draft-ietf-dhc-pv4-reconfigure-04.txt   draft-ietf-dhc-pv4-reconfigure-05.txt 
Submitted to DHC Working Group Yves T'Joens
Submitted to DHC Working Group Peter De Schrijver INTERNET DRAFT Christian Hublet
INTERNET DRAFT Yves T'Joens <draft-ietf-dhc-pv4-reconfigure-05.txt> Alcatel
<draft-ietf-dhc-pv4-reconfigure-04.txt> Christian Hublet Peter De Schrijver
Alcatel Mind
April 2001 June 2001
Expires September, 2001 Expires November, 2001
DHCP reconfigure extension DHCP reconfigure extension
Status of this memo Status of this memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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Abstract Abstract
This draft defines extensions to DHCP [DHCP] to allow dynamic This draft defines extensions to DHCP [DHCP] to allow dynamic
reconfiguration of a single host triggered by the DHCP server (eg. a reconfiguration of a single host triggered by the DHCP server (eg. a
new IP address). This is achieved by introducing a unicast FORCERENEW new IP address and/or local configuration parameters). This is
message which forces the client to the RENEW state. The behaviour for achieved by introducing a unicast FORCERENEW message which forces the
hosts using the DHCP INFORM message to obtain configuration client to the RENEW state. The behaviour for hosts using the DHCP
information is also described. INFORM message to obtain configuration information is also described.
1. Introduction 1. Introduction
The procedures as described within this draft allow the dynamic The procedures as described within this draft allow the dynamic
reconfiguration of individual hosts. reconfiguration of individual hosts.
1.1 Conventions 1.1 Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this
skipping to change at page 2, line 47 skipping to change at page 2, line 47
The procedures described above assume the server to send a unicast The procedures described above assume the server to send a unicast
FORCERENEW message to the client. Receipt of a multicast FORCERENEW FORCERENEW message to the client. Receipt of a multicast FORCERENEW
message by the client should be silently discarded. message by the client should be silently discarded.
It can be that a client has obtained a network address through some It can be that a client has obtained a network address through some
other means (e.g., manual configuration) and has used a DHCP INFORM other means (e.g., manual configuration) and has used a DHCP INFORM
request to obtain other local configuration parameters. Such clients request to obtain other local configuration parameters. Such clients
should respond to the receipt of a unicast FORCERENEW message with a should respond to the receipt of a unicast FORCERENEW message with a
new DHCP INFORM request so as to obtain a potential new set of local new DHCP INFORM request so as to obtain a potential new set of local
configuration parameters. configuration parameters. Note that the usage of these procedures are
limited to the set of options that are eligible for configuration by
DHCP and should not override manually configured parameters.
2.3 Rationale Note further that usage of the FORCERENEW message to reconfigure a
client address or local configuration parameters can lead to the
interruption of active sessions, and that as such these procedures
should be used in controlled circumstances.
This approach has a number of advantages. It does not require new 2.3 Example usage
states to be added to the DHCP client implementation. This minimizes
the amount of code to be changed. It also allows lease RENEWAL to be 2.3.1 Embedded DHCP clients
driven by the server, which can be used to optimize network usage or
DHCP server load. The autoconfiguration of home gateways (more generically Network
Termination equipment) for public networking purposes can be achieved
through means of DHCP, as described in [DSL_autoconf]. In order to
allow service changes or service interruption, the FORCERENEW message
can trigger the home gateway to contact the DHCP server, prior to the
expiry of the lease.
2.3.2 Hospitality service scenario
In self provisioned networks, e.g., hotel rooms, the hotel owned DHCP
server can hand out limited use IP addresses, that allows the
customer to consume local services or select external services from a
web browser interface. In order to allow external services through
other service providers, e.g., global internet services or enterprise
VPN services, the DHCP server can trigger the client to ask for a new
DHCP initialization session so as to obtain e.g., a globally routed
IP address.
2.3.3 Network renumbering
Under tightly controlled conditions, the FORCERENEW procedures can be
used to brute force the renumbering of entire subnets, client per
client, under control of a DHCP server.
2.4 Rationale
The approach as described in this document has a number of
advantages. It does not require new states to be added to the DHCP
client implementation. This minimizes the amount of code to be
changed. It also allows lease RENEWAL to be driven by the server,
which can be used to optimize network usage or DHCP server load.
3. Extended DHCP state diagram 3. Extended DHCP state diagram
+--------+ +------+ +--------+ +------+
| Init / | +-->+ Init +<---------------+-------------------+ | Init / | +-->+ Init +<---------------+-------------------+
| Reboot | | +--+---+ | | | Reboot | | +--+---+ | |
+---+----+ DHCPNAK/ -/Send DHCPDISCOVER | | +---+----+ DHCPNAK/ -/Send DHCPDISCOVER | |
| Restart | (broadcast) | | | Restart | (broadcast) | |
| | v v-------------+ | | | | v v-------------+ | |
-/Send DHCPREQUEST| +----+------+ DHCPOFFER/DHCPDECLINE | -/Send DHCPREQUEST| +----+------+ DHCPOFFER/DHCPDECLINE |
skipping to change at page 4, line 9 skipping to change at page 5, line 4
DHCPFORCERENEW message is TBD. DHCPFORCERENEW message is TBD.
6. Security Considerations 6. Security Considerations
As in some network environments FORCERENEW can be used to snoop and As in some network environments FORCERENEW can be used to snoop and
spoof traffic, the FORCERENEW message MUST be authenticated using the spoof traffic, the FORCERENEW message MUST be authenticated using the
procedures as described in [DHCP-AUTH]. FORCERENEW messages failing procedures as described in [DHCP-AUTH]. FORCERENEW messages failing
the authentication should be silently discarded by the client. the authentication should be silently discarded by the client.
7. References 7. References
[DHCP] R.Droms, "Dynamic Host Configuration Protocol", RFC 2131, [DHCP] R.Droms, "Dynamic Host Configuration Protocol", RFC 2131,
March 1997. March 1997.
[DHCP-AUTH] R. Droms et al., "Authentication for DHCP Messages", [DHCP-AUTH] R. Droms et al., "Authentication for DHCP Messages",
RFCxxxx, yyyy 2001. RFCxxxx, yyyy 2001.
[DSL_autoconf] Working Text WT-059, "Auto-configuration for Basic
Internet (IP-Based) Services", DSL Forum, May 2001
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
8. Acknowledgements 8. Acknowledgements
The authors would like to thank David Allan, Nortel, for the The authors would like to thank David Allan, Nortel, for the
constructive comments to these procedures. constructive comments to these procedures.
9. Contacts 9. Contacts
Peter De Schrijver
Alcatel Network Strategy Group
Francis Wellesplein 1, 2018 Antwerp, Belgium
Phone : +32 3 240 8569
E-mail : peter.de_schrijver@alcatel.be
Yves T'joens Yves T'joens
Alcatel Network Strategy Group Alcatel Network Strategy Group
Francis Wellesplein 1, 2018 Antwerp, Belgium Francis Wellesplein 1, 2018 Antwerp, Belgium
Phone : +32 3 240 7890 Phone : +32 3 240 7890
E-mail : yves.tjoens@alcatel.be E-mail : yves.tjoens@alcatel.be
Peter De Schrijver
Mind NV
Vaartkom 11
3000 Leuven
E-mail : p2@mind.be
Christian Hublet Christian Hublet
Alcatel Carrier Internetworking Division Alcatel Carrier Internetworking Division
De Villermontstraat 28, 2550 Kontich, Belgium De Villermontstraat 28, 2550 Kontich, Belgium
Phone : +32 3 450 3322 Phone : +32 3 450 3322
E-mail : Christian.Hublet@alcatel.be E-mail : Christian.Hublet@alcatel.be
8. Full Copyright Statement 8. Full Copyright Statement
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
 End of changes. 

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