draft-ietf-dhc-fqdn-opt-00.txt   draft-ietf-dhc-fqdn-opt-01.txt 
Network Working Group Yakov Rekhter, Cisco Systems Network Working Group Yakov Rekhter, Cisco Systems
Internet Draft Ralph Droms, Bucknell University INTERNET DRAFT Ralph Droms, Bucknell University
Expiration Date: August 1996 February 1996 Obsoletes: draft-ietf-dhc-fqdn-opt-00.txt April 1996
Expires October 1996
FQDN DHCP Option An option for FQDNs in DHCP options
draft-ietf-dhc-fqdn-opt-00.txt <draft-ietf-dhc-fqdn-opt-01.txt>
1. Status of this Memo Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. 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.''
To learn the current status of any Internet-Draft, please check the To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
ftp.isi.edu (US West Coast). ftp.isi.edu (US West Coast).
2. Abstract Abstract
DHCP [DHCP] can be used to automate the process of configuring TCP/IP DHCP [DHCP] can be used to automate the process of configuring TCP/IP
host computers. However, some of the DHCP options carry IP addresses host computers. However, some of the DHCP options carry IP addresses
rather than Fully Qualified Domain Names (FQDN). Use of IP addresses rather than Fully Qualified Domain Names (FQDN). Use of IP addresses
constrains the DHCP client to use the addresses that were in use at constrains the DHCP client to use the addresses that were in use at
the time the client received its configuration information; these the time the client received its configuration information; these
addresses may change over time, (e.g., a server may be assigned a new addresses may change over time, (e.g., a server may be assigned a new
IP address), so that the IP addresses used by the client may become IP address), so that the IP addresses used by the client may become
invalid. invalid.
An alternative to passing IP addresses is to pass FQDNs instead of An alternative to passing IP addresses is to pass FQDNs instead of
(numeric) IP addresses. Doing this allows to defer binding between a (numeric) IP addresses. Doing this allows to defer binding between a
particular network entity (e.g., a server) and its IP address until particular network entity (e.g., a server) and its IP address until
run time. As stated in [Carpenter:95], "Deferring the binding avoids run time. As stated in [Carpenter:95], "Deferring the binding avoids
the risk of changed mapping between IP addresses and specific network the risk of changed mapping between IP addresses and specific network
entities (due to changing addressing information). Moreover, entities (due to changing addressing information). Moreover,
reliance on FQDNs (rather than IP addresses) also localizes to the reliance on FQDNs (rather than IP addresses) also localizes to the
DNS the changes needed to deal with changing addressing information DNS the changes needed to deal with changing addressing information
due to renumbering." due to renumbering."
DRAFT An option for FQDNs in DHCP options April 1996
This document defines a new DHCP option that allows the use of FQDNs This document defines a new DHCP option that allows the use of FQDNs
instead of IP addresses in DHCP options. instead of IP addresses in DHCP options.
3. Definitions Definitions
The following defines the format of the FQDN option. The following defines the format of the FQDN option.
+----------+----------+ +----------+----------+
| Code | Length | | Code | Length |
+----------+----------+---------+-----------+-------------------- +----------+----------+---------+-----------+--------------------
|Subcode |Sublength | FQDN |Subcode |Sublength | FQDN
+----------+----------+---------+-----------+-------------------- +----------+----------+---------+-----------+--------------------
.................. ..................
skipping to change at page 3, line 6 skipping to change at page 3, line 5
FQDN carried in the option. The FQDN field carries the FQDN itself. FQDN carried in the option. The FQDN field carries the FQDN itself.
More that one triple with a given subcode may appear within a single More that one triple with a given subcode may appear within a single
FQDN option. Options that can carry a list of IP addresses should be FQDN option. Options that can carry a list of IP addresses should be
coded as multiple subcodes in the FQDN option, to differentiate among coded as multiple subcodes in the FQDN option, to differentiate among
the variable-length FQDNs. the variable-length FQDNs.
This option only allows the use of FQDNs for options that have been This option only allows the use of FQDNs for options that have been
elsewhere defined to carry IP addresses. elsewhere defined to carry IP addresses.
4. Example DRAFT An option for FQDNs in DHCP options April 1996
Example
The following illustrates how the FQDN option could be used to carry The following illustrates how the FQDN option could be used to carry
FQDNs for 2 LPR Servers with FQDNs lpr1.xxx.org and lpr2.yy.org, and FQDNs for 2 LPR Servers with FQDNs lpr1.xxx.org and lpr2.yy.org, and
one Network Information Server with FQDN nis.zzzz.org. one Network Information Server with FQDN nis.zzzz.org.
+---+---+ +---+---+
|xx |41 | |xx |41 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|41 |12 | n | i | s | . | z | z | z | z | . | o | r | g | |41 |12 | n | i | s | . | z | z | z | z | . | o | r | g |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| 9 |12 | l | p | r | 1 | . | x | x | x | . | o | r | g | | 9 |12 | l | p | r | 1 | . | x | x | x | . | o | r | g |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| 9 |11 | l | p | r | 2 | . | y | y | . | o | r | g | | 9 |11 | l | p | r | 2 | . | y | y | . | o | r | g |
+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+
5. Security Considerations Security Considerations
Security issues are not discussed in this document. Security issues are not discussed in this document.
6. References References
[Carpenter:95] Carpenter, B., Rekhter, Y., "Renumbering considered [Carpenter:95] Carpenter, B., Rekhter, Y., "Renumbering considered
unavoidable", Internet Draft unavoidable", Internet Draft
[DHCP] Droms, R., "Dynamic Host Configuration Protocol", RFC1541, [DHCP] Droms, R., "Dynamic Host Configuration Protocol", RFC1541,
October 1993 October 1993
7. Acknowledgements Acknowledgements
To be supplied. To be supplied.
8. Author Information DRAFT An option for FQDNs in DHCP options April 1996
Author Information
Yakov Rekhter Yakov Rekhter
cisco Systems, Inc. cisco Systems, Inc.
170 Tasman Dr. 170 Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
Phone: (914) 528-0090 Phone: (914) 528-0090
email: yakov@cisco.com email: yakov@cisco.com
Ralph Droms Ralph Droms
Computer Science Department Computer Science Department
 End of changes. 

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