DRINKS S. Channabasappa, Ed. Internet-Draft CableLabs Intended status: InformationalMayOctober 25, 2010 Expires:November 26, 2010April 28, 2011 DRINKS Use cases and Protocol Requirementsdraft-ietf-drinks-usecases-requirements-03draft-ietf-drinks-usecases-requirements-04 Abstract This document captures the use cases and associated requirements for interfaces that provision session establishment data into SIP Service Provider components, to assist with session routing. Specifically, the current version of this document focuses on the provisioning of one such element, termed the registry. Status of this Memo This Internet-Draft is submitted to IETF 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 onNovember 26, 2010.April 28, 2011. Copyright Notice Copyright (c) 2010 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 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Registry Use Cases . . . . . . . . . . . . . . . . . . . . . . 9 3.1. Category: Provisioning Mechanisms . . . . . . . . . . . . 9 3.2. Category: Interconnect Schemes . . . . . . . . . . . . . . 9 3.3. Category: SED Exchange and Discovery Models . . . . . . . 11 3.4. Category: SED Record Content . . . . . . . . . . . . . . . 12 3.5. Category: Separation and Facilitation of Data Management . . . . . . . . . . . . . . . . . . . . . . . . 12 3.6. Category: Lookup Keys . . . . . . . . . . . . . . . . . . 13 3.7. Category:Number PortabilityMisc . . . . . . . . . . . . . . . . . . . . . . 143.8. Category: Misc4. Requirements . . . . . . . . . . . . . . . . . . . . . .14 4. Requirements. . . 16 4.1. Provisioning Mechanisms . . . . . . . . . . . . . . . . . 16 4.2. Interconnect Schemes . . . . . . . . . . . . . . . . . . . 16 4.3. SED Exchange and Discovery Requirements . . . . . . . . . 16 4.4. SED Record Content Requirements . . . . . . . . . . . . . 17 4.5. Data Management Requirements . . . . . . . . . . . . . . . 17 4.6. Lookup Key Requirements . . . . . . . . . . . . . . . . . 18 4.7. Misc. Requirements . . . . . . . . . . . . . . . . . . . . 18 5. Security Considerations . . . . . . . . . . . . . . . . . . .1820 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . .1921 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .2022 8. References . . . . . . . . . . . . . . . . . . . . . . . . . .2123 8.1. Normative References . . . . . . . . . . . . . . . . . . .2123 8.2. Informative References . . . . . . . . . . . . . . . . . .2123 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . .2224 1. Terminology 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]. This document reuses terms from [RFC3261] (e.g.,SIP),SIP, SSP), [RFC5486] (e.g., LUF, LRF, SED) and [RFC5067] (carrier-of-record and transit provider). In addition, this document specifies the following additional terms. Registry: The authoritative source for provisioned session establishment data (SED) and related information.RegistrarA Registry can be part of an SSP as well as an independent entity. Registrar: An entity that provisions and manages data into the registry.RegistrantAnentity whose data is provisioned into the registry. The registrantSSP can act as its own registrar or - additionally or alternatively - delegate this function to a third party who acts as its registrar. Local Data Repository: The data store component of an addressing server that provides resolution responses. Public Identifier: A public identifier refers to a telephone number (TN),an emaila SIP address, or other identity as deemed appropriate, such as a globally routable URI of a user address (e.g.,mailto:john.doe@example.net).sip:john.doe@example.net). TN Range: A numerically contiguous set (or, in the case of an open numbering plan, a prefix) of telephone numbers whose SED can be looked up (resolved). RN: A Routing Number. See [RFC4694] for details Destination Group: An aggregation of a set of public identifiers, TN Ranges, or RNs that share commonSED.SED which is exposed to a common set of peers. Data Recipient: An entity with visibility into a specific set of public identifiers, the destination groups that contain these public identifiers, and aroutingroute group's SED records.RoutingRoute Group: An aggregation that contains a related set of SED records, and is associated with a set of destination groups.RoutingRoute groups facilitate the management of SED records- which are common to a large number of public identifiers, TN Ranges or RNs -for one or more data recipients. 2. Overview The SPEERMINT WG specifies Session Establishment Data, or SED, as the data used to route a call to the next hop associated with the called domain's ingress point. More specifically, the SED is the set of parameters that the outgoing signaling path border elements (SBEs) need to establish a session. See Section 3.3 of [RFC5486] for more details. The specification of the format and protocols to provision SED is a task taken up by the DRINKS WG. This document contains the use cases and requirements that have been proposed in this regard. SED is typically created by the terminating or next-hop SSP and consumed by the originating SSP. To avoid a multitude of bilateral exchanges, SED is often shared via intermediary systems - termed registries within this document. Such registries receiveSEDdata via provisioning transactions fromotherSSPs, and then distribute the received data into Local Data Repositories. These local data repositories are used for call routing by outgoing SBEs. This is depicted in Figure 1. *-------------* 1. Provision SED | | -----------------------> | Registry | | | *-------------* / \ / \ / \ / \ / \ / \ / 2.Distribute \ / SED \ V V +----------+ +----------+ |Local Data| |Local Data| |Repository| |Repository| +----------+ +----------+ Figure 1: General Diagram In thisversion of thedocument, we primarily address the use cases and requirements for provisioning registries. Future revisions may include data distribution to local data repositories. The resulting provisioning protocol can be used to provision data into a registry, or betweenregistries. This is depictedmultiple registries operating in parallel. In Figure2.2, the case of multiple registries is depicted with dotted lines. . . . . . . . . . . . . . . registry . . . . . . . . . . . . . . . . . . . . . . . . provision . +-----------+ . +-----------+ | | provision +----------+ provision | | | SSP 1 |------------>| Registry |<-----------| SSP 2 | | | +----------+ | | | +-----+ | /\ | +-----+ | | | LDR | <-------------------- ------------------>| LDR | | | +-----+ | distribute distribute | +-----+ | | | | | +-----------+ +-----------+ . . . . . . . . . . . . . . . . . . . . . . . . . . (provision / distribute) Where, LDR = Local Data Repository Figure 2: Functional Overview In addition, this document proposes the following aggregation groups with regards to SED (refer to the use cases in Section 3.5 for the rationale): o Aggregation of public Identifiers into a destination group. o Aggregation of SED records into aRoutingRoute Group. The data model depicted in Figure 3 shows the various entities, aggregations and the relationships between them. +---------+ +--------------+ +---------+ | Data |0..n 0..n|ROUTINGROUTE | 1 0..n| SED | |Recepient|------------| GROUP | --------------| Record | +---------+ +--------------+ +---------+ |0..n |0..n | | | | | | |0..n | 1 +--------------+ 0..1 | ---------| DESTINATION |--------- | | | GROUP | | | | +--------------+ | | | | | | | 1| | | | | | | | | | | 0..n | 0..n | | 0..n | +---------+ +---------+ +----------+ | | RN | | TN | | Public |---- | | | Range | |Identifier| 1 +---------+ +---------+ +----------+ Figure 3: Data Model Diagram The relationships are as described below: - AData RecipientPublic Identifier object can beassociated withdirectly related to zero or moreRouting GroupSED Record objects, and aRouting GroupSED Record object canreferbe related tozero or more Data Recipient objects.exactly one Public Identifier object. - ARoutingDestination Group object can contain zero or moreSED RecordTN Range objects, and aSED RecordTN Range object can be contained in exactly oneRoutingDestination Group object. - ARoutingDestination Group object canbe associated withcontain zero or moreDestination GroupPublic Identifier objects, and aDestination GroupPublic Identifier object can beassociated with zero or more Routingcontained in exactly one Destination Groupobjects.object. - A Destination Group object can contain zero or more RN objects, and an RN object can be contained in exactly one Destination Group object. - ADestinationRoute Group object can contain zero or moreTN RangeSED Record objects, and aTN RangeSED Record object can be contained in exactly oneDestinationRoute Group object. - ADestinationRoute Group object cancontainbe associated with zero or morePublic IdentifierDestination Group objects, and aPublic IdentifierDestination Group object can becontained in exactly one Destinationassociated with zero or more Route Groupobject.objects. - A Data Recipient object can be associated with zero or more Route Group objects, and a Route Group object can refer to zero or more Data Recipient objects. 3. Registry Use Cases This Section documents use cases related to the provisioning of the registry. Any request to provision, modify or delete data is subject to authorization. However, the act of authorization is considered to be out of scopewithinof this document. 3.1. Category: Provisioning Mechanisms UC PROV #1 Real-Time Provisioning: Registrars have operational systems that provision public identifiers, in association with their SED. These systems often function in a manner that expect or require that these provisioning activities be completed immediately, as apposed to an out-of-band or batch provisioning scheme that can occur at a later time. This type of provisioning is referred to as real-time, or on-demand provisioning. UC PROV #2 Non-Real-Time Bulk Provisioning: Operational systems that provision public identifiers and associated SED sometimes expect that these provisioning activities be batched up into large sets. These batched requests are then processed using a provisioning mechanism that is out-of- band and occurs at a later time. UC PROV #3 Multi-Request Provisioning: Regardless of whether a provisioning action is performed in real-time or not, SSPs often perform several provisioning actions on several objects in a single request or transaction. This is done for performance and scalability reasons, and for transactional reasons, such that the set of provisioning actions either fail or succeed atomically, as a complete set. 3.2. Category: Interconnect Schemes UC INTERCONNECT #1 Inter-SSP SED: SSPs create peering relationships with other SSPs in order to establish interconnects. Establishing these interconnects involves, among other things, communicating and enabling the points of ingress and other SED used to establish sessions to a set of public identifiers. UC INTERCONNECT #2 Direct vs Indirect Peering: Some inter-SSP peering relationships are created to enable the establishment of sessions to the public identifiers for which an SSP is the carrier-of- record. This is referred to as direct peering. Other inter-SSP peering relationships are created to enable the establishment of sessions to public identifiers for which an SSP is a transit provider. This is referred to as indirect peering. Some SSPs take into consideration an SSP's role as a transit or carrier-of-record provider when selecting a route to a public identifier. UC INTERCONNECT #3 Intra-SSP SED: SSPs support the establishment of sessions between their own public identifiers, not just to otherSSPsSSPs' public identifiers. Enabling this involves, among other things, communicating and enabling intra-SSP signaling points and other SED that can differ from inter- SSP signaling points and SED. UC INTERCONNECT #4 Selective Peering (a.k.a. per peer policies): SSPs create peering relationships with other SSPs in order to establish interconnects. However, SSPs peering relationships often result in different points of ingress or other SED for the same set of public identifiers. UC INTERCONNECT #5 Provisioning of a delegatedname server:hierarchy: An SSPmaintains a Tier 2 name server that containsmay decide to maintain its own infrastructure to contain theNAPTRroute records thatconstituteconstitue the terminal step in the LUF.TheIn such cases, the SSPneeds towill provisiona registryregistries to direct queries for the SSP'snumbers to the Tier 2 name server. Usually queriespublic identifiers to its own infrastructure, rather than provisioning theregistry should return NS records, butroute records directly. For example, incases wheretheTier 2 usescase of DNS-based route records, such adifferent domain suffix from that used in the registry, CNAME anddelegated hierarchy would make use of NSrecords may be employed instead.and CNAME records, while a flat structure would make use of NAPTR resource records. 3.3. Category: SED Exchange and Discovery Models UC SED EXCHANGE #1 SED Exchange and Discovery using unified LUF/LRF: When establishing peering relationships some SSPs may wish to communicate or receive SED (e.g., points ofingress and other SEDingress) thatcontainconstitutes the aggregated result of both LUF and LRF. UC SED EXCHANGE #2 SED Exchange and Discovery using LUF's Domain Name: When establishing peering relationships some SSPs may not wish to communicate or receive points of ingress and other SED using a registry. They wish to only communicate or receive domain namesresolvable via [RFC3263],(LUF step only), andthis query willthenreturnindependently resolvable those domain names via [RFC3263] to the final points of ingressordata (and otherSED that form the LUF.SED). UC SED EXCHANGE #3 SED Exchange and Discovery using LUF's Administrative Domain Identifier: When establishing peering relationships some SSPs may not wish to communicate or receive points of ingress and other SED using a registry. They wish to only communicate or receive an administrative domain identifier, which is not necessarily resolvable via DNS. The subsequent process of using that administrative domain identifier to select points of ingress or other SED can be SSP specific and occurs outside the context of this protocol. UC SED EXCHANGE #4 Co-existent SED Exchange and Discovery Models: When supporting multiple peering relationships some SSPs have the need to concurrently support all three of the SED Exchange and Discovery Models described above, for the same set oflookup keys.Public Identifiers. 3.4. Category: SED Record Content UC SED RECORD #1 SED Record Content: Establishing interconnects between SSPs involves, among other things, communicating points of ingress, the service types (SIP, SIPS, etc) supported by each point of ingress, and the relative priority of each point of ingress for each service type. UC SED RECORD #2 Time-To-Live (TTL): For performance reasons, querying SSPs sometimes cache SED that had been previously looked up for a given public identity. In order to accomplish this, SSPs sometimes specify the TTL associated with a given SED record. 3.5. Category: Separation and Facilitation of Data Management UC DATA #1 Separation of Provisioning Responsibility: An SSP's operational practices often separate the responsibility of provisioning the points of ingress and other SED, from the responsibility of provisioning public identifiers (or TN ranges or RNs). For example, a network engineer can establish a physical interconnect with a peering SSP's network and provision the associated domain name, host, and IP addressing information. Separately, for each new subscriber, the SSP's provisioning systemsprovisionsprovision the associated public identifiers. UC DATA #2 Destination Groups: SSPs often provision identical SED for large numbers of public identifiers.GroupsFor reasons of efficiency, groups of public identifiers that have the same SED can be aggregated. These aggregations arecreated. This grouping is knowknown asDestination Group.destination groups. The SED is then indirectly associated withthat groupdestination groups rather thantowith each individual public identity. UC DATA #3 Route Groups: SSPs often provision identical SED for large numbers of public identifiers, and then expose that relationship between a group of SED records and a group of public identifiers to one or more SSPs. This combined grouping of SED records and Destination Groups facilitates management of public identity SED relationships and the list of peers (data recipients) that can lookup those public identifiers and receive that SED. This dual set of SED Records and Destination Groups is termed as a Route Group. 3.6. Category: Lookup Keys UC LOOKUP #1 Additions and deletions: SSPs often allocate and de- allocate specific public identifiers to and from end- users. This involves, among other things, activating or deactivating specific public identifiers (or TN ranges or RNs), and directly (or indirectly) associating them with the appropriate points of ingress and other SED. UC LOOKUP #2 Carrier-of-Record vs Transit Lookup Key Provisioning: Some inter-SSP peering relationships are created to enable the establishment of sessions to the lookup keys for which an SSP is the carrier-of-record. Other inter-SSP peering relationships are created to enable the establishment of sessions to lookup keys for which an SSP is a transit provider. Some SSPs take into consideration an SSP's role as a transit or carrier-of- record provider when selecting a route to a public identifier. UC LOOKUP #3 Multiplicity of Identical Lookup Keys: As described in previous use cases, SSPs provision lookup keys and their associated SED for multiple peering SSPs, and as both the carrier-of-record and transit provider. As a result, a given lookup key can reside in multiple destination groups at any given time. UC LOOKUP #4 Lookup Key Destination Group Modification: SSPs often change the SED associated with a given lookup key. This involves, among other things, directly or indirectly associating them with a different point of ingress, different services, and/or different other SED. UC LOOKUP #5 Lookup Key Carrier-Of-Record vs Transit Modification: SSPs may have the need to change their Carrier-Of- Record vs Transit role for lookup keys they previously provisioned. UC LOOKUP #6 Modification of authority: An SSP indicates that it is the carrier-of-record for an existing public identity or TN Range. If the public identity or TN Range was previously associated with a different carrier-of- record then there are multiple possible outcomes, such as: a) the previous carrier-of-record is disassociated, b) the previous carrier-of-record is relegated to transit status, or c) the new carrier-of-record is placed in inactive mode. The choice may be dependent on the deployment scenario, and is out of scope for this document. 3.7. Category:Number PortabilityMisc UCNPMISC #1EDITOR's NOTE: Need to clarify this further.The SSP wishes toprovideprovide, in query response to publicidentifiersidentifiers, an associated routing numberor RN.(RN). This is the casewhenwhere a set of public identifiers is no longer associated with original SSP but have been ported to a recipientSSPSSP, who provides access to these identifiers via a switch on the SS7 network identified by the RN.In this case a destination group containing all numbers that should be routed to this RN needs to be created and the route group associated with this DG needs to contain the RN 3.8. Category: MiscUC MISC#1#2 Data Recipient Offer and Accept: When a peering relationship is established (or invalidated) SSPs provision (or remove) data recipients in the registry. However, a peer may first need to accept it's role (as a data recipient) before such a change is made effective. Alternatively an auto-accept feature can be configured for a given data recipient. UC MISC#2#3 Open numbering plans: In several countries, an"openopen numberingplan"plan is used, which issuch thatwhere thecarrier- of-record doescarrier-of- record is only aware of a portion of the E.164 number (i.e., the prefix). The carrier-of-record may notin factknow the complete number,but instead only knows a portionor the number of digits in theE.164number. The rest of the digits are handled offline (e.g., by aPBX off of that carrier-of-record, and even the number of those digit is not fixed.PBX). For example, an SSP can be thecarrier-of- recordcarrier-of-record for "+123456789", and is also thecarrier-of- recordcarrier-of-record for every possible expansion of that number such as "+12345678901" and "+123456789012", even though the SSP does not know what those expansions couldbe, because the PBX decides that.be. This can be described as the carrier-of-record effectively being authoritative fora "prefix".the prefix. 4. Requirements This Section lists the requirements based on the use cases in Section 3. Unless explicitly stated as optional, the registry provisioning interface must support these requirements.REQ1: a) Real-time, b) non-real-time bulk, and c) multi-request4.1. Provisioning Mechanisms REQ-PROV-1: Real-time provisioning. REQ-PROV-2: Non-real-time bulk provisioning.REQ2:REQ-PROV-3: Multi-request provisioning. 4.2. Interconnect Schemes REQ-INTERCONNECT-1: Inter-SSPSED with support for directpeering. REQ-INTERCONNECT-2: Direct andindirectIndirect peering.REQ3:REQ-INTERCONNECT-3: Intra-SSP SED.REQ4:REQ-INTERCONNECT-4: Selective peering.REQ5:REQ-INTERCONNECT-5: Provisioning of a delegatedname server. REQ6: The followinghierarchy. 4.3. SED Exchange anddiscovery models (concurrently for the same public identifier): a)Discovery Requirements REQ-SED-1: SED containing unifiedLUF/LRF, b) LUF- only with domain name,LUF andc)LRF content. REQ-SED-2: SED containing LUF-onlywithdata using domain names. REQ-SED-3: SED containing LUF-only data using administrativedomain. REQ7: Provisioning ofdomains. REQ-SED-4: Support for all the other REQ-SED requirements, concurrently, for the same public identifier. 4.4. SED Recordcontent REQ8:Content Requirements REQ-SED-RECORD-1: Ability to provision SED record content. REQ-SED-RECORD-2: (Optional)Communicate theCommunication of an associated TTL for agivenSED Record.REQ9:4.5. Data Management Requirements REQ-DATA-MGMT-1: Separation of responsibilityoffor the provisioning the points of ingress and other SED, from the responsibility of provisioning public identifiers.REQ10: Additions and deletionsREQ-DATA-MGMT-2: Ability to aggregate a set of publicidentifiers, TN ranges and RNs. REQ11:identifiers as destination groups. REQ-DATA-MGMT-3: Ability to create the aggregation termed route group. 4.6. Lookup Key Requirements REQ-LOOKUP-1: Provisioning of, and modifications to, the following aggregations: destination group and route groups.REQ12: Support the distinction betweenREQ-LOOKUP-2: Ability to distinguish an SSP asa carrier-of-recordeither the carrier- of-record providerversusor transit provider.REQ13: Support forREQ-LOOKUP-3: A given lookupkeys having identical business keys (thekey (e.g., publicidentity string, the digits that comprise anidentity, RN,the start and end point of aTNrange's range) that concurrently exist acrossRange) can reside in multiple destination groupsand where each destination group may be managed by different SSPs. Editor's note: We need to simplifyat theabove requirement. REQ14:same time. REQ-LOOKUP-4: Modification of lookup keys by allowing them to be moved to a different destination group via an atomic operation.REQ15:REQ-LOOKUP-5: SSPstocan indicate a change to theirCarrier-Of- Record vs Transit role. REQ16:role from carrier- of-record provider to transit, or vice-versa. REQ-LOOKUP-6: Support for modification of authority with the conditions described in UC LOOKUP #6.REQ17: Destination group offer4.7. Misc. Requirements REQ-MISC-1: Number portability support. REQ-MISC-2: Ability for the SSP to be offered a peering relationship, andacceptance (optionally support auto-acceptance). REQ18: Openfor the SSP to accept (explicitly or implicitly) or reject such an offer. REQ-MISC-3: Support for open numbering plans. 5. Security Considerations Session establishment data allows for the routing of SIP sesions within, and between, SIP Service Providers. Access to this data can compromise the routing of sessions and expose a SIP Service Provider to attacks such as service hijacking and denial of service. The data can be compromised by vulnerable functional components and interfaces identified within the use cases. A provisioning protocol or interface that implements the described use cases MUST therefore provide data confidentiality, and MUST ensure message integrity for the provisioning flow. Authentication and authorization of the provisioning entities are REQUIRED features of the protocol and interfaces. 6. IANA Considerations This document does not register any values in IANAregistries.registries, nor request the creation of a registry. 7. Acknowledgments This document is a result of various discussions heldbywithin the DRINKSrequirements design team, which is comprised of the following individuals,WG; specifically , in alphabetical order: Alexander Mayrhofer, Deborah AGuyton (Telcordia),Guyton, GregorySchumacher (Sprint),Schumacher, Jean-FrancoisMule (CableLabs),Mule, KennethCartwright (TNS, Inc.),Cartwright, ManjulMaharishi (TNS, Inc.),Maharishi, PennPfautz (AT&T Corp),Pfautz, RayBellis (Nominet), the co-chairs (RichardBellis, Richard Shockey,Nuestar; and Alexander Mayrhofer, enum.at GmbH),andthe editors of this document.Syed Ali. This specific version of the document is a result of contributionsfrom, primarily, David Schwartz (XConnect), Kenneth Cartwright (TNS, Inc.) and Syed Ali (Neustar, Inc.). Other participants who reviewed and provided comments include:from the following individuals: AlexanderMayrhofer (enum.at GmbH), Jean-Francois Mule (CableLabs), Manjul Maharishi (TNS, Inc.), Hadriel Kaplan (Acme Packet)Mayrhofer, Otmar Lendl, Sohel Khan, andother participants on the DRINKS mailing list.Peter Koch. In addition, we also thank Brian Rose and Jon Peterson for suggestions we incorporated. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5486] Malas, D. and D. Meyer, "Session Peering for Multimedia Interconnect (SPEERMINT) Terminology", RFC 5486, March 2009. 8.2. Informative References [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP): Locating SIP Servers", RFC 3263, June 2002. [RFC4694] Yu, J., "Number Portability Parameters for the "tel" URI", RFC 4694, October 2006. [RFC5067] Lind, S. and P. Pfautz, "Infrastructure ENUM Requirements", RFC 5067, November 2007.[RFC5486] Malas, D. and D. Meyer, "Session Peering for Multimedia Interconnect (SPEERMINT) Terminology", RFC 5486, March 2009.Author's Address Sumanth Channabasappa CableLabs 858 Coal Creek Circle Louisville, CO 80027 USA Email: sumanth@cablelabs.com