One document matched: draft-wu-pce-dns-pce-discovery-02.xml


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<rfc category="std" docName="draft-wu-pce-dns-pce-discovery-02"
     ipr="trust200902">
  <?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

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  <?rfc strict="yes" ?>

  <front>
    <title abbrev="DNS based PCED">Path Computation Element (PCE) Discovery
    using Domain Name System(DNS)</title>

    <author fullname="Qin Wu" initials="Q." surname="Wu">
      <organization>Huawei</organization>

      <address>
        <postal>
          <street>101 Software Avenue, Yuhua District</street>

          <city>Nanjing</city>

          <region>Jiangsu</region>

          <code>210012</code>

          <country>China</country>
        </postal>

        <email>sunseawq@huawei.com</email>
      </address>
    </author>

    <author fullname="Dhruv Dhody" initials="D." surname="Dhody">
      <organization>Huawei</organization>

      <address>
        <postal>
          <street>Leela Palace</street>

          <city>Bangalore</city>

          <region>Karnataka</region>

          <code>560008</code>

          <country>INDIA</country>
        </postal>

        <email>dhruv.dhody@huawei.com</email>
      </address>
    </author>

    <author fullname="Daniel King" initials="D" surname="King">
      <organization>Old Dog Consulting</organization>

      <address>
        <postal>
          <street></street>

          <city></city>

          <region></region>

          <code></code>

          <country>UK</country>
        </postal>

        <email>daniel@olddog.co.uk</email>
      </address>
    </author>

    <author fullname="Diego R. Lopez " initials="D" surname="Lopez">
      <organization>Telefonica I+D</organization>

      <address>
        <postal>
          <street></street>

          <city></city>

          <region></region>

          <code></code>

          <country></country>
        </postal>

        <email>diego@tid.es</email>
      </address>
    </author>

    <date year="2013" />

    <area>Routing Area</area>

    <workgroup>PCE Working Group</workgroup>

    <keyword>RFC</keyword>

    <keyword>Request for Comments</keyword>

    <keyword>I-D</keyword>

    <keyword>Internet-Draft</keyword>

    <keyword>Path Computation Element</keyword>

    <abstract>
      <t>Discovery of the Path Computation Element (PCE) within an IGP area or
      routing domain is possible using OSPF [RFC5088] and IS-IS [RFC5089].
      However, in some deployment scenarios PCEs may not wish, or be able, to
      participate within the IGP process, therefore it would be beneficial for
      the Path Computation Client (PCC) (or other PCEs) to discover PCEs via
      an alternative mechanism to those proposed in [RFC5088] and
      [RFC5089].</t>

      <t>This document specifies the requirements, use cases, procedures and
      extensions to support discovery via DNS for PCE.</t>
    </abstract>
  </front>

  <middle>
    <section anchor="intro" title="Introduction">
      <t>The Path Computation Element Communication Protocol (PCEP) is a
      transaction-based protocol carried over TCP [RFC4655]. In order to be
      able to direct path computation requests to the Path Computation Element
      (PCE), a Path Computation Client (PCC) (or other PCEs) needs to know the
      location and capability of a PCE.</t>

      <t>In a network where an IGP is used and where the PCE participates in
      the IGP, discovery mechanisms exist for PCC (or PCE) to learn the
      identity and capability of each PCE. [RFC5088] defines a PCE Discovery
      (PCED) TLV carried in an OSPF Router LSA. Similarly, [RFC5089] defines
      the PCED sub-TLV for use in PCE Discovery using IS-IS. Scope of the
      advertisement is limited to IGP area/level or Autonomous System
      (AS).</t>

      <t>However in certain scenarios not all PCEs will participate in the IGP
      instance, section 3 (Motivation) outlines a number of use cases. In
      these cases, current PCE Discovery mechanisms are therefore not
      appropriate and another PCE discovery function would be required.</t>

      <t>This document describes PCE discovery via DNS. The mechanism with
      which DNS comes to know about the PCE and its capability is out of scope
      of this document.</t>

      <section title="Terminology" toc="default">
        <t>The following terminology is used in this document.</t>

        <t><list style="hanging">
            <t hangText="Domain:">As per <xref target="RFC4655"></xref>, any
            collection of network elements within a common sphere of address
            management or path computational responsibility. Examples of
            domains include Interior Gateway Protocol (IGP) areas and
            Autonomous Systems (ASs).</t>

            <t hangText="Domain-Name:">TBD.</t>
          </list></t>
      </section>

      <section title="Requirements">
        <t>As described in [RFC4674], the PCE Discovery information should at
        least be composed of: <list style="symbols">
            <t>The PCE location: an IPv4 and/or IPv6 address that is used to
            reach the PCE. It is RECOMMENDED to use an address that is always
            reachable if there is any connectivity to the PCE;</t>

            <t>The PCE path computation scope (i.e., intra-layer, inter-area,
            inter-AS, or inter-layer);</t>

            <t>The set of one or more PCE-Domain(s) into which the PCE has
            visibility and for which the PCE can compute paths;</t>

            <t>The set of zero, one, or more neighbor PCE-Domain(s) toward
            which the PCE can compute paths;</t>
          </list></t>

        <t>that allows PCCs to select appropriate PCEs:</t>

        <t>This document specifies an extension to DNS for the above PCE
        information discovery, which is complements the existing discovery
        mechanism.</t>
      </section>
    </section>

    <section title="Conventions used in this document">
      <t>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 <xref
      target="RFC2119">RFC2119</xref>.</t>
    </section>

    <section title="Motivation">
      <t>This section discusses in more detail the motivation and use cases
      for an alternative DNS based PCE discovery mechanism.</t>

      <section title="Outside the Routing Domain">
        <t>When the PCE is a router participating in the Interior Gateway
        Protocol (IGP), or even a server participating passively in the IGP,
        with all PCEP speakers in the same routing domain, a simple and
        efficient way to announce PCEs consists of using IGP flooding.</t>

        <t>But the existing mechanism does not work in following
        situations:</t>

        <t><list style="hanging">
            <t hangText="Inter-AS:">Per domain path computation mechanism
            [RFC5152] or Backward recursive path computation (BRPC) [RFC5441]
            MAY be used by cooperating PCEs to compute inter-domain path. In
            which case these cooperating PCEs should be known to other PCEs.
            In case of inter-AS where the PCEs do not participate in a common
            IGP, the existing IGP discovery mechanism cannot be used to
            discover inter-AS PCE.</t>

            <t hangText="Hierarchy of PCE:">The H-PCE [RFC6805] architecture
            does not require disclosure of internals of a child domain to the
            parent PCE. It may be necessary for a third party to manage the
            parent PCEs according to commercial and policy agreements from
            each of the participating service providers [PCE-QUESTION]. <xref
            target="RFC6805"></xref> specifies that a child PCE must be
            configured with the address of its parent PCE in order for it to
            interact with its parent PCE. However handling changes in parent
            PCE identities and coping with failure events would be an issue
            for a configured system. There is no scope for parent PCEs to
            advertise their presence to child PCEs when they are not a part of
            the same routing domain.</t>

            <t hangText="BGP:">[I.D.draft-ietf-idr-ls-distribution] describes
            a mechanism by which links state and traffic engineering
            information can be collected from networks and shared with
            external components using the BGP routing protocol. An external
            PCE MAY use this mechanism to populate its TED and not take part
            in the same IGP routing domain.</t>

            <t hangText="NMS/OSS:">PCE server MAY gain the knowledge of
            Topology information from some management system (e.g.,NMS/OSS)
            and not take part in the same routing domain. Also note that in
            some case PCC may not be a router and instead be a management
            system like NMS and may not be able to discover PCE via IGP
            discovery.</t>
          </list></t>
      </section>

      <section title="Query-Response v/s Advertisement">
        <t>Advertisement based IGP PCE discovery [RFC5088] and [RFC5089]
        floods the PCE information to an area, a subset of areas or to a full
        routing domain. By the very nature of flooding and advertisements it
        generates unwanted traffic and may lead to unnecessary advertisement,
        especially when PCE information needs frequent changes.</t>

        <t>DNS is a query-response based mechanism, a client (say PCC) can use
        DNS to discover a PCE only when it needs it and does not require any
        other node in the network to be involved.</t>

        <t>Incase of Intermittent PCEP session, where PCEP sessions are
        systematically open and closed for each PCEP request, a DNS based
        query-response mechanism is more suitable. One may utilize DNS based
        load-balancing and recovery functions.</t>
      </section>

      <section title="Network Address Translation Gateway">
        <t>PCEP uses TCP as the transport [RFC5440]. To secure TCP connection
        that underlay PCEP sessions, TLS can be used besides using TCP-MD5
        [RFC2385] and TCP-AUTH [RFC5295]. When PCC and PCE support TCP-MD5 or
        TCP-AUTH while NAT does not, TCP connection establishment fails. When
        NAT gateway is in presence, a TCP or TCP/TLS connection can be opened
        by Interactive Connectivity Establishment (ICE) [RFC5245] for the
        purpose of connectivity checks. However the TCP connection cannot be
        established in cases where one of the peers is behind a NAT with
        connection-dependent filtering properties [RFC5382]. Therefore IGP
        discovery is limited within an IGP domain and cannot be used in this
        case.</t>
      </section>
    </section>

    <section title="Other Considerations">
      <section title="Load Sharing of Path Computation Requests">
        <t>Multiple PCE servers can be present in a single network domain for
        redundancy. DNS supports inherent load balancing where multiple PCEs
        (with different IP addresses) are known in DNS for a single PCE server
        name and are hidden from the PCC.</t>

        <t>In an IGP advertisement based PCE discovery, one learns of all the
        PCEs and it is the job of the PCC to do load-balancing.</t>

        <t>A DNS based load-balancing mechanism works well in case of
        Intermittent PCEP sessions and request are load-balanced among PCEs
        similar to HTTP request without any complexity at the client.</t>
      </section>
    </section>

    <section title="Discovering a Path Computation Element">
      <t>The Dynamic Delegation Discovery System (DDDS) [RFC3401] is used to
      implement lazy binding of strings to data, in order to support
      dynamically configured delegation systems. The DDDS functions by mapping
      some unique string to data stored within a DDDS database by iteratively
      applying string transformation rules until a terminal condition is
      reached. When DDDS uses DNS as a distributed database of rules, these
      rules are encoded using the Naming Authority Pointer (NAPTR) Resource
      Record (RR). One of these rules is the First Well Known Rule, which says
      where the process starts.</t>

      <t>In current specifications, the First Well Known Rule in a DDDS
      application [RFC3403] is assumed to be fixed, i.e., the domain in the
      tree where the lookups are to be routed to, is known. This document
      proposes the input to the First Well Known Rule to be dynamic, based on
      the search path the resolver discovers or is configured to use.</t>

      <t>The search path of the resolver can either be pre-configured, or
      discovered using DHCP.</t>

      <t>When the PCC or other PCEs needs to discover PCEs in the domain into
      which the PCEP speaker has visibility (e.g.,local domain), the input to
      the First Well Known Rule MUST be the domain the PCC knows, which is
      assumed to be pre-configured in the PCC or discovered using DHCP.</t>

      <t>When the PCC needs to discover PCE in the other domain (e.g., AS,
      Parent PCE in the parent domain)into which the PCC has no visibility, it
      SHOULD know the domain name of that domain and use DHCP to discover IP
      address of the PCE in that domain that provides path computation service
      along with some PCE location information useful to a PCC for PCE
      selection, and contact it directly. In some instances, the discovery may
      result in a per protocol/application list of domain names that are then
      used as starting points for the subsequent NAPTR lookups. If neither the
      IP address nor other PCE location information can be discovered with the
      above procedure, the PCC MAY request a domain search list, as described
      in [RFC3397] and [RFC3646], and use it as input to the DDDS
      application.</t>

      <t>When the PCC does not find valid domain names using the procedures
      above, it MUST stop the attempt to discover any PCE.</t>

      <t>The dynamic rule described above SHOULD NOT be used for discovering
      services other than Path computation services described in this
      document, unless stated otherwise by a future specification.</t>

      <t>The procedures defined here result in an IP address, PCE domain,
      neighboring PCE domain and PCE Computation Scope where the PCC can
      contact the PCE that hosts the service the PCC is looking for.</t>

      <section title="Determining the PCE Service and transport protocol">
        <t>The PCC should know the service identifier for the Path Computation
        Discovery service. The service identifier for the Path Computation
        Discovery service is defined as "PCED", The PCE supporting "PCED"
        service MUST support only TCP as transport, as described in
        [RFC5440].</t>

        <t>The services relevant for the task of transport protocol selection
        are those with NAPTR service fields with values "ID+M2X", where ID is
        the service identifier defined in the previous section, and X is a
        letter that corresponds to a transport protocol supported by the
        domain. This specification only defines M2T for TCP. This document
        also establishes an IANA registry for mappings of NAPTR service name
        to transport protocol.</t>

        <t>These NAPTR [RFC3403] records provide a mapping from a domain to
        the SRV [RFC2782] record for contacting a PCE with the specific
        transport protocol in the NAPTR services field. The resource record
        MUST contain an empty regular expression and a replacement value,
        which indicates the domain name where the SRV record for that
        particular transport protocol can be found. As per [RFC3403], the
        client discards any records whose services fields are not
        applicable.</t>

        <t>The PCC MUST discard any service fields that identify a resolution
        service whose value is not "M2T", for values of T that indicate TCP
        transport protocols supported by the client. The NAPTR processing as
        described in RFC 3403 will result in the discovery of the most
        preferred transport protocol of the PCE that is supported by the
        client, as well as an SRV record for the PCE.</t>
      </section>

      <section title="Determining the IP Address of the PCE">
        <t>As an example, consider a client that wishes to find PCED service
        in the example.com domain. The client performs a NAPTR query for that
        domain, and the following NAPTR records are returned: <figure>
            <artwork>
Order Pref Flags  Service     Regexp       Replacement
 IN NAPTR  50   50   "s"  "PCED"    ""   
 _PCED._tcp.example.com
 IN NAPTR  90   50   "s"  "PCED+M2T"    ""  
 _PCED._tcp.example.com
</artwork>
          </figure></t>

        <t>This indicates that the domain does have a PCE providing Path
        Computation services over TCP, in that order of preference. Since the
        client only supports TCP, TCP will be used, targeted to a host
        determined by an SRV lookup of _PCED._tcp.example.com. That lookup
        would return: <figure>
            <artwork>
   ;;  Priority  Weight    Port        Target
IN  SRV    0        1      XXXX   server1.example.com
IN  SRV    0        2      XXXX   server2.example.com
</artwork>
          </figure></t>

        <t>where XXXX represents the port number at which the service is
        reachable.</t>

        <t>Note that the regexp field in the NAPTR example above is empty. The
        regexp field MUST NOT be used when discovering path computation
        services, as its usage can be complex and error prone. Also, the
        discovery of the path computation service does not require the
        flexibility provided by this field over a static target present in the
        TARGET field.</t>

        <t>If the client is already configured with the information about
        which transport protocol is used for a path computation service in a
        particular domain, it can directly perform an SRV query for that
        specific transport using the service identifier of the path
        computation Service. For example, if the client knows that it should
        be using TCP for path computation service, it can perform a SRV query
        directly for_PCED._tcp.example.com.</t>

        <t>Once the server providing the desired service and the transport
        protocol has been determined, the next step is to determine the IP
        address.</t>

        <t>According to the specification of SRV RRs in [RFC2782], the TARGET
        field is a fully qualified domain name (FQDN) that MUST have one or
        more address records; the FQDN must not be an alias, i.e., there MUST
        NOT be a CNAME or DNAME RR at this name. Unless the SRV DNS query
        already has reported a sufficient number of these address records in
        the Additional Data section of the DNS response (as recommended by
        [RFC2782]), the PCC needs to perform A and/or AAAA record lookup(s) of
        the domain name, as appropriate. The result will be a list of IP
        addresses, each of which can be contacted using the transport protocol
        determined previously.</t>
      </section>

      <section title="Determining path computation scope,capability,the PCE domains and Neighbor PCE domains">
        <t>DNS servers MAY use DNS TXT record to give additional information
        about PCE service and add TXT record to the additional information
        section that are relevant to the answer and have the same authenticity
        as the data (Generally this will be made up of A and SRV records)in
        the answer section. The additional information includes path
        computation scope, capability, the PCE domains and Neighbor PCE
        domains associated with the PCE. the PCC MAY inspect those Additional
        Information section and be capable of handling responses from
        nameservers that never fill in the Additional Information part of a
        response.</t>
      </section>

      <section title="Relationship between PCE-Domain and DNS Domain-Name">
        <t>As per [RFC4655], PCE-Domain is a collection of network elements
        within a common sphere of address management or path computational
        responsibility. Examples of PCE-domains include Interior Gateway
        Protocol (IGP) areas and Autonomous Systems (ASs). The DNS domain-name
        should have a mechanism to link the IGP area or AS to the DNS
        namespace.</t>

        <t>Editors Note - To be discussed further</t>
      </section>
    </section>

    <section title="IANA Considerations">
      <t>The usage of NAPTR records described here requires well-known values
      for the service fields for the transport supported by Path Computation
      Services. The table of mappings from service field values to transport
      protocols is to be maintained by IANA.</t>

      <t>The registration in the RFC MUST include the following
      information:<figure>
          <artwork>
Service Field: The service field being registered.

Protocol: The specific transport protocol associated with that
service field.  This MUST include the name and acronym for the
protocol, along with reference to a document that describes the
transport protocol.

Name and Contact Information: The name, address, email address,
and telephone number for the person performing the registration.
</artwork>
        </figure></t>

      <t>The following values have been placed into the registry:<figure>
          <artwork>
Service Fields                    Protocol
   PCED+M2T                        TCP
</artwork>
        </figure></t>

      <t>New Service Fields are to be added via Standards Action as defined in
      [RFC5226].</t>

      <t>IANA is also requested to register PCED as service name in the
      Protocol and Service Names registry.</t>
    </section>

    <section title="Security Considerations">
      <t>It is believed that this proposed DNS extension introduces no new
      security considerations (i.e., A list of known threats to services using
      DNS) beyond those described in [RFC3833]. For most of those identified
      threats, the DNS Security Extensions [RFC4033] does provide protection.
      It is therefore recommended to consider the usage of DNSSEC [RFC4033]
      and the aspects of DNSSEC Operational Practices [RFC6781] when deploying
      Path Computation Services.</t>

      <t>In deployments where DNSSEC usage is not feasible, measures should be
      taken to protect against forged DNS responses and cache poisoning as
      much as possible. Efforts in this direction are documented in
      [RFC5452].</t>

      <t>Where inputs to the procedure described in this document are fed via
      DHCP, DHCP vulnerabilities can also cause issues. For instance, the
      inability to authenticate DHCP discovery results may lead to the Path
      Computation service results also being incorrect, even if the DNS
      process was secured.</t>
    </section>

    <section title="Acknowledges">
      <t>The author would like to thank Claire Bi,Ning Kong, Liang Xia,
      Stephane Bortzmeyer,Yi Yang, Ted Lemon and Adrian Farrel for their
      review and comments that help improvement to this document.</t>
    </section>
  </middle>

  <back>
    <references title="Normative References">
      <reference anchor="RFC2119">
        <front>
          <title abbrev="RFC Key Words">Key words for use in RFCs to Indicate
          Requirement Levels</title>

          <author fullname="Scott Bradner" initials="S." surname="Bradner">
            <organization>Harvard University</organization>

            <address>
              <postal>
                <street>1350 Mass. Ave.</street>

                <street>Cambridge</street>

                <street>MA 02138</street>
              </postal>

              <phone>- +1 617 495 3864</phone>

              <email>sob@harvard.edu</email>
            </address>
          </author>

          <date month="March" year="1997" />

          <area>General</area>

          <keyword>keyword</keyword>

          <abstract>
            <t>In many standards track documents several words are used to
            signify the requirements in the specification. These words are
            often capitalized. This document defines these words as they
            should be interpreted in IETF documents. Authors who follow these
            guidelines should incorporate this phrase near the beginning of
            their document: <list>
                <t>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.</t>
              </list></t>

            <t>Note that the force of these words is modified by the
            requirement level of the document in which they are used.</t>
          </abstract>
        </front>
      </reference>

      <reference anchor="RFC2782">
        <front>
          <title>A DNS RR for specifying the location of services (DNS
          SRV)</title>

          <author fullname="A.Gulbrandsen" initials="A." surname="Gulbrandsen">
            <organization></organization>
          </author>

          <date month="February" year="2000" />
        </front>

        <seriesInfo name="RFC" value="2782" />

        <format target="http://www.rfc-editor.org/rfc/rfc2782.txt" type="TXT" />
      </reference>

      <reference anchor="RFC3397">
        <front>
          <title>Dynamic Host Configuration Protocol (DHCP) Domain Search
          Option</title>

          <author fullname="B.Aboba" initials="B." surname="Aboba">
            <organization></organization>
          </author>

          <date month="November" year="2002" />
        </front>

        <seriesInfo name="RFC" value="3397" />

        <format target="http://www.rfc-editor.org/rfc/rfc3397.txt" type="TXT" />
      </reference>

      <reference anchor="RFC3403">
        <front>
          <title>Dynamic Delegation Discovery System (DDDS) Part Three: The
          Domain Name System (DNS) Database</title>

          <author fullname="M.Mealling" initials="M." surname="Mealling">
            <organization></organization>
          </author>

          <date month="October" year="2002" />
        </front>

        <seriesInfo name="RFC" value="3403" />

        <format target="http://www.rfc-editor.org/rfc/rfc3403.txt" type="TXT" />
      </reference>

      <reference anchor="RFC3646">
        <front>
          <title>DNS Configuration options for Dynamic Host Configuration
          Protocol for IPv6 (DHCPv6)</title>

          <author fullname="R.Droms" initials="R." surname="Droms">
            <organization></organization>
          </author>

          <date month="December" year="2003" />
        </front>

        <seriesInfo name="RFC" value="3646" />

        <format target="http://www.rfc-editor.org/rfc/rfc3646.txt" type="TXT" />
      </reference>

      <reference anchor="RFC5226">
        <front>
          <title>Guidelines for Writing an IANA Considerations Section in
          RFCs</title>

          <author fullname="T.Narten" initials="T." surname="Narten">
            <organization></organization>
          </author>

          <date month="May" year="2008" />
        </front>

        <seriesInfo name="RFC" value="5226" />

        <format target="http://www.rfc-editor.org/rfc/rfc5226.txt" type="TXT" />
      </reference>

      <reference anchor="RFC4655">
        <front>
          <title>A Path Computation Element (PCE)-Based Architecture</title>

          <author fullname="A.Farrel" initials="A." surname="Farrel">
            <organization></organization>
          </author>

          <author fullname="J.P.Vasseur" initials="J.P." surname="Vasseur">
            <organization></organization>
          </author>

          <author fullname="J.Ash" initials="J." surname="Ash">
            <organization></organization>
          </author>

          <date month="August" year="2006" />
        </front>

        <seriesInfo name="RFC" value="4655" />

        <format target="http://www.rfc-editor.org/rfc/rfc4655.txt" type="TXT" />
      </reference>

      <reference anchor="RFC4674">
        <front>
          <title>Requirements for Path Computation Element (PCE)
          Discovery</title>

          <author fullname="R.Droms" initials="R." surname="Droms">
            <organization></organization>
          </author>

          <date month="December" year="2003" />
        </front>

        <seriesInfo name="RFC" value="4674" />

        <format target="http://www.rfc-editor.org/rfc/rfc4674.txt" type="TXT" />
      </reference>

      <reference anchor="RFC6805">
        <front>
          <title>The Application of the Path Computation Element Architecture
          to the Determination of a Sequence of Domains in MPLS and
          GMPLS</title>

          <author fullname="D.King" initials="D." surname="King">
            <organization></organization>
          </author>

          <author fullname="A.Farrel " initials="A." surname="Farrel">
            <organization></organization>
          </author>

          <date month="November" year="2012" />
        </front>

        <seriesInfo name="RFC" value="6805" />

        <format target="http://www.rfc-editor.org/rfc/rfc6805.txt" type="TXT" />
      </reference>

      <reference anchor="RFC4848">
        <front>
          <title>Domain-Based Application Service Location Using URIs and the
          Dynamic Delegation Discovery Service (DDDS)</title>

          <author fullname="L. Daigle" initials="D." surname="Daigle">
            <organization></organization>
          </author>

          <date month="April" year="2007" />
        </front>

        <seriesInfo name="RFC" value="4848" />

        <format target="http://www.rfc-editor.org/rfc/rfc4848.txt" type="TXT" />
      </reference>

      <reference anchor="RFC5440">
        <front>
          <title>Path Computation Element (PCE) Communication Protocol
          (PCEP)</title>

          <author fullname="JL. Le Roux" initials="JL." surname="Le Roux">
            <organization></organization>
          </author>

          <date month="April" year="2007" />
        </front>

        <seriesInfo name="RFC" value="5440" />

        <format target="http://www.rfc-editor.org/rfc/rfc5440.txt" type="TXT" />
      </reference>

      <reference anchor="RFC6781">
        <front>
          <title>DNSSEC Operational Practices, Version 2</title>

          <author fullname="O. Kolkman" initials="O." surname="Kolkman">
            <organization></organization>
          </author>

          <author fullname="W. Mekking" initials="W." surname="Mekking">
            <organization></organization>
          </author>

          <author fullname="R.Gieben" initials="R." surname="Gieben">
            <organization></organization>
          </author>

          <date month="December" year="2012" />
        </front>

        <seriesInfo name="RFC" value="6781" />

        <format target="http://www.rfc-editor.org/rfc/rfc6781.txt" type="TXT" />
      </reference>

      <reference anchor="RFC4033">
        <front>
          <title>DNS Security Introduction and Requirements</title>

          <author fullname="R. Arends" initials="R." surname="Arends">
            <organization></organization>
          </author>

          <date month="March" year="2005" />
        </front>

        <seriesInfo name="RFC" value="4033" />

        <format target="http://www.rfc-editor.org/rfc/rfc4033.txt" type="TXT" />
      </reference>
    </references>

    <references title="Informative References">
      <reference anchor="RFC5088">
        <front>
          <title>OSPF Protocol Extensions for Path Computation Element (PCE)
          Discovery</title>

          <author fullname="JL. Le Roux" initials="JL." surname="Le Roux">
            <organization></organization>
          </author>

          <date month="January" year="2008" />
        </front>

        <seriesInfo name="RFC" value="5088" />

        <format target="http://www.rfc-editor.org/rfc/rfc5088.txt" type="TXT" />
      </reference>

      <reference anchor="RFC5089">
        <front>
          <title>IS-IS Protocol Extensions for Path Computation Element (PCE)
          Discovery</title>

          <author fullname="JL. Le Roux" initials="JL." surname="Le Roux">
            <organization></organization>
          </author>

          <date month="January" year="2008" />
        </front>

        <seriesInfo name="RFC" value="5089" />

        <format target="http://www.rfc-editor.org/rfc/rfc5089.txt" type="TXT" />
      </reference>

      <reference anchor="RFC3401">
        <front>
          <title>Dynamic Delegation Discovery System (DDDS) Part One: The
          Comprehensive DDDS</title>

          <author fullname="M.Mealling" initials="M." surname="Mealling">
            <organization></organization>
          </author>

          <date month="October" year="2002" />
        </front>

        <seriesInfo name="RFC" value="3401" />

        <format target="http://www.rfc-editor.org/rfc/rfc3401.txt" type="TXT" />
      </reference>

      <reference anchor="RFC3833">
        <front>
          <title>Threat Analysis of the Domain Name System (DNS)</title>

          <author fullname="D.Atkins" initials="D." surname="Atkins">
            <organization></organization>
          </author>

          <date month="August" year="2004" />
        </front>

        <seriesInfo name="RFC" value="3833" />

        <format target="http://www.rfc-editor.org/rfc/rfc3833.txt" type="TXT" />
      </reference>

      <reference anchor="RFC5452">
        <front>
          <title>Measures for Making DNS More Resilient against Forged
          Answers</title>

          <author fullname="A.Hubert" initials="A." surname="Hubert">
            <organization></organization>
          </author>

          <date month="January" year="2009" />
        </front>

        <seriesInfo name="RFC" value="5452" />

        <format target="http://www.rfc-editor.org/rfc/rfc5452.txt" type="TXT" />
      </reference>

      <reference anchor="RFC5382">
        <front>
          <title>NAT Behavioral Requirements for TCP</title>

          <author fullname="S.Guha" initials="S." surname="Guha">
            <organization></organization>
          </author>

          <date month="October" year="2008" />
        </front>

        <seriesInfo name="RFC" value="5382" />

        <format target="http://www.rfc-editor.org/rfc/rfc5382.txt" type="TXT" />
      </reference>

      <reference anchor="RFC5295">
        <front>
          <title>The TCP Authentication Option</title>

          <author fullname="J. Touch" initials="J." surname="Touch">
            <organization></organization>
          </author>

          <date month="June" year="2010" />
        </front>

        <seriesInfo name="RFC" value="5295" />

        <format target="http://www.rfc-editor.org/rfc/rfc5295.txt" type="TXT" />
      </reference>

      <reference anchor="RFC2385">
        <front>
          <title>Protection of BGP Sessions via the TCP MD5 Signature
          Option</title>

          <author fullname="A. Heffernan" initials="A." surname="Heffernan">
            <organization></organization>
          </author>

          <date month="August" year="1998" />
        </front>

        <seriesInfo name="RFC" value="2385" />

        <format target="http://www.rfc-editor.org/rfc/rfc2385.txt" type="TXT" />
      </reference>

      <reference anchor="ALTO">
        <front>
          <title>ALTO Server Discovery</title>

          <author fullname="S. Kiesel" initials="S." surname="Kiesel">
            <organization></organization>
          </author>

          <date month="March" year="2013" />
        </front>

        <seriesInfo name="ID" value="draft-ietf-alto-server-discovery-08" />
      </reference>

      <reference anchor="BGP-LS">
        <front>
          <title>North-Bound Distribution of Link-State and TE Information
          using BGP</title>

          <author fullname="H. Gredler" initials="H." surname="Gredler">
            <organization></organization>
          </author>

          <date month="May" year="2013" />
        </front>

        <seriesInfo name="ID" value="draft-ietf-idr-ls-distribution-03" />
      </reference>

      <reference anchor="PCE-QUESTION">
        <front>
          <title>Unanswered Questions in the Path Computation Element
          Architecture</title>

          <author fullname="A. Farrel" initials="A." surname="Farrel">
            <organization></organization>
          </author>

          <date month="July" year="2013" />
        </front>

        <seriesInfo name="ID"
                    value="http://tools.ietf.org/html/draft-ietf-pce-questions-00" />
      </reference>

      <reference anchor="RFC5245">
        <front>
          <title>Interactive Connectivity Establishment (ICE): A Protocol for
          Network Address Translator (NAT) Traversal for Offer/Answer
          Protocols</title>

          <author fullname="J. Rosenberg" initials="J." surname="Rosenberg">
            <organization></organization>
          </author>

          <date month="April" year="2010" />
        </front>

        <seriesInfo name="RFC" value="5245" />

        <format target="http://www.rfc-editor.org/rfc/rfc5245.txt" type="TXT" />
      </reference>
    </references>
  </back>
</rfc>

PAFTECH AB 2003-20262026-04-23 20:46:58