The LoST-Validation S-NAPTR Application Service Tag
draft-gellens-lost-validation-03

Abstract

This document adds LoST-Validation to the S-NAPTR Application Service Tag IANA registry.

Status of This Memo

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Table of Contents

• 1. Document Scope
• 2. Introduction
• 3. The LoST-Validation Application Service Tag
• 4. Security Considerations
• 5. IANA Considerations
• 5.1. S-NAPTR Registration
• 6. Acknowledgements
• 7. Changes from Previous Versions
• 7.1. Changes from -00 to -01
• 7.2. Changes from -01 to -02
• 7.3. Changes from -02 to -03
• 8. References
• 8.1. Normative References
• 8.2. Informative references
• Authors' Addresses

1. Document Scope

This document only adds a new Service Tag.

2. Introduction

The Location-to-Service Translation Protocol, LoST [RFC5222] defines a mapping service with the additional ability to request that a civic address be validated. The National Emergency Number Association (NENA) has defined an architecture (known as "i3" [NENA-i3]) which defines the mapping and routing functions as two distinct roles, defined as an Emergency Call Routing Function (ECRF) and a Location Verification Function (LVF). NENA i3 requires that the mapping (ECRF) and validation (LVF) functions be separable, so that an entity responsible for a LoST server cluster can decide to provide mapping and validation services using consolidated or separate server clusters (i.e., using the same or separate boxes). The rationale is that the mapping service is used in real-time during emergency call routing, while the validation service is used in advance, typically when data is provisioned, and therefore the mapping service has much higher availability and response time requirements than the validation service. An organization might choose to deploy these services using different server clusters to make it easier to provide higher levels of service for the mapping function while shielding it from the potentially bursty load of validation, while another organization might choose to use the same sets of servers for both, configured and deployed to offer the high service level demanded of the mapping service.

In order to permit this separability, any entity querying a LoST server needs to be able to resolve an Application Unique String (AUS) into a URL for a server that offers the required service (mapping or validation). This separability needs to be maintained throughout the LoST tree structure, from forest guide to leaf node. Because LoST referrals return an AUS rather than a URL, different Service Tags are needed for the different services. This document adds 'LoST-Validation' to the S-NAPTR Application Service Tag registry created by [RFC3958]. The 'LoST-Validation' tag serves as a counterpart to the 'LoST' tag added by [RFC4848]: The 'LoST' tag identifies servers able to perform the core mapping function, while 'LoST-Validation' identifies servers explicitly willing to perform the validation function.

Because some servers might be configured to provide both mapping and validation functions, a server identified using the 'LoST' service tag might also perform the validation function (and resolving the two tags might result in the same URL). Because the two functions might be separate, clients seeking a LoST server for location validation should first try U-NAPTR resolution using the 'Lost-Validation' service tag, and may fallback to the 'LoST' service tag if the 'Lost-Validation' service tag cannot be resolved to a usable LoST server.

3. The LoST-Validation Application Service Tag

LoST [RFC4848] specifies that LoST servers are located by resolving an application Unique String (AUS) using U-NAPTR/DDDS (URI-Enabled NAPTR/Dynamic Delegation Discovery Service) [RFC4848], and defines the 'LoST' Application service tag. In order to permit separability of the mapping and validation services performed using LoST, this document defines the 'LoST-Validation' service tag. NAPTR records for LoST servers available for location validation contain the 'LoST-Validation' service tag. An entity needing to perform location validation using LoST performs the discovery procedure as described in [RFC4848], except that the 'LoST-Validation' service tag is used in preference to the 'LoST' service tag. For both service tags, the HTTP and HTTPS URL schemes are used. In the absense of any NAPTR records containing the 'LoST-Validation' service tag, the 'LoST' service tag is used. Fallback to the 'LoST' service tag may follow if the 'Lost-Validation' service tag fails to result in a usable LoST server. Using the 'LoST-Validation' service tag might result in the same URL as the 'LoST' service tag, or it may result in a different URL. The URLs might result in the same physical servers being contacted, or different servers.

4. Security Considerations

The security considerations described in [RFC3958] and [RFC4848] apply here. No additional security aspects are foreseen by the addition of an extra tag. Separation of services might be desired, for example, to be able to allocate different levels of resources (such as server capacity, attack mitigation, bandwidth, etc.) to the mapping and validation services, in which case separate tags are needed to allow LoST clients (which may include other LoST servers) to identify the correct server cluster.

5. IANA Considerations

IANA is requested to add 'LoST-Validation' to the S-NAPTR Application Service Tag registry created by [RFC3958] This tag serves as a counterpart to the 'LoST' tag added by [RFC5222].

(Note that IANA and [RFC3958] call this registry "S-NAPTR Application Service Tags" while [RFC5222] calls it "U-NAPTR application service tag".)

5.1. S-NAPTR Registration

This document registers an S-NAPTR application service tag:

• Application Service Tag: LoST-Validation
• Defining Publication: This document.

6. Acknowledgements

Many thanks to Ted Hardie for his helpful review and suggestions.

7. Changes from Previous Versions

7.1. Changes from -00 to -01

• Fixed incorrect tag in Section 5
• Clarified background and explanation in Section 2
• Clarified text in Section 3
• Expanded text in Section 4

7.2. Changes from -01 to -02

• Fixed bug in .xml file

7.3. Changes from -02 to -03

• Reworded fallback text in Section 2

8. References

8.1. Normative References

8.2. Informative references

Authors' Addresses