ALTO S. Kiesel
Internet-Draft K. Krause
Intended status: Experimental University of Stuttgart
Expires: November 17, 2013 M. Stiemerling
NEC Europe Ltd.
May 16, 2013
Third-Party ALTO Server Discovery (3pdisc)
draft-kist-alto-3pdisc-03
Abstract
The goal of Application-Layer Traffic Optimization (ALTO) is to
provide guidance to applications that have to select one or several
hosts from a set of candidates capable of providing a desired
resource. ALTO is realized by a client-server protocol. Before an
ALTO client can ask for guidance it needs to discover one or more
ALTO servers that can provide suitable guidance.
This document specifies a procedure for third-party ALTO server
discovery, which can be used if the ALTO client is not co-located
with the actual resource consumer, but instead embedded in a third
party such as a peer-to-peer tracker.
Technically, the algorithm specified in this document takes one
IP address and a U-NAPTR Service Parameter (i.e., "ALTO:http" or
"ALTO:https") as parameters. It performs several DNS lookups (for
PTR, SOA, and U-NAPTR resource records) and returns one or more
URI(s) of information resources related to that IP address.
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Terminology and Requirements Language
This document makes use of the ALTO terminology defined in RFC 5693
[RFC5693].
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
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 November 17, 2013.
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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Third-party ALTO Server Discovery Procedure Specification . . 5
2.1. Interface . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Basic Principle . . . . . . . . . . . . . . . . . . . . . 5
2.3. Overall Procedure . . . . . . . . . . . . . . . . . . . . 6
2.4. Specification of Tasks and Conditional Branches . . . . . 7
2.4.1. T1/B1: PTR Lookup on IP Address . . . . . . . . . . . 7
2.4.2. T2/B2: U-NAPTR Lookup on yielded PTR value(s) . . . . 7
2.4.3. B3/T3/B4: Acquire SOA Record for Reverse Zone . . . . 8
2.4.4. T4/B5: U-NAPTR Lookup on SOA-MNAME . . . . . . . . . . 9
2.4.5. T5: Sort the Results by Order and Preference . . . . . 9
3. Implementation, Deployment, and Operational Considerations . . 10
3.1. Considerations for ALTO Clients . . . . . . . . . . . . . 10
3.1.1. Resource Consumer Initiated Discovery . . . . . . . . 10
3.1.2. IPv4/v6 Dual Stack, Multihoming, NAT, and Host
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