draft-ietf-dhc-subnet-option-05.txt | draft-ietf-dhc-subnet-option-06.txt | |||
---|---|---|---|---|
Network Working Group G. Waters | Network Working Group G. Waters | |||
INTERNET-DRAFT Nortel Networks | INTERNET-DRAFT Nortel Networks | |||
June 2000 | July 2000 | |||
The Subnet Selection Option for DHCP | The IPv4 Subnet Selection Option for DHCP | |||
<draft-ietf-dhc-subnet-option-05.txt> | <draft-ietf-dhc-subnet-option-06.txt> | |||
Wednesday, June 07, 2000, 4:44 PM | Friday, July 14, 2000, 2:07 PM | |||
Status of this Memo | Status of this Memo | |||
This document is an Internet-Draft and is in full conformance with all | This document is an Internet-Draft and is in full conformance with all | |||
provisions of Section 10 of RFC2026. | provisions of Section 10 of RFC2026. | |||
Internet-Drafts are working documents of the Internet Engineering Task | Internet-Drafts are working documents of the Internet Engineering Task | |||
Force (IETF), its areas, and its working groups. Note that other | Force (IETF), its areas, and its working groups. Note that other | |||
groups may also distribute working documents as Internet-Drafts. | groups may also distribute working documents as Internet-Drafts. | |||
Internet-Drafts are draft documents valid for a maximum of six months | Internet-Drafts are draft documents valid for a maximum of six months | |||
and may be updated, replaced, or obsoleted by other documents at any | and may be updated, replaced, or obsoleted by other documents at any | |||
time. It is inappropriate to use Internet-Drafts as reference | time. It is inappropriate to use Internet-Drafts as reference | |||
material or to cite them other than as "work in progress." | material or to cite them other than as "work in progress." | |||
The list of current Internet-Drafts can be accessed at | The list of current Internet-Drafts can be accessed at | |||
http://www.ietf.org/ietf/1id-abstracts.txt | http://www.ietf.org/ietf/1id-abstracts.txt | |||
The list of Internet-Draft Shadow Directories can be accessed at | The list of Internet-Draft Shadow Directories can be accessed at | |||
http://www.ietf.org/shadow.html. | http://www.ietf.org/shadow.html. | |||
To learn the current status of any Internet-Draft, please check the | ||||
"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow | ||||
Directories on ds.internic.net (US East Coast), nic.nordu.net | ||||
(Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). | ||||
Copyright Notice | Copyright Notice | |||
Copyright (C) The Internet Society (2000). All Rights Reserved. | Copyright (C) The Internet Society (2000). All Rights Reserved. | |||
Abstract | Abstract | |||
This memo defines a new DHCP option for selecting the subnet on which | This memo defines a new DHCP option for selecting the subnet on which | |||
to allocate an address. This option would override a DHCP server's | to allocate an address. This option would override a DHCP server's | |||
normal methods of selecting the subnet on which to allocate an address | normal methods of selecting the subnet on which to allocate an address | |||
for a client. | for a client. | |||
Waters Expires: Jun 2000 + 6 months [Page 1] | Waters Expires: Jul 2000 + 6 months [Page 1] | |||
Table of Contents | Table of Contents | |||
1. Introduction......................................................2 | 1. Introduction......................................................2 | |||
1.1. Motivational Example.........................................2 | 1.1. Motivational Example.........................................2 | |||
2. Subnet Selection Option Definition................................3 | 2. Subnet Selection Option Definition................................3 | |||
3. Intellectual Property.............................................4 | 3. Intellectual Property.............................................4 | |||
4. IANA Considerations...............................................4 | 4. IANA Considerations...............................................5 | |||
5. Acknowledgements..................................................5 | 5. Acknowledgements..................................................5 | |||
6. Security Considerations...........................................5 | 6. Security Considerations...........................................5 | |||
7. References........................................................5 | 7. References........................................................5 | |||
8. Editor's Addresses................................................5 | 8. Editor's Addresses................................................5 | |||
9. Full Copyright Statement..........................................5 | 9. Full Copyright Statement..........................................6 | |||
1. Introduction | 1. Introduction | |||
The Dynamic Host Configuration Protocol (DHCP) [RFC2131] provides a | ||||
framework for passing configuration information to hosts on a TCP/IP | ||||
network. RFC 2132 [RFC2132] specifies DHCP option configuration | ||||
information that may be carried in DHCP packets to/from the DHCP | ||||
server and the DHCP client. This document specifies a new DHCP option. | ||||
To select the subnet on which to allocate an address, the DHCP server | To select the subnet on which to allocate an address, the DHCP server | |||
determines the subnet from which the request originated, and then | determines the subnet from which the request originated, and then | |||
selects an address on the originating subnet or on a subnet that is on | selects an address on the originating subnet or on a subnet that is on | |||
the same network segment as the originating subnet. The subnet from | the same network segment as the originating subnet. The subnet from | |||
which the request originates can be determined by: | which the request originates can be determined by: | |||
o Using the subnet address of the giaddr field in the DHCP packet | o Using the subnet address of the giaddr field in the DHCP packet | |||
header, or if the giaddr field is zero; | header, or if the giaddr field is zero; | |||
o Using the subnet address of the local interface on which the DHCP | o Using the subnet address of the local interface on which the DHCP | |||
skipping to change at line 92 | skipping to change at line 92 | |||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this | "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this | |||
document are to be interpreted as described in [RFC2119]. | document are to be interpreted as described in [RFC2119]. | |||
1.1. Motivational Example | 1.1. Motivational Example | |||
An example of where this option could be useful is in a device (e.g.: | An example of where this option could be useful is in a device (e.g.: | |||
a RAS device) that is allocating addresses on behalf of its clients. | a RAS device) that is allocating addresses on behalf of its clients. | |||
In this case the device would be allocating addresses through DHCP and | In this case the device would be allocating addresses through DHCP and | |||
then managing those addresses among its clients. | then managing those addresses among its clients. | |||
Waters Expires: Jul 2000 + 6 months [Page 2] | ||||
In this scenario, the device is connected to a private "internal" | In this scenario, the device is connected to a private "internal" | |||
network on which the DHCP server would be located. The device is also | network on which the DHCP server would be located. The device is also | |||
connected to one or more service providing "external" networks (i.e.: | connected to one or more service providing "external" networks (i.e.: | |||
the networks that the device's clients are connected to). Furthermore, | the networks that the device's clients are connected to). Furthermore, | |||
the internal network is not IP connected to the external networks, | the internal network is not IP connected to the external networks, | |||
Waters Expires: Jun 2000 + 6 months [Page 2] | ||||
although inside the device there is connectivity between the internal | although inside the device there is connectivity between the internal | |||
and external networks (e.g.: though the backplane). | and external networks (e.g.: though the backplane). | |||
Recall that the device is allocating addresses for its clients on the | Recall that the device is allocating addresses for its clients on the | |||
external networks and that there is no IP connectivity between the | external networks and that there is no IP connectivity between the | |||
internal network and the external networks. The DHCP requests cannot | internal network and the external networks. The DHCP requests cannot | |||
originate from the external networks since packets cannot be routed | originate from the external networks since packets cannot be routed | |||
between the external network and the internal network. Thus, the DHCP | between the external network and the internal network. Thus, the DHCP | |||
requests must originate from the internal network. The problem with | requests must originate from the internal network. The problem with | |||
originating the DHCP requests from the internal network is that the | originating the DHCP requests from the internal network is that the | |||
skipping to change at line 123 | skipping to change at line 122 | |||
The device would send its DHCP request on the internal subnet, but | The device would send its DHCP request on the internal subnet, but | |||
would include the subnet selection option containing the address of | would include the subnet selection option containing the address of | |||
the external subnet on which it requires the address. The subnet | the external subnet on which it requires the address. The subnet | |||
selection option instructs the DHCP server to allocate the address on | selection option instructs the DHCP server to allocate the address on | |||
the requested subnet as opposed to the normal operation of allocating | the requested subnet as opposed to the normal operation of allocating | |||
the address on the subnet from which the DHCP request originated. | the address on the subnet from which the DHCP request originated. | |||
2. Subnet Selection Option Definition | 2. Subnet Selection Option Definition | |||
The subnet selection option is a DHCP option. The option contains a | The subnet selection option is a DHCP option. The option contains a | |||
single IP address that is the address of a subnet. The value for the | single IPv4 address that is the address of a subnet. The value for the | |||
subnet address is determined by taking any IP address on the subnet | subnet address is determined by taking any IPv4 address on the subnet | |||
and ANDing that address with the subnet mask (i.e.: the network and | and ANDing that address with the subnet mask (i.e.: the network and | |||
subnet bits are left alone and the remaining (address) bits are set to | subnet bits are left alone and the remaining (address) bits are set to | |||
zero). When the DHCP server is allocating an address and this option | zero). When the DHCP server is configured to respond to this option, | |||
is present then the DHCP server MUST allocate the address on either: | is allocating an address, and this option is present then the DHCP | |||
server MUST allocate the address on either: | ||||
o the subnet specified in the subnet selection option, or; | o the subnet specified in the subnet selection option, or; | |||
o a subnet on the same network segment as the subnet specified in the | o a subnet on the same network segment as the subnet specified in the | |||
subnet selection option. | subnet selection option. | |||
The format of the option is: | The format of the option is: | |||
Code Len IP Address | Code Len IPv4 Address | |||
+-----+-----+-----+-----+-----+-----+ | +-----+-----+-----+-----+-----+-----+ | |||
| TBD | 4 | A1 | A2 | A3 | A4 | | | TBD | 4 | A1 | A2 | A3 | A4 | | |||
+-----+-----+-----+-----+-----+-----+ | +-----+-----+-----+-----+-----+-----+ | |||
Servers supporting this option MUST return an identical copy of the | Waters Expires: Jul 2000 + 6 months [Page 3] | |||
option to any client that sends it, regardless of whether or not the | Servers configured to support this option MUST return an identical | |||
client requests the option in a parameter request list. Clients using | copy of the option to any client that sends it, regardless of whether | |||
this option MUST discard DHCPOFFER or DHCPACK packets that do not | or not the client requests the option in a parameter request list. | |||
contain this option. | Clients using this option MUST discard DHCPOFFER or DHCPACK packets | |||
that do not contain this option. | ||||
Waters Expires: Jun 2000 + 6 months [Page 3] | ||||
This option does not require changes to operations or features of the | This option does not require changes to operations or features of the | |||
DHCP server other than to select the subnet on which to allocate an | DHCP server other than to select the subnet on which to allocate an | |||
address. For example, the handling of DHCPDISCOVER for an unknown | address. For example, the handling of DHCPDISCOVER for an unknown | |||
subnet should continue to operate unchanged. | subnet should continue to operate unchanged. | |||
When this option is present and the server supports this option, the | When this option is present and the server is configured to support | |||
server MUST NOT offer an address that is not on the requested subnet | this option, the server MUST NOT offer an address that is not on the | |||
or network segment. | requested subnet or network segment. Servers that do not understand | |||
this option will allocate an address using their normal algorithms and | ||||
will not return this option in the DHCPOFFER or DHCPACK. In this case | ||||
the client will discard the DHCPOFFER or DHCPACK. Servers that | ||||
understand this option but are administratively configured to ignore | ||||
the option MUST ignore the option, use their normal algorithms to | ||||
allocate an address, and MUST NOT return this option in the DHCPOFFER | ||||
or DHCPACK. In this case the client will discard the DHCPOFFER or | ||||
DHCPACK. | ||||
During an address renew, the DHCP server may send a DHCPACK directly | During an address renew, the DHCP server may send a DHCPACK directly | |||
to the allocated address, however packets from the DHCP server may not | to the allocated address, however packets from the DHCP server may not | |||
be routable to the address. Thus, in all packets that the DHCP client | be routable to the address. Thus, in all packets that the DHCP client | |||
sends that contain the subnet selection option, the giaddr field in | sends that contain the subnet selection option, the giaddr field in | |||
the BOOTP header MUST be set to an IP address on which the DHCP client | the BOOTP header MUST be set to an IPv4 address on which the DHCP | |||
will accept DHCP packets (e.g.: the address of the subnet connected to | client will accept DHCP packets (e.g.: the address on the subnet | |||
the internal network). | connected to the internal network). | |||
The IP address to which a DHCP server sends a reply to MUST be the | The IPv4 address to which a DHCP server sends a reply to MUST be the | |||
same as it would chose when this option is not present. | same as it would chose when this option is not present. | |||
3. Intellectual Property | 3. Intellectual Property | |||
The IETF takes no position regarding the validity or scope of any | The IETF takes no position regarding the validity or scope of any | |||
intellectual property or other rights that might be claimed to pertain | intellectual property or other rights that might be claimed to pertain | |||
to the implementation or use of the technology described in this | to the implementation or use of the technology described in this | |||
document or the extent to which any license under such rights might or | document or the extent to which any license under such rights might or | |||
might not be available; neither does it represent that it has made any | might not be available; neither does it represent that it has made any | |||
effort to identify any such rights. Information on the IETF's | effort to identify any such rights. Information on the IETF's | |||
procedures with respect to rights in standards-track and standards- | procedures with respect to rights in standards-track and standards- | |||
related documentation can be found in BCP-11. | related documentation can be found in BCP-11. | |||
Copies of claims of rights made available for publication and any | Copies of claims of rights made available for publication and any | |||
assurances of licenses to be made available, or the result of an | assurances of licenses to be made available, or the result of an | |||
attempt made to obtain a general license or permission for the use of | attempt made to obtain a general license or permission for the use of | |||
such proprietary rights by implementers or users of this specification | such proprietary rights by implementers or users of this specification | |||
can be obtained from the IETF Secretariat. | can be obtained from the IETF Secretariat. | |||
Waters Expires: Jul 2000 + 6 months [Page 4] | ||||
The IETF invites any interested party to bring to its attention any | The IETF invites any interested party to bring to its attention any | |||
copyrights, patents or patent applications, or other proprietary | copyrights, patents or patent applications, or other proprietary | |||
rights which may cover technology that may be required to practice | rights which may cover technology that may be required to practice | |||
this standard. Please address the information to the IETF Executive | this standard. Please address the information to the IETF Executive | |||
Director. | Director. | |||
4. IANA Considerations | 4. IANA Considerations | |||
IANA has assigned a value of TBD for the DHCP option code described in | IANA has assigned a value of TBD for the DHCP option code described in | |||
this document. | this document. | |||
Waters Expires: Jun 2000 + 6 months [Page 4] | ||||
5. Acknowledgements | 5. Acknowledgements | |||
This document is the result of work undertaken the by DHCP working | This document is the result of work undertaken the by DHCP working | |||
group. Thanks to Ted Lemon, Tim Aston and Ralph Droms for their | group. Thanks to Ted Lemon, Tim Aston and Ralph Droms for their | |||
helpful comments in this work. | helpful comments in this work. | |||
6. Security Considerations | 6. Security Considerations | |||
DHCP currently provides no authentication or security mechanisms. | DHCP currently provides no authentication or security mechanisms. | |||
Potential exposures to attack are discussed is section 7 of the | Potential exposures to attack are discussed is section 7 of the | |||
skipping to change at line 233 | skipping to change at line 241 | |||
March 1997. | March 1997. | |||
[RFC2132] Alexander, S. and Droms, R., "DHCP Options and BOOTP Vendor | [RFC2132] Alexander, S. and Droms, R., "DHCP Options and BOOTP Vendor | |||
Extensions", RFC 2132, March 1997. | Extensions", RFC 2132, March 1997. | |||
8. Editor's Addresses | 8. Editor's Addresses | |||
Glenn Waters | Glenn Waters | |||
Nortel Networks | Nortel Networks | |||
310-875 Carling Avenue, | 310-875 Carling Avenue, | |||
Waters Expires: Jul 2000 + 6 months [Page 5] | ||||
Ottawa, Ontario K1S 5P1 | Ottawa, Ontario K1S 5P1 | |||
Canada | Canada | |||
Phone: +1 613-798-4925 | Phone: +1 613-798-4925 | |||
Email: gww@nortelnetworks.com | Email: gww@nortelnetworks.com | |||
9. Full Copyright Statement | 9. Full Copyright Statement | |||
Copyright (C) The Internet Society (2000). All Rights Reserved. | Copyright (C) The Internet Society (2000). All Rights Reserved. | |||
This document and translations of it may be copied and furnished to | This document and translations of it may be copied and furnished to | |||
others, and derivative works that comment on or otherwise explain it | others, and derivative works that comment on or otherwise explain it | |||
or assist in its implementation may be prepared, copied, published and | or assist in its implementation may be prepared, copied, published and | |||
Waters Expires: Jun 2000 + 6 months [Page 5] | ||||
distributed, in whole or in part, without restriction of any kind, | distributed, in whole or in part, without restriction of any kind, | |||
provided that the above copyright notice and this paragraph are | provided that the above copyright notice and this paragraph are | |||
included on all such copies and derivative works. However, this | included on all such copies and derivative works. However, this | |||
document itself may not be modified in any way, such as by removing | document itself may not be modified in any way, such as by removing | |||
the copyright notice or references to the Internet Society or other | the copyright notice or references to the Internet Society or other | |||
Internet organizations, except as needed for the purpose of developing | Internet organizations, except as needed for the purpose of developing | |||
Internet standards in which case the procedures for copyrights defined | Internet standards in which case the procedures for copyrights defined | |||
in the Internet Standards process must be followed, or as required to | in the Internet Standards process must be followed, or as required to | |||
translate it into languages other than English. | translate it into languages other than English. | |||
The limited permissions granted above are perpetual and will not be | The limited permissions granted above are perpetual and will not be | |||
revoked by the Internet Society or its successors or assigns. | revoked by the Internet Society or its successors or assigns. | |||
This document and the information contained herein is provided on an | This document and the information contained herein is provided on an | |||
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING | "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING | |||
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT | TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT | |||
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN | NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN | |||
WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF | WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF | |||
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. | MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. | |||
Waters Expires: Jun 2000 + 6 months [Page 6] | Waters Expires: Jul 2000 + 6 months [Page 6] | |||
End of changes. | ||||
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