dhc Working Group Kim Kinnear
Internet Draft Richard Johnson
Intended Status: Standards Track Mark Stapp
Expires: August 22, 2008 Jay Kumarasamy
Cisco Systems
February 22, 2008
Virtual Subnet Selection Options for DHCPv4 and DHCPv6
<draft-ietf-dhc-vpn-option-08.txt>
Status of this Memo
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Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract
This memo defines a Virtual Subnet Selection (VSS) option for DHCPv4
and DHCPv6, and a DHCPv4 relay-agent-information sub-option. These
are intended for use by DHCP clients, relay agents, and proxy clients
in situations where VSS information needs to be passed to the DHCP
server for proper address or prefix allocation to take place.
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For the DHCPv4 option and relay-agent-information sub-option, this
memo documents existing usage as per RFC 3942.
Table of Contents
1. Introduction................................................. 2
2. Terminology.................................................. 3
3. Virtual Subnet Selection Option and Sub-Option Definitions... 4
3.1. DHCPv4 Virtual Subnet Selection Option..................... 5
3.2. DHCPv4 Virtual Subnet Selection Sub-Option................. 5
3.3. DHCPv6 Virtual Subnet Selection Option..................... 5
3.4. Virtual Subnet Selection Type and Information.............. 6
4. Relay Agent Behavior......................................... 7
4.1. VPN assignment by the DHCP server.......................... 8
4.2. DHCP Leasequery............................................ 9
5. Client Behavior.............................................. 9
6. Server Behavior.............................................. 10
6.1. Returning the DHCPv4 or DHCPv6 Option...................... 11
6.2. Returning the DHCPv4 Sub-Option............................ 11
6.3. Making sense of conflicting VSS information................ 12
7. Security..................................................... 12
8. IANA Considerations.......................................... 13
9. Acknowledgments.............................................. 14
10. Normative References........................................ 14
11. Informative References...................................... 14
12. Authors' Addresses.......................................... 15
13. Full Copyright Statement.................................... 16
14. Intellectual Property....................................... 16
15. Acknowledgment.............................................. 17
1. Introduction
There is a growing use of Virtual Private Network (VPN)
configurations. The growth comes from many areas; individual client
systems needing to appear to be on the home corporate network even
when traveling, ISPs providing extranet connectivity for customer
companies, etc. In some of these cases there is a need for the DHCP
server to know the VPN (hereafter called a "Virtual Subnet Selector"
or "VSS") from which an address, and other resources, should be
allocated.
This memo defines a Virtual Subnet Selection (VSS) option for DHCPv4
and DHCPv6, and a DHCPv4 relay-agent-information sub-option. These
are intended for use by DHCP clients, relay agents, and proxy clients
in situations where VSS information needs to be passed to the DHCP
server for proper address or prefix allocation to take place. If the
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receiving DHCP server understands the VSS option or sub-option, this
information may be used in conjunction with other information in
determining the subnet on which to select an address as well as other
information such as DNS server, default router, etc.
If the allocation is being done through a DHCPv4 relay, then the
relay sub-option defined here should be included. In some cases,
however an IP address is being sought by a DHCPv4 proxy on behalf of
a client (which may be assigned the address via a different
protocol). In this case, there is a need to include VSS information
relating to the client as a DHCPv4 option.
If the allocation is being done through a DHCPv6 relay, then the
DHCPv6 VSS option defined in this document should be included in the
Relay-forward and Relay-reply message going between the DHCPv6 relay
and server. In some cases, addresses or prefixes are being sought
for by a DHCPv6 proxy on behalf of a client. In this case, there is
a need for the client itself to supply the VSS information using the
DHCPv6 VSS option in the messages that it sends to the DHCPv6 server.
In the remaining text of this document, when a DHCPv6 address is
indicated the same information applies to DHCPv6 Prefix Delegation
[RFC 3633] as well.
2. Terminology
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 RFC 2119 [RFC 2119].
This document uses the following terms:
o "DHCP client"
A DHCP client is a host using DHCP to obtain configuration
parameters such as a network address.
o "DHCP relay agent"
A DHCP relay agent is a third-party agent that transfers BOOTP
and DHCP messages between clients and servers residing on
different subnets, per [RFC 951] and [RFC 1542].
o "DHCP server"
A DHCP server is a host that returns configuration parameters to
DHCP clients.
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o "DHCPv4 option"
An option or used to implement a capability defined by the
DHCPv4 RFCs [RFC 2131][RFC 2132]. These options have one octet
code and size bytes.
o "DHCPv4 sub-option"
As used in this document, a DHCPv4 sub-option refers to a sub-
option of the relay-agent-information option [RFC 3046]. These
sub-options have one octet code and size bytes.
o "DHCPv6 option"
An option used to implement a capability defined by the DHCPv6
RFC [RFC 3315]. These options have two octet code and size
bytes.
o "downstream"
Downstream is the direction from the access concentrator towards
the subscriber.
o "upstream"
Upstream is the direction from the subscriber towards the access
concentrator.
o "VSS information"
Information about a VPN necessary to allocate an address to a
DHCP client on that VPN and necessary to forward a DHCP reply
packet to a DHCP client on that VPN.
o "VPN"
Virtual private network. A network which appears to the client
to be a private network.
o "VPN Identifier"
The VPN-ID is defined by [RFC 2685] to be a sequence of 7
octets.
3. Virtual Subnet Selection Option and Sub-Option Definitions
The Virtual Subnet Selection options and sub-option contains a
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generalized way to specify the VSS information about a VPN. There
are two options and one sub-option defined in this section. The
actual VSS information is identical in each.
3.1. DHCPv4 Virtual Subnet Selection Option
The format of the 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Length | Type | VSS Info ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code The option code (221).
Length The option length, minimum 1 octets.
Type and VSS Information -- see Section 3.4
3.2. DHCPv4 Virtual Subnet Selection Sub-Option
This is a sub-option of the relay-agent-information option [RFC
3046]. The format of the sub-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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Length | Type | VSS Info. ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code The sub-option code (151).
Length The option length, minimum 1 octets.
Type and VSS Information -- see Section 3.4
3.3. DHCPv6 Virtual Subnet Selection Option
The format of the DHCPv6 Virtual Subnet Selection option is shown
below. This option may be included by a client or relay-agent (or
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both).
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_VSS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | VSS Information ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_VSS (TBD).
option-len The number of octets in the option, minimum 1.
Type and VSS Information -- see Section 3.4
3.4. Virtual Subnet Selection Type and Information
All of the (sub)options defined above carry identical payloads,
consisting of a type and additional VSS information as follows:
Type VSS Information format:
0 NVT ASCII VPN identifier
1 RFC2685 VPN-ID
2-254 Not Allowed
255 Global, default VPN.
o Type 0 -- NVT ASCII VPN identifier
Indicates that the VSS information consists of a NVT ASCII string.
It MUST NOT be terminated with a zero byte.
o Type 1 -- RFC2685 VPN-ID
Indicates that the VSS information consists of an RFC2685 VPN-ID
[RFC 2685], which is defined to be 7 octets in length.
o Type 255 -- Global, default VPN
Indicates that there is no explicit, non-default VSS information
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but rather that this option references the normal, global, default
address space. In this case, there MUST NOT be any VSS Information
and the length of the VSS option MUST be 1.
All other values of the Type field are invalid as of this memo and a
VSS option with a Type field containing any value other than zero
(0), one (1), or 255 SHOULD be ignored.
4. Relay Agent Behavior
A relay agent which receives a DHCP request from a DHCP client on a
VPN should include Virtual Subnet Selection information in the DHCP
packet prior to forwarding the packet on to the DHCP server.
A DHCPv4 relay agent SHOULD include a DHCPv4 VSS sub-option in a
relay-agent-information option [RFC 3046], while a DHCPv6 relay agent
SHOULD include a DHCPv6 VSS option in the Relay-forward message.
The value placed in the Virtual Subnet Selection sub-option or option
SHOULD be sufficient for the relay agent to properly route any DHCP
reply packet returned from the DHCP server to the DHCP client for
which it is destined.
Since this option or sub-option is placed in the packet in order to
change the VPN on which an IP address is allocated for a particular
DHCP client, one presumes that an allocation on that VPN is necessary
for correct operation. If this presumption is correct, then a relay
agent which places this option in a packet and doesn't receive it (or
receives a different value than that sent to the server) in the
returning packet should drop the packet since the IP address that was
allocated will not be in the correct VPN. If an IP address that is
not on the requested VPN is not required, then the relay agent is
free to accept the IP address that is not on the VPN that was
requested.
The converse, however, is more complicated. In the DHCPv6 case, the
appearance of the option in the Rely-reply packet does indeed
indicate that the DHCPv6 server understood and acted upon the
contents of the VSS option in the Relay-forward packet. In the
DHCPv4 case, however, the appearance of the sub-option in the relay-
agent-information option received by the relay agent does not
necessarily indicate that the DHCPv4 server even understood, let
alone acted correctly upon, the VSS sub-option that it received.
The reason is that [RFC 3046] specifies that a DHCPv4 server which
supports the relay-agent-information option SHALL copy all sub-
options received in a relay-agent-information option into any
outgoing relay-agent-information option. Because of these
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requirements, even a DHCPv4 server which doesn't implement support
for Virtual Subnet Selection sub-option will almost certainly copy it
into the outgoing relay-agent-information option. This means that
the appearance of the Virtual Subnet Selection sub-option in a
relay-agent-information option doesn't indicate support for the
Virtual Subnet Selection sub-option.
There are only two pieces of information which can be determined from
the appearance or lack of appearance of the DHCPv4 Virtual Subnet
Selection sub-option in a relay-agent-information option received by
a relay agent from a DHCPv4 server. First, if the Virtual Subnet
Selection sub-option does not appear, then the server was able to
support this sub-option but chose not to do so. Second, if the
Virtual Subnet Selection sub-option appears and has a different value
than the one originally included in the relay-agent-information
option, then the DHCP server was able to support this sub-option and
allocated an address using different VSS information than was
originally provided by the relay agent.
Thus, if a DHCPv4 relay agent has a requirement to determine if the
address allocated by a DHCPv4 server is on a particular VPN, it must
use some other approach than the appearance of the VSS sub-option in
the reply packet to make this determination.
This document does not create a requirement that a relay agent
remember the contents of a VSS DHCPv4 sub-option or VSS DHCPv6 option
sent to a DHCP server. In many cases, the relay agent may simply use
the value of the VSS returned by the DHCP server to forward the
response to the DHCP client. If the VSS information, the IP address
allocated, and the VPN capabilities of the relay agent all
interoperate correctly, then the DHCP client will receive a working
IP address. Alternatively, if any of these items don't interoperate
with the others, the DHCP client will not receive a working address.
Note that in some environments a relay agent may choose to always
place a VSS option or sub-option into packets and messages that it
forwards in order to forestall any attempt by a downstream relay
agent or client to specify VSS information. In this case, a type
field of 255 is used to denote the global, default VPN. When the
type field of 255 is used, there MUST NOT be any additional VSS
Information in the VSS option.
4.1. VPN assignment by the DHCP server
In some cases, a DHCP server may use the Virtual Subnet Selection
sub-option or option to inform a relay agent that a particular DHCP
client is associated with a particular VPN. It does this by sending
the Virtual Subnet Selection sub-option or option with the
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appropriate information to the relay agent in the relay-agent-
information option for DHCPv4 or the Relay-reply message in DHCPv6.
If the relay agent is unable to honor the DHCP server's requirement
to place the DHCP client into that VPN it MUST drop the packet and
not send it to the DHCP client.
4.2. DHCP Leasequery
Sometimes a relay-agent needs to submit a DHCP Leasequery [RFC 4388]
[RFC 5007] packet to the DHCP server in order to recover information
about existing DHCP allocated IP addresses on other than the normal,
global VPN. In the context of a DHCP Leasequery the relay agent is a
direct client of the DHCP server and is not relaying a packet for
another DHCP client. Thus, the instructions in Section 5 on Client
Behavior should be followed to include the necessary VSS information.
5. Client Behavior
A DHCPv4 or DHCPv6 client will employ the VSS option to communicate
VSS information to their respective servers. This information MUST
be included in every message concerning any IP address on a different
VPN than the global or default VPN. A DHCPv4 client will place the
DHCPv4 VSS option in its packets, and a DHCPv6 client will place the
DHCPv6 VSS option in its messages.
A DHCPv6 client that needs to place a VSS option into a DHCPv6
message SHOULD place a single VSS option into the DHCPv6 message at
the same level as the Client Identifier option. A DHCPv6 client MUST
NOT include different VSS options in the same DHCPv6 message.
Note that, as mentioned in Section 1, throughout this document when a
DHCPv6 address is indicated the same information applies to DHCPv6
Prefix Delegation [RFC 3633] as well.
Since this option is placed in the packet in order to change the VPN
on which an IP address is allocated for a particular DHCP client, one
presumes that an allocation on that VPN is necessary for correct
operation. If this presumption is correct, then a client which
places this option in a packet and doesn't receive it or receives a
different value in the returning packet should drop the packet since
the IP address that was allocated will not be in the correct VPN. If
an IP address that is not on the requested VPN is not required, then
the client is free to accept the IP address that is not on the VPN
that the was requested.
Client's should be aware that some DHCP servers will return a VSS
option with different values than that which was sent in. In
addition, a client may receive a response from a DHCP server with a
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VSS option when none was sent in by the Client.
Note that when sending a DHCP Leasequery request, a relay agent is
acting as a DHCP client and so it should include the respective
DHCPv4 or DHCPv6 VSS option in its DHCPv4 or DHCPv6 Leasequery packet
if the DHCP Leasequery request is generated for other than the
default, global VPN. It should not include a DHCPv4 sub-option in
this case.
6. Server Behavior
A DHCP server receiving the VSS option or sub-option SHOULD allocate
an IP address (or use the VSS information to access an already
allocated IP address) from the VPN specified by the included VSS
information.
In the case where the type field of the VSS option or sub-option is
255, the VSS option denotes the global, default VPN. In this case,
there is no explicit VSS information beyond the type field.
This document does not prescribe any particular address allocation
policy. A DHCP server may choose to attempt to allocate an address
using the VSS information and, if this is impossible, to not allocate
an address. Alternatively, a DHCP server may choose to attempt
address allocation based on the VSS information and, if that is not
possible, it may fall back to allocating an address on the global or
default VPN. This, of course, is also the apparent behavior of any
DHCP server which doesn't implement support for the VSS option and
sub-option. Thus, DHCP clients and relay agents SHOULD be prepared
for either of these alternatives.
In some cases, a DHCP server may use the Virtual Subnet Selection
sub-option or option to inform a relay agent that a particular DHCP
client is associated with a particular VPN. It does this by sending
the Virtual Subnet Selection sub-option or option with the
appropriate information to the relay agent in the relay-agent-
information option for DHCPv4 or the Relay-reply message in DHCPv6.
In a similar manner, a DHCP server may use the Virtual Subnet
Selection option to inform a DHCP client that the address (or
addresses) it allocated for the client is on a particular VPN.
In either case above, care should be taken to ensure that a client or
relay agent receiving a reply containing a VSS option will correctly
understand the VSS option. Otherwise, the client or relay agent will
end up using the address as though it were a global address.
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6.1. Returning the DHCPv4 or DHCPv6 Option
DHCPv4 or DHCPv6 servers receiving a VSS option (for sub-option
processing, see below) MUST return an instance of this option in the
reply packet or message if the server successfully uses this option
to allocate an IP address, and it MUST NOT include an instance of
this option if the server was unable to or not configured to support
the requested VPN.
If they echo the option (based on the criteria above), servers SHOULD
return the an exact copy of the option unless they desire to change
the VPN on which a client was configured.
6.2. Returning the DHCPv4 Sub-Option
The case of the DHCPv4 sub-option is a bit more complicated. Note
that [RFC 3046] specifies that a DHCPv4 server which supports the
relay-agent-information option SHALL copy all sub-options received in
a relay-agent-information option into any outgoing relay-agent-
information option. Thus, the default behavior for any DHCPv4 server
is to return any VSS sub-option received to the relay agent whether
or not the DHCPv4 server understand the VSS sub-option. A server
which implements the VSS sub-option MUST include the VSS sub-option
in the relay-agent-information option in the reply packet if it
successfully acted upon the VSS information in the incoming VSS sub-
option.
Moreover, if a server uses different VSS information to allocate an
IP address than it receives in a particular DHCPv4 sub-option, it
MUST include that alternative VSS information in a sub-option that it
returns to the DHCPv4 relay agent.
If a DHCPv4 server supports this sub-option and for some reason
(perhaps administrative control) does not honor this sub-option from
the request then it MUST NOT echo this sub-option in the outgoing
relay-agent-information option.
Note that the appearance of the VSS sub-option in a reply packet from
a DHCPv4 server to a relay-agent does not communicate any useful
information about whether or not the server used the VSS sub-option
in its processing. However, the absence of a VSS sub-option in a
reply from a DHCPv4 server when a VSS sub-option was included in a
request to the DHCPv4 server is significant, and means that the
server did not use the VSS information present in the sub-option in
its processing.
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6.3. Making sense of conflicting VSS information
It is possible for a DHCPv4 server to receive both a VSS option and a
VSS sub-option in the same packet. Likewise, a DHCPv6 server can
receive multiple VSS options in nested Relay-forward messages as well
as in the client message itself. In either of these cases, the VSS
information from the relay agent closest to the DHCP server SHOULD be
used in preference to all other VSS information received. In the
DHCPv4 case, this means that the VSS sub-option takes precedence over
the VSS option, and in the DHCPv6 case, this means that the VSS
option from the outer-most Relay-forward message in which a VSS
option appears takes precedence.
The reasoning behind this approach is that the relay-agent closer to
the DHCP server is almost certainly more trusted than the DHCP client
or more distant relay agents, and therefore information in the
relay-agent-information option or the Relay-forward message is more
likely to be correct.
In these situations where multiple VSS option or sub-options appear
in the incoming packet or message, when constructing the response to
be sent to the DHCP client or relay agent, all existing VSS options
or sub-options MUST be replicated in the appropriate places in the
response and MUST contain the VSS information that was used by the
DHCP server to allocate the IP address.
7. Security
Message authentication in DHCPv4 for intradomain use where the out-
of-band exchange of a shared secret is feasible is defined in [RFC
3118]. Potential exposures to attack are discussed in section 7 of
the DHCP protocol specification in [RFC 2131].
Implementations should consider using the DHCPv4 Authentication
option [RFC 3118] to protect DHCPv4 client access in order to provide
a higher level of security if it is deemed necessary in their
environment.
Message authentication in DHCPv4 relay agents as defined in
[RFC 4030] should be considered for DHCPv4 relay agents employing
this sub-option. Potential exposures to attack are discussed in
section 7 of the DHCP protocol specification in [RFC 2131].
For DHCPv6 use of the VSS option, the "Security Considerations"
section of [RFC 3315] details the general threats to DHCPv6, and thus
to messages using the VSS option. The "Authentication of DHCP
Messages" section of [RFC 3315] describes securing communication
between relay agents and servers, as well as clients and servers.
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The VSS option could be used by a client in order to obtain an IP
address from a VPN other than the one where it should. This option
would allow a client to perform a more complete address-pool
exhaustion attack since the client would no longer be restricted to
attacking address-pools on just its local subnet.
A DHCP server that implements these options and sub-option should be
aware of this possibility and use whatever techniques that can be
devised to prevent such an attack. Information such as the giaddr in
DHCPv4 or link address in the Relay-forward DHCPv6 message might be
used to detect and prevent this sort of attack.
One possible defense would be for the DHCP relay to insert a VSS
option or sub-option to override the DHCP client's VSS option.
Servers that implement the VSS option and sub-option MUST by default
disable use of the feature; it must specifically be enabled through
configuration. Moreover, a server SHOULD provide the ability to
selectively enable use of the feature under restricted conditions,
e.g., by enabling use of the option only from explicitly configured
client-ids, enabling its use only by clients on a particular subnet,
or restricting the VSSs from which addresses may be requested.
8. IANA Considerations
IANA is requested to assign DHCPv4 option number 221 for the DHCPv4
VSS option defined in Section 3.1, in accordance with [RFC 3942].
IANA is requested to assign sub-option number 151 for the DHCPv4
sub-option defined in Section 3.2 from the DHCP Relay Agent Sub-
options space [RFC 3046], in accordance with the spirit of [RFC
3942]. While [RFC 3942] doesn't explicitly mention the sub-option
space for the DHCP Relay Agent Information option [RFC 3046], sub-
option 151 is already in use by existing implementations of this
sub-option and the current draft is essentially compatible with these
current implementations.
IANA has assigned the value of TBD for the DHCPv6 VSS option defined
in Section 3.3.
While the type byte defined in Section 3.4 defines a number space
that could be managed by IANA, expansion of this number space is not
anticipated and so creation of a registry of these numbers is not
required by this document. In the event that additional values for
the type byte are defined in subsequent documents, IANA should at
that time create a registry for these type bytes. New values for the
type byte may only be defined by IETF Consensus, as described in
[RFC 2434]. Basically, this means that they are defined by RFCs
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approved by the IESG.
9. Acknowledgments
Bernie Volz recommended consolidation of the DHCPv4 option and sub-
option drafts after extensive review of the former drafts, and
provided valuable assistance in structuring and reviewing this
document. Alper Yegin expressed interest in the DHCPv6 VSS option,
resulting in this combined draft covering all three areas.
10. Normative References
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[RFC 2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997.
[RFC 2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
[RFC 2685] Fox, B., Gleeson, B., "Virtual Private Networks
Identifier", RFC 2685, September 1999.
[RFC 3046] Patrick, M., "DHCP Relay Agent Information Option", RFC
3046, January 2001.
[RFC 3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[RFC 3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633, December
2003.
11. Informative References
[RFC 951] Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951,
September 1985.
[RFC 1542] Wimer, W., "Clarifications and Extensions for the
Bootstrap Protol", RFC 1542, October 1993.
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
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[RFC 2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434, October
1998.
[RFC 3118] Droms, R. and W. Arbaugh, "Authentication for DHCP
Messages", RFC 3118, June 2001.
[RFC 3942] Volz, B., "Reclassifying Dynamic Host Configuration
Protocol version 4 (DHCPv4) Options", RFC 3942, November 2004.
[RFC 4030] Stapp, M. and T. Lemon, "The Authentication Suboption for
the Dynamic Host Configuration Protocol (DHCP) Relay Agent
Option", RFC 4030, March 2005.
[RFC 4388] Woundy, R. and K. Kinnear, "Dynamic Host Configuration
Protocol (DHCP) Leasequery", RFC 4388, February 2006.
[RFC 5007] Brzozowski, J., Kinnear, K., Volz, B., and S. Zeng,
"DHCPv6 Leasequery", RFC 5007, September 2007.
12. Authors' Addresses
Kim Kinnear
Cisco Systems
1414 Massachusetts Ave.
Boxborough, Massachusetts 01719
Phone: (978) 936-0000
EMail: kkinnear@cisco.com
Richard Johnson
Cisco Systems
170 W. Tasman Dr.
San Jose, CA 95134
Phone: (408) 526-4000
EMail: raj@cisco.com
Mark Stapp
Cisco Systems
1414 Massachusetts Ave.
Boxborough, Massachusetts 01719
Kinnear, et. al. Expires August 22, 2008 [Page 15]
Internet Draft Virtual Subnet Selection Options February 2008
Phone: (978) 936-0000
EMail: mjs@cisco.com
Jay Kumarasamy
Cisco Systems
170 W. Tasman Dr.
San Jose, CA 95134
Phone: (408) 526-4000
EMail: jayk@cisco.com
13. Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
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Copies of IPR disclosures made to the IETF Secretariat and any
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Kinnear, et. al. Expires August 22, 2008 [Page 16]
Internet Draft Virtual Subnet Selection Options February 2008
http://www.ietf.org/ipr.
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15. Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Kinnear, et. al. Expires August 22, 2008 [Page 17]
