCPv4, so DHCP services for both IPv4
and IPv6 may operate simultaneously on the same physical server(s) or
may operate on different ones.
This section defines three semi-redundant models. Although /64
prefixes are used throughout the following sections as examples,
other prefix lengths may be used as well.
6.1. Split Prefixes
In the split prefixes model, each DHCPv6 server is configured with a
unique, non-overlapping pool derived from the /64 prefix deployed for
use within an IPv6 network. For example, distributing an allocated
/64 such as 2001:db8:1:1::/64 between two servers would require that
it be split into two /65 pools, 2001:db8:1:1:0000::/65 and 2001:db8:
1:1:8000::/65.
Both DHCPv6 servers are simultaneously active and operational, and
each allocates IPv6 addresses from the corresponding pools per device
class. The address allocation is governed largely through the use of
the DHCPv6 preference option, so the server with the higher
preference value is always preferred. Additional proprietary
mechanisms can be used to further enforce the favoring of one DHCP
server over another. An example of such a scenario is presented in
Figure 1.
It is important to note that, over time, it is possible that bindings
will be unevenly distributed amongst the DHCPv6 servers, and no one
server will be authoritative for all of them.
As defined in [RFC3315], a DHCPv6 ADVERTISE message with a preference
option of 255 is an indicator to a DHCPv6 client to immediately begin
a client-initiated message exchange by transmitting a REQUEST message
to the server that sent the ADVERTISE. Alternatively, a DHCPv6
ADVERTISE message with no preference option (or one with a value less
Brzozowski, et al. Best Current Practice [Page 6]
RFC 6853 DHCPv6 Redundancy Considerations February 2013
than 255) is an indicator to the client that it must wait for
subsequent ADVERTISE messages before choosing the server to which is
responds, as described in Section 17.1.2 of [RFC3315].
In the event of a DHCPv6 server failure, it is desirable (but not
essential) for a server other than the server that originally
responded to be able to rebind the client's lease. Given the
proposed architecture, the remaining active DHCPv6 server will have a
different address pool configured, making it technically incorrect to
rebind the client in its current state. Ultimately, the rebinding
will fail and the client will acquire a new binding from the pool
configured in the active server.
To reduce the possibility that a client or some other element on the
network will experience a disruption in service or access to relevant
binding data, shorter values for T1, T2, valid, and preferred
lifetimes can be used. The values for the last three can be adjusted
or configured to minimize service disruption. Ideally, setting them
equal (or nearly equal) can be used to trigger a DHCPv6 client to
reacquire the IPv6 address, prefix, and/or configuration information
almost immediately after the rebinding fails. It is important to
note, however, that shorter values will create an additional load on
the DHCPv6 servers.
While using a split prefix configuration model, the dynamic updates
to DNS [RFC2136] can be coordinated to ensure that the DNS is
properly updated with the current binding information. Challenges
arise with regards to the update of the PTR resource record for IPv6
addresses since the DNS information may need to be overwritten in a
failure condition. The use of split prefixes enables the
differentiation of bindings and binding timing to determine which
represents the current state. This becomes particularly important
when DHCPv6 Leasequery [RFC5007] and/or DHCPv6 Bulk Leasequery
[RFC5460] are used to determine lease or binding state.
Finally, a benefit of this scheme is that the use of separate pools
per DHCPv6 server makes failure conditions more obvious and
detectable.
Brzozowski, et al. Best Current Practice [Page 7]
RFC 6853 DHCPv6 Redundancy Considerations February 2013
+----------+ +-----------+
| Client 1 +-\ +--+ Server 1 |
+----------+ \ | +-----------+
\ |
\ |
\ |
+----------+ \ | +-----------+
| Client 2 +--------------+--| Server 2 |
+----------+ / | +-----------+
. / .
. / .
. / .
+----------+ / . +-----------+
| Client N +-/ .--| n+1 Server|
+----------+ +-----------+
Server 1
========
Prefix = 2001:db8:1:1::/64
Pool = 2001:db8:1:1:0000::/65
Preference = 255
Server 2
========
Prefix = 2001:db8:1:1::/64
Pool = 2001:db8:1:1:8000::/65
Preference = 0
Server n+1
==========
Prefix, pool, and preference would
vary based on prefix definition
Figure 1: Split prefixes approach
6.2. Multiple Unique Prefixes
In the multiple prefix model, each DHCPv6 server is configured with a
unique, non-overlapping prefix. A /64 pool equal to the prefix is
configured on each server. For example, the 2001:db8:1:1::/64 pool
would be assigned to a single DHCPv6 server for allocation to clients
equal to its parent prefix 2001:db8:1:1::/64. The second DHCPv6
server could use 2001:db8:1:5::/64 as both pool and prefix. This
would be repeated for each active DHCP server. An example of this
scenario is presented in Figure 2.
Brzozowski, et al. Best Current Practice [Page 8]
RFC 6853 DHCPv6 Redundancy Considerations February 2013
The major difference between the split prefixes approach and the
multiple unique prefixes approach is that the latter does not require
prefixes to be adjacent. In fact, the split prefixes approach can be
considered a special case of the multiple unique prefixes approach.
This approach uses a unique prefix and ultimately a single pool per
DHCPv6 server with the corresponding prefixes configured for use in
the network. The corresponding network infrastructure must in turn
be configured to use multiple prefixes on the interface(s) facing the
DHCPv6 clients. The configuration is similar on all the servers, but
a different prefix and a different preference are used for each
DHCPv6 server.
This approach drastically increases the rate of consumption of IPv6
prefixes and also yields operational and management challenges
related to the underlying network since a significantly higher number
of prefixes need to be configured and routed. It also does not
provide a clean migration path to the desired solution using a
standards-based DHCPv6 redundancy or failover protocol (which, of
course, has yet to be specified).
The use of multiple unique prefixes provides benefits related to
dynamic updates to DNS similar to those referred to in Section 6.1.
The use of multiple unique prefixes enables the differentiation of
bindings and binding timing to determine which represents the current
state. This becomes particularly important when DHCPv6 Leasequery
[RFC5007] and/or DHCPv6 Bulk Leasequery [RFC5460] are used to
determine lease or binding state. The use of separate prefixes and
pools per DHCPv6 server makes failure conditions more obvious and
detectable.
Brzozowski, et al. Best Current Practice [Page 9]
RFC 6853 DHCPv6 Redundancy Considerations February 2013
+----------+ +-----------+
| Client 1 +-\ +--+ Server 1 |
+----------+ \ | +-----------+
\ |
\ |
\ |
+----------+ \ | +-----------+
| Client 2 +--------------+--| Server 2 |
+----------+ / | +-----------+
. / .
. / .
. / .
+----------+ / . +-----------+
| Client N +-/ .--| n+1 Server|
+----------+ +-----------+
Server 1
========
Prefix = 2001:db8:1:1::/64
Pool = 2001:db8:1:1::/64
Preference = 255
Server 2
========
Prefix = 2001:db8:1:5::/64
Pool = 2001:db8:1:5::/64
Preference = 0
Server 3
========
Prefix = 2001:db8:1:f::/64
Pool = 2001:db8:1:f::/64
Preference = [1..254]
Figure 2: Multiple unique prefix approach
6.3. Identical Prefixes
In the identical prefix model, each DHCPv6 server is configured with
the same overlapping prefix and pool deployed for use within an IPv6
network. Distribution between two or more servers, for example,
would require that the same /64 prefix and pool be configured on all
DHCP servers. For instance, the 2001:db8:1:1::/64 pool would be
assigned to all the DHCPv6 servers for allocation to clients derived
from the 2001:db8:1:1::/64 prefix. This would be repeated for each
active DHCP server. An example of such a scenario is presented in
Figure 3.
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
This approach uses the same prefix, length, and pool definition
across multiple DHCPv6 servers. All other configuration parameters
remain the same, with the exception of the DHCPv6 preference. Such
an approach conceivably eases the migration of DHCPv6 services to
fully support a standards-based redundancy or failover protocol once
such solution becomes available. Similar to the split prefix
architecture described above, this approach does not place any
additional addressing requirements on the network infrastructure.
The use of identical prefixes provides no benefit or advantage
related to dynamic DNS updates, support of DHCPv6 Leasequery
[RFC5007] or DHCPv6 Bulk Leasequery [RFC5460]. In this case, all
DHCP servers will use the same prefix and pool configurations making
it less obvious that a failure condition or event has occurred.
Brzozowski, et al. Best Current Practice [Page 11]
RFC 6853 DHCPv6 Redundancy Considerations February 2013
+----------+ +-----------+
| Client 1 +-\ +--+ Server 1 |
+----------+ \ | +-----------+
\ |
\ |
\ |
+----------+ \ | +-----------+
| Client 2 +--------------+--| Server 2 |
+----------+ / | +-----------+
. / .
. / .
. / .
+----------+ / . +-----------+
| Client N +-/ .--| n+1 Server|
+----------+ +-----------+
Server 1
========
Prefix = 2001:db8:1:1::/64
Pool = 2001:db8:1:1::/64
Preference = 255
Server 2
========
Prefix = 2001:db8:1:1::/64
Pool = 2001:db8:1:1::/64
Preference = 0
Server 3
========
Prefix = 2001:db8:1:1::/64
Pool = 2001:db8:1:1::/64
Preference = [1..254]
Figure 3: Identical prefix approach
7. Challenges and Issues
The lack of interaction between DHCPv6 servers introduces a number of
challenges related to the operations of the same service instances in
a production environment. The following areas are of particular
concern:
o In the identical prefixes scenario, both servers must follow the
same address allocation procedure, i.e., they both must use the
same algorithm and the same policy to determine which address is
going to be assigned to a specific client. Otherwise, there is a
distinct chance that each server will assign the same address to
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
two different clients. It is expected that both servers will
receive each incoming REQUEST message. Usually, no special action
is required to achieve this as REQUEST messages are sent to a
multicast address by clients. Relays are expected to forward
incoming client messages to all servers. The client indicates the
chosen server by including its DHCP Unique Identifier (DUID) in
the Server-ID option. The chosen server assigns the address and
other configuration options, while the other server discards the
incoming request. In case of a failure of one server, the other
server will assign the same address by following the same
algorithm and the same policy.
o Interactions with DNS server(s) using dynamic update for the same
address when one or more DHCPv6 servers have become unavailable.
This specifically becomes a challenge when (or if) nodes that were
initially granted a lease:
1. Attempt to renew or rebind the lease originally granted, or
2. Attempt to obtain a new lease
The DHCID resource record [RFC4701] allows identification of the
current owner of the specific DNS data that is the target of an
update [RFC2136]. [RFC4704] specifies how DHCPv6 servers and/or
clients may perform updates. [RFC4703] provides a way to solve
conflicts between clients. Although [RFC4703] deals with most
cases, it is still possible to leave abandoned resource records.
Consider the following scenario: there are two independent
servers, A and B. Server A assigns a lease to a client and
updates the DNS with an AAAA record for the assigned address.
When the client renews, server A is not available and server B
assigns a different lease. The DNS is again updated, so now two
AAAA resource records are present for the client: there is no
indication as to which of the two leases is active. If server A
never recovers, its information may never be removed (although it
should be noted that this case is somewhat similar to that of a
single server crashing and leaving abandoned resource records).
o Interactions with DHCPv6 servers to facilitate the acquisition of
IPv6 lease data by way of the DHCPv6 Leasequery [RFC5007] or
DHCPv6 Bulk Leasequery [RFC5460] protocols when one or more DHCPv6
servers have granted leases to DHCPv6 clients and later became
unavailable. If the lease data is required and the granting
server is unavailable, it will not be possible to obtain any
information about leases granted until one of the following has
taken place:
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
1. The granting DHCPv6 server becomes available with all lease
information restored.
2. The client has renewed or rebound its lease against a
different DHCPv6 server.
It is important to note that any exchange of available leases and
synchronization between DHCPv6 servers is not possible until a
redundancy or failover protocol is standardized or proprietary
solutions become available.
8. Security Considerations
Additional security considerations are created through the use of
this interim architecture beyond what has been cited in Section 23 of
[RFC3315]. In particular, the dynamic DNS update using the models
defined in this document allows for the possibility of not removing
abandoned DNS records even when using the conflict resolution
mechanism defined in [RFC4703]. However, this is no worse than a
case where a single deployed server crashes and its lease database
cannot be recovered.
When using the identical prefixes model, care must be taken to ensure
that all servers use the same lease allocation procedure and are
configured with the same policy. If this guidance is not followed,
there is a risk of assignment of the same lease to two separate
clients. In some cases, that situation can be recovered by using
Duplicate Address Detection (Neighbor Discovery) and the DECLINE
mechanism (DHCPv6).
9. Acknowledgements
The authors would like to thank Bernie Volz, Kim Kinnear, Ralph
Droms, David Hankins, Chuck Anderson, Ted Lemon, Stephen Farrel, Pete
McCann, Robert Sparks, Martin Stiemerling, Brian Haberman, and Barry
Leiba for their input and review.
Special thanks to Stephen Morris for his numerous spelling, grammar
corrections, and proofreading.
This work has been partially supported by Department of Computer
Communications (a division of Gdansk University of Technology) and
the National Centre for Research and Development (Poland) under the
European Regional Development Fund, Grant No. POIG.01.01.02-00-045/
09-00 (Future Internet Engineering Project).
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10. References
10.1. Normative References
[RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)",
RFC 2136, April 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, April 2004.
[RFC4701] Stapp, M., Lemon, T., and A. Gustafsson, "A DNS Resource
Record (RR) for Encoding Dynamic Host Configuration
Protocol (DHCP) Information (DHCID RR)", RFC 4701,
October 2006.
[RFC4703] Stapp, M. and B. Volz, "Resolution of Fully Qualified
Domain Name (FQDN) Conflicts among Dynamic Host
Configuration Protocol (DHCP) Clients", RFC 4703,
October 2006.
[RFC4704] Volz, B., "The Dynamic Host Configuration Protocol for
IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN)
Option", RFC 4704, October 2006.
[RFC5007] Brzozowski, J., Kinnear, K., Volz, B., and S. Zeng,
"DHCPv6 Leasequery", RFC 5007, September 2007.
[RFC5460] Stapp, M., "DHCPv6 Bulk Leasequery", RFC 5460,
February 2009.
[RFC5970] Huth, T., Freimann, J., Zimmer, V., and D. Thaler, "DHCPv6
Options for Network Boot", RFC 5970, September 2010.
10.2. Informative References
[FAILREQ] Mrugalski, T. and K. Kinnear, "DHCPv6 Failover
Requirements", Work in Progress, September 2012.
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RFC 6853 DHCPv6 Redundancy Considerations February 2013
Authors' Addresses
John Jason Brzozowski
Comcast Cable Communications
1306 Goshen Parkway
West Chester, PA 19380
USA
Phone: +1-609-377-6594
EMail: john_brzozowski@cable.comcast.com
Jean-Francois Tremblay
Videotron G.P.
612 Saint-Jacques
Montreal, Quebec H3C 4M8
Canada
EMail: jf@jftremblay.com
Jack Chen
Time Warner Cable
13820 Sunrise Valley Drive
Herndon, VA 20171
USA
EMail: jack.chen@twcable.com
Tomasz Mrugalski
Internet Systems Consortium, Inc.
950 Charter St.
Redwood City, CA 94063
USA
Phone: +1 650 423 1345
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Brzozowski, et al. Best Current Practice [Page 16]