--- 1/draft-ietf-6man-addr-select-opt-11.txt 2013-09-20 21:14:24.528731461 -0700 +++ 2/draft-ietf-6man-addr-select-opt-12.txt 2013-09-20 21:14:24.552732054 -0700 @@ -1,20 +1,20 @@ 6man Working Group A. Matsumoto Internet-Draft T. Fujisaki Intended status: Standards Track NTT -Expires: February 08, 2014 T. Chown +Expires: March 25, 2014 T. Chown University of Southampton - August 07, 2013 + September 21, 2013 Distributing Address Selection Policy using DHCPv6 - draft-ietf-6man-addr-select-opt-11.txt + draft-ietf-6man-addr-select-opt-12.txt Abstract RFC 6724 defines default address selection mechanisms for IPv6 that allow nodes to select an appropriate address when faced with multiple source and/or destination addresses to choose between. RFC 6724 allows for the future definition of methods to administratively configure the address selection policy information. This document defines a new DHCPv6 option for such configuration, allowing a site administrator to distribute address selection policy overriding the @@ -29,21 +29,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on February 08, 2014. + This Internet-Draft will expire on March 25, 2014. Copyright Notice Copyright (c) 2013 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 publication of this document. Please review these documents @@ -62,40 +62,43 @@ the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 1. Introduction [RFC6724] describes default algorithms for selecting an address when a node has multiple destination and/or source addresses to choose - from by using an address selection policy. In Section 2 of RFC 6724, - it is suggested that the default policy table may be administratively - configured to suit the specific needs of a site. This specification - defines a new DHCPv6 option for such configuration. + from by using an address selection policy. This specification + defines a new DHCPv6 option for configuring the default policy table. Some problems were identified with the default address selection policy as originally defined in [RFC3484]. As a result, RFC 3484 was updated and obsoleted by [RFC6724]. While this update corrected a number of issues identifed from operational experience, it is unlikely that any default policy will suit all scenarios, and thus mechanisms to control the source address selection policy will be necessary. Requirements for those mechanisms are described in [RFC5221], while solutions are discussed in [I-D.ietf-6man-addr-select-considerations]. Those documents have helped shape the improvements in the default address selection algorithm in [RFC6724] as well as the requirements for the DHCPv6 option defined in this specification. -1.1. Conventions Used in This Document + This option's concept is to serve as a hint for a node about how to + behave in the network. Ultimately, while the node's administrator + can control how to deal with the received policy information, the + implementation SHOULD follow the method described below uniformly, to + ease troubleshooting and to reduce operational costs. +1.1. Conventions Used in This Document 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 [RFC2119]. 1.2. Terminology This document uses the terminology defined in [RFC2460] and the DHCPv6 specification defined in [RFC3315] 2. Address Selection options @@ -134,28 +137,32 @@ A: Automatic Row Addition flag. This flag toggles the Automatic Row Addition flag at client hosts, which is described in section 2.1 of [RFC6724]. If this flag is set to 1, it does not change client host behavior, that is, a client MAY automatically add additional site-specific rows to the policy table. If set to 0, the Automatic Row Addition flag is disabled, and a client SHOULD NOT automatically add rows to the policy table. If the option contains a POLICY TABLE option, this flag is meaningless, and automatic row addition SHOULD NOT be performed against the - distributed policy table. + distributed policy table. This flag SHOULD be set to 0 only + when the Automatic Row Addition at client hosts is harmful for + site-specific reasons. P: Privacy Preference flag. This flag toggles the Privacy Preference flag on client hosts, which is described in section 5 of [RFC6724]. If this flag is set to 1, it does not change client host behavior, that is, a client will prefer temporary addresses [RFC4941]. If set to 0, the Privacy Preference flag - is disabled, and a client will prefer public addresses. + is disabled, and a client will prefer public addresses. This + flag SHOULD be set to 0 only when the temporary addresses should + not be preferred for site-specific reasons. POLICY TABLE OPTIONS: Zero or more Address Selection Policy Table options, as described below. This option corresponds to a row in the policy table defined in section 2.1 of [RFC6724]. 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_ADDRSEL_TABLE | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -176,21 +183,23 @@ label: An 8-bit unsigned integer; this value is for correlation of source address prefixes and destination address prefixes. This field is used to deliver a label value in the [RFC6724] policy table. precedence: An 8-bit unsigned integer; this value is used for sorting destination addresses. This field is used to to deliver a precedence value in [RFC6724] policy table. prefix-len: An 8-bit unsigned integer; the number of leading bits in - the prefix that are valid. The value ranges from 0 to 128. + the prefix that are valid. The value ranges from 0 to 128. If + an option with a prefix length greater than 128 is included, the + whole Address Selection option MUST be ignored. prefix: A variable-length field containing an IP address or the prefix of an IP address. An IPv4-mapped address [RFC4291] must be used to represent an IPv4 address as a prefix value. This field is padded with zeros up to the nearest octet boundary when prefix-len is not divisible by 8. This can be expressed using the following equation: (prefix-len + 7)/8 So the length of this field should be between 0 and 16 bytes. For example, the prefix 2001:db8::/60 would be encoded with an prefix-len of 60, the prefix would be 8 octets and would contains octets 20 01 0d b8 @@ -218,24 +227,24 @@ (a) replace the existing flags and active policy table with the DHCPv6 distributed flags and policy table. (b) preserve the existing flags and active policy table, whether this be the default policy table, or user configured policy. Choice (a) SHOULD be the default, i.e. that the policy table is not explictly configured by the user. -3.2. Handling stale policy tables +3.2. Handling stale distributed flags and policy table - When the information from the DHCP server goes stale, the policy - received from the DHCP server SHOULD be deprecated. + When the information from the DHCP server goes stale, the flags and + the policy table received from the DHCP server SHOULD be deprecated. The received information can be considered stale in several cases, e.g., when the interface goes down, the DHCP server does not respond for a certain amount of time, and the Information Refresh Time is expired. 3.3. Handling multiple interfaces The policy table, and other parameters specified in this document, are node-global information by their nature. One reason being that