PCP Working Group M. Boucadair
Internet-Draft France Telecom
Intended status: Standards Track R. Penno
Expires: February 7, 2013 D. Wing
Cisco
August 6, 2012
DHCP Options for the Port Control Protocol (PCP)
draft-ietf-pcp-dhcp-04
Abstract
This document specifies DHCP (IPv4 and IPv6) options to configure
hosts with Port Control Protocol (PCP) Server names. The use of
DHCPv4 or DHCPv6 depends on the PCP deployment scenario.
Requirements Language
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 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on February 7, 2013.
Copyright Notice
Copyright (c) 2012 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. DHCPv6 PCP Server Option . . . . . . . . . . . . . . . . . . . 4
4.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Client Behaviour . . . . . . . . . . . . . . . . . . . . . 5
5. DHCPv4 PCP Option . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2. Client Behaviour . . . . . . . . . . . . . . . . . . . . . 6
6. Use of PCP Server Names . . . . . . . . . . . . . . . . . . . 6
6.1. Name Resolution . . . . . . . . . . . . . . . . . . . . . 7
6.2. IP Address Selection . . . . . . . . . . . . . . . . . . . 7
6.2.1. Serial Queries . . . . . . . . . . . . . . . . . . . . 7
6.2.2. Examples . . . . . . . . . . . . . . . . . . . . . . . 8
6.2.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . 8
6.2.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . 8
6.2.2.3. Example 3 . . . . . . . . . . . . . . . . . . . . 9
7. Dual-Stack Hosts . . . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9.1. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . 10
9.2. DHCPv4 Option . . . . . . . . . . . . . . . . . . . . . . 10
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
11.1. Normative References . . . . . . . . . . . . . . . . . . . 10
11.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
This document defines DHCPv4 [RFC2131] and DHCPv6 [RFC3315] options
which can be used to provision PCP Server [I-D.ietf-pcp-base] names.
In order to make use of these options, this document assumes
appropriate name resolution means (e.g., Section 6.1.1 of [RFC1123])
are available on the host client.
The use of DHCPv4 or DHCPv6 depends on the PCP deployment scenarios.
2. Terminology
This document makes use of the following terms:
o PCP Server denotes a functional element which receives and
processes PCP requests from a PCP Client. A PCP Server can be co-
located with or be separated from the function (e.g., NAT,
Firewall) it controls. Refer to [I-D.ietf-pcp-base].
o PCP Client denotes a PCP software instance responsible for issuing
PCP requests to a PCP Server. Refer to [I-D.ietf-pcp-base].
o DHCPv4 refers to the Dynamic Host Configuration Protocol [RFC2131]
for IPv4.
o DHCP refers to both DHCPv4 [RFC2131] and DHCPv6 [RFC3315].
o DHCP client (or client) denotes a node that initiates requests to
obtain configuration parameters from one or more DHCP servers.
o DHCP server (or server) refers to a node that responds to requests
from DHCP clients.
o Name is a domain name that contains one or more labels. In
particular, a PCP name may be structured as DNS qualified name or
be composed of strings such as can be passed to getaddrinfo
(Section 6.1 of [RFC3493]), including address literals, etc.
3. Rationale
Both IP Address and Name DHCP options have been considered in early
stages of this specification. This flexibility aims to let service
providers to make their own engineering choices and use the
convenient option according to their deployment context.
Nevertheless, DHC WG's position is this flexibility has some
drawbacks such as inducing errors (See Section 7 of
[I-D.ietf-dhc-option-guidelines]). Therefore, only the Name option
is maintained within this document.
This document defines an option to carry a name rather than an IP
address. This choice is motivated by operational considerations: In
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particular, some Service Providers are considering two levels of
redirection:
(1) The first level is national-wise and undertaken by DHCP: a
regional-specific Name will be returned;
(2) The second level is done during the resolution of the regional-
specific Name to redirect the customer to a regional PCP server
among a pool deployed regionally.
Distinct operational teams are responsible for each of the above
mentioned levels. A clear separation between the functional
perimeter of each team is a sensitive task for the maintenance of the
offered services. Regional teams will require to introduce new
resources (e.g., new PCP-controlled devices such as Carrier Grade
NATs (CGNs, [I-D.ietf-behave-lsn-requirements])) to meet an increase
of customer base. Operations related to the introduction of these
new devices (e.g., addressing, redirection, etc.) are implemented
locally. Having this regional separation provides flexibility to
manage portions of network operated by dedicated teams. This two-
level redirection can not be met by the IP Address option.
In addition to the operational considerations:
o The use of the Name for NAT64 [RFC6146] might be suitable for
load-balancing purposes;
o For the DS-Lite case [RFC6333], if the encapsulation mode is used
to send PCP messages, an IP address may be used since the AFTR
selection is already done via the AFTR_NAME DHCPv6 option
[