Re: [IPFIX] RFC 6728 IETF IPFIX Yang Discussion

Gerhard Muenz <[email protected]> Sat, 13 Jan 2018 10:43:32 +0100
Newsgroups gmane.ietf.ipfix
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Marta, all,

A few additional thoughts regarding your questions:

1) I would not expect that not following current naming convention 
hinders implementation of RFC 6728. On the other hand, if we change just 
the names of the identifiers, we lose interoperability with older 
implementations that may exist.

2) I think that it is reasonable that destinationIPAddress is mandatory 
because network management systems should be able to query the IP 
address to which an Exporting Process sends data. As Paul stated, RFC 
6728 does not say how the destination IP address is set.

3) SCTP is still a mandatory transport for a compliant implementation of 
an IPFIX device, not a feature. See: 
https://tools.ietf.org/html/rfc7011#section-10.1

Best regards,
Gerhard



On 10.01.2018 08:33, Benoit Claise wrote:
> Hi,
>>
>> Marta, Benoit,
>>
>>
>> 1. Are there efforts to update other RFCs to meet the latest YANG 
>> best practices?
>>
> Yes. Ex: https://datatracker.ietf.org/doc/draft-ietf-netmod-rfc7223bis/
> The goal is to specify NMDA-compliant 
> (draft-ietf-netmod-revised-datastores-09 
> <https://datatracker.ietf.org/doc/draft-ietf-netmod-revised-datastores/>) 
> YANG modules
>>
>>
>> 2. Since the IPFIX WG closed, there has been little ongoing IPFIX 
>> work in the IETF. Is there a specific need to update RFC 6728 rather 
>> than just recognising it as a product of it's time?
>>
> This type of feedback should come from implementation experience.
>
> Regards, Benoit
>>
>> Note that it's > 5 years old.
>>
>>
>> Also see @PJ inline:
>>
>>
>> On 09/01/2018 16:01, Benoit Claise wrote:
>>
>>     Hi Marta,
>>
>>         Hello,
>>
>>         I am reaching out to the IETF IPFIX mailing list  on some
>>         issues I have run into with respect to RFC 6728
>>         “Configuration Data Model for the IP Flow Information Export
>>         (IPFIX)  and Packet Sampling (PSAMP) Protocols”
>>
>>          1. RFC 6728 doesn’t meet the latest Yang Best Practices
>>             (https://tools.ietf.org/html/draft-ietf-netmod-rfc6087bis-15#section-4.3.1
>>             <https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_html_draft-2Dietf-2Dnetmod-2Drfc6087bis-2D15-23section-2D4.3.1&d=DwMD-g&c=LFYZ-o9_HUMeMTSQicvjIg&r=f8F8yzrqBTw6EPtR1rbibO_VFIc-cdnjIJ9he_qu7xs&m=0c5ATjuT0-4IlDzLYM9h_RbPjCBQUv_6aExRL_fl-5M&s=Hhi7V6njCFNBbSsjC6sPgNfVu5DA8iQzdzsnA_iQBzQ&e=>).
>>             Leaf identifiers are camel case (e.g., destinationAddress
>>             instead of destination-address). Are there any ongoing
>>             efforts to update RFC 6728 to meet the latest best practices?
>>
>>     Not as far as I know.
>>
>>     Regards, Benoit
>>
>>         2.
>>
>>            Identifiers SHOULD follow a consistent naming pattern
>>         throughout the
>>
>>            module.  Only lower-case letters, numbers, and dashes
>>         SHOULD be used
>>
>>            in identifier names.  Upper-case characters and the underscore
>>
>>            character MAY be used if the identifier represents a
>>         well-known value
>>
>>            that uses these characters.
>>
>>            Identifiers SHOULD include complete words and/or
>>         well-known acronyms
>>
>>            or abbreviations. Child nodes within a container or list
>>         SHOULD NOT
>>
>>            replicate the parent identifier.  YANG identifiers are
>>         hierarchical
>>
>>            and are only meant to be unique within the the set of
>>         sibling nodes
>>
>>            defined in the same module namespace.
>>
>>            It is permissible to use common identifiers such as "name"
>>         or "id" in
>>
>>            data definition statements, especially if these data nodes
>>         share a
>>
>>            common data type.
>>
>>            Identifiers SHOULD NOT carry any special semantics that
>>         identify data
>>
>>            modelling properties.  Only YANG statements and YANG extension
>>
>>            statements are designed to convey machine readable data
>>         modelling
>>
>>            properties.  For example, naming an object "config" or
>>         "state" does
>>
>>            not change whether it is configuration data or state
>>         data.  Only
>>
>>            defined YANG statements or YANG extension statements can
>>         be used to
>>
>>            assign semantics in a machine readable format in YANG.
>>
>>          3. I generated the RFC 6728 yang tree (see attached). The
>>             tcp and udp exporting processes support a
>>             destinationIPAddress (line 400, 455) which is mandatory. 
>>             The type is inet:ip-address.
>>
>>              1. A collector may be doing load balancing.  Rather than
>>                 managing ip-addresses, the collector may be using DNS
>>                 (an exporter could resolve from the domain name where
>>                 the collector is located).
>>
>>
>> @PJ: Load balancing and DNS are independent. Load balancing IPFIX is 
>> probably a bad idea since templates need to be available on all 
>> collectors, and out of step sequence numbers in the data records 
>> would cause spurious reports of lost data. If DNS is used to obtain 
>> the collector's address, arguably it should be a one-time lookup 
>> rather than incurring a DNS lookup per export packet.
>>
>>
>>         4.
>>
>>             1.
>>              2. The collector address may be learnt via other methods
>>                 (e.g., through DHCP options)
>>              3. A choice statement to select what method to use seems
>>                 more appropriate than what is presently in RFC 6728. 
>>                 For example (use some shorthand)
>>
>>         choice destination-method{
>>
>>         case destination-address{
>>
>>         leaf destination-address// rw with type inet:host
>>
>>         }
>>
>>         case dhcp-acquired-address{
>>
>>         container dcp-acquired-address{
>>
>>         leaf destination-ip-address inet-address //ro
>>
>>         }
>>
>>         }
>>
>>         However I can’t augment to ietf-ipfix because
>>         destinationIPAddress is mandatory.  Can the group suggest
>>         methods to (a) change the destinationIPAddress type and (b)
>>         allow a choice?
>>
>>
>> @PJ: The selection could also be done out of band so the exporter 
>> need not know how the address is determined. eg a configuration 
>> system could determine the address by any of these methods or 
>> otherwise, and impose that address using the current model.
>>
>>          5. RFC 6728 mandates SCTP transport.  I understand the logic
>>             behind this (IETF prefers use of SCTP).  There are
>>             situations where sctp is unnecessary and not supported
>>             (e.g., point to point connection).  During netconf
>>             negotiations you can announce your feature set (currently
>>             sctptransport is not a feature).  Is there ongoing work
>>             in updating RFC 6728 to include sctptransport as a
>>             feature (so that the device can announce whether or not
>>             it supports sctptransport)?
>>
>>
>> @PJ Same answer as point (2) above, ie is this necessary and useful?
>>
>> P.
>>
>
>
>
> _______________________________________________
> IPFIX mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/ipfix


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    <br>
    Marta, all,<br>
    <br>
    A few additional thoughts regarding your questions:<br>
    <br>
    1) I would not expect that not following current naming convention
    hinders implementation of RFC 6728. On the other hand, if we change
    just the names of the identifiers, we lose interoperability with
    older implementations that may exist.<br>
    <br>
    2) I think that it is reasonable that destinationIPAddress is
    mandatory because network management systems should be able to query
    the IP address to which an Exporting Process sends data. As Paul
    stated, RFC 6728 does not say how the destination IP address is set.<br>
    <br>
    3) SCTP is still a mandatory transport for a compliant
    implementation of an IPFIX device, not a feature. See:
    <a class="moz-txt-link-freetext" href="https://tools.ietf.org/html/rfc7011#section-10.1">https://tools.ietf.org/html/rfc7011#section-10.1</a><br>
    <br>
    Best regards,<br>
    Gerhard<br>
    <br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 10.01.2018 08:33, Benoit Claise
      wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:[email protected]">
      <meta http-equiv="Content-Type" content="text/html;
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      <div class="moz-cite-prefix">Hi,<br>
      </div>
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        <div class="WordSection1">
          <p class="MsoNormal">Marta, Benoit,<o:p></o:p></p>
          <div>
            <div>
              <p class="MsoNormal"><br>
                1. Are there efforts to update other RFCs to meet the
                latest YANG best practices?<br>
              </p>
            </div>
          </div>
        </div>
      </blockquote>
      Yes. Ex: <a class="moz-txt-link-freetext"
        href="https://datatracker.ietf.org/doc/draft-ietf-netmod-rfc7223bis/"
        moz-do-not-send="true">https://datatracker.ietf.org/doc/draft-ietf-netmod-rfc7223bis/</a><br>
      The goal is to specify NMDA-compliant (<a
href="https://datatracker.ietf.org/doc/draft-ietf-netmod-revised-datastores/"
        moz-do-not-send="true">draft-ietf-netmod-revised-datastores-09</a>)
      YANG modules<br>
      <blockquote type="cite"
cite="mid:[email protected]">
        <div class="WordSection1">
          <div>
            <div>
              <p class="MsoNormal"> <br>
                2. Since the IPFIX WG closed, there has been little
                ongoing IPFIX work in the IETF. Is there a specific need
                to update RFC 6728 rather than just recognising it as a
                product of it's time? </p>
            </div>
          </div>
        </div>
      </blockquote>
      This type of feedback should come from implementation experience.<br>
      <br>
      Regards, Benoit<br>
      <blockquote type="cite"
cite="mid:[email protected]">
        <div class="WordSection1">
          <div>
            <div>
              <p class="MsoNormal">Note that it's &gt; 5 years old.<o:p></o:p></p>
              <p class="MsoNormal"><br>
                Also see @PJ inline:<br>
                <br>
                <br>
                On 09/01/2018 16:01, Benoit Claise wrote:<o:p></o:p></p>
            </div>
            <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
              <div>
                <p class="MsoNormal">Hi Marta,<o:p></o:p></p>
              </div>
              <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
                <p class="MsoNormal">Hello,<o:p></o:p></p>
                <p class="MsoNormal">I am reaching out to the IETF IPFIX
                  mailing list  on some issues I have run into with
                  respect to RFC 6728 “Configuration Data Model for the
                  IP Flow Information Export (IPFIX)  and Packet
                  Sampling (PSAMP) Protocols”<o:p></o:p></p>
                <p class="MsoNormal"> <o:p></o:p></p>
                <ol style="margin-top:0cm" start="1" type="1">
                  <li class="MsoNormal"
                    style="margin-left:0cm;mso-list:l1 level1 lfo3">RFC
                    6728 doesn’t meet the latest Yang Best Practices (<a
href="https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_html_draft-2Dietf-2Dnetmod-2Drfc6087bis-2D15-23section-2D4.3.1&amp;d=DwMD-g&amp;c=LFYZ-o9_HUMeMTSQicvjIg&amp;r=f8F8yzrqBTw6EPtR1rbibO_VFIc-cdnjIJ9he_qu7xs&amp;m=0c5ATjuT0-4IlDzLYM9h_RbPjCBQUv_6aExRL_fl-5M&amp;s=Hhi7V6njCFNBbSsjC6sPgNfVu5DA8iQzdzsnA_iQBzQ&amp;e="
                      moz-do-not-send="true">https://tools.ietf.org/html/draft-ietf-netmod-rfc6087bis-15#section-4.3.1</a>).  
                    Leaf identifiers are camel case (e.g.,
                    destinationAddress instead of destination-address). 
                    Are there any ongoing efforts to update RFC 6728 to
                    meet the latest best practices?<o:p></o:p></li>
                </ol>
              </blockquote>
              <p class="MsoNormal">Not as far as I know.<br>
                <br>
                Regards, Benoit<br>
                <br>
                <o:p></o:p></p>
              <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
                <ol style="margin-top:0cm" start="2" type="1">
                  <li class="MsoNormal"
                    style="margin-left:0cm;mso-list:l1 level1 lfo3"><o:p> </o:p></li>
                </ol>
                <p class="MsoNormal" style="margin-left:36.0pt"> <o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   Identifiers SHOULD
                    follow a consistent naming pattern throughout the</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   module.  Only
                    lower-case letters, numbers, and dashes SHOULD be
                    used</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   in identifier
                    names.  Upper-case characters and the underscore</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   character MAY be
                    used if the identifier represents a well-known value</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   that uses these
                    characters.</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif"> </span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   Identifiers SHOULD
                    include complete words and/or well-known acronyms</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   or abbreviations. 
                    Child nodes within a container or list SHOULD NOT</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   replicate the
                    parent identifier.  YANG identifiers are
                    hierarchical</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   and are only meant
                    to be unique within the the set of sibling nodes</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   defined in the same
                    module namespace.</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif"> </span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   It is permissible
                    to use common identifiers such as "name" or "id" in</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   data definition
                    statements, especially if these data nodes share a</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   common data type.</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif"> </span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   Identifiers SHOULD
                    NOT carry any special semantics that identify data</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   modelling
                    properties.  Only YANG statements and YANG extension</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   statements are
                    designed to convey machine readable data modelling</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   properties.  For
                    example, naming an object "config" or "state" does</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   not change whether
                    it is configuration data or state data.  Only</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   defined YANG
                    statements or YANG extension statements can be used
                    to</span><o:p></o:p></p>
                <p class="MsoNormal"><span
                    style="font-size:10.0pt;font-family:&quot;Courier
                    New ;color:black&quot;,serif">   assign semantics in
                    a machine readable format in YANG.</span><o:p></o:p></p>
                <p class="MsoNormal"> <o:p></o:p></p>
                <ol style="margin-top:0cm" start="3" type="1">
                  <li class="MsoNormal"
                    style="margin-left:0cm;mso-list:l1 level1 lfo3">I
                    generated the RFC 6728 yang tree (see attached). 
                    The tcp and udp exporting processes support a
                    destinationIPAddress (line 400, 455) which is
                    mandatory.  The type is inet:ip-address.  <o:p></o:p></li>
                </ol>
                <ol style="margin-top:0cm" start="3" type="1">
                  <ol style="margin-top:0cm" start="1" type="a">
                    <li class="MsoNormal"
                      style="margin-left:0cm;mso-list:l1 level2 lfo3">A
                      collector may be doing load balancing.  Rather
                      than managing ip-addresses, the collector may be
                      using DNS (an exporter could resolve from the
                      domain name where the collector is located).  <o:p></o:p></li>
                  </ol>
                </ol>
              </blockquote>
            </blockquote>
            <p class="MsoNormal"><br>
              @PJ: Load balancing and DNS are independent. Load
              balancing IPFIX is probably a bad idea since templates
              need to be available on all collectors, and out of step
              sequence numbers in the data records would cause spurious
              reports of lost data. If DNS is used to obtain the
              collector's address, arguably it should be a one-time
              lookup rather than incurring a DNS lookup per export
              packet.<br>
              <br>
              <br>
              <o:p></o:p></p>
            <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
              <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
                <ol style="margin-top:0cm" start="4" type="1">
                  <li class="MsoNormal"
                    style="margin-left:0cm;mso-list:l1 level1 lfo3"><o:p> </o:p></li>
                </ol>
                <ol style="margin-top:0cm" start="4" type="1">
                  <ol style="margin-top:0cm" start="1" type="a">
                    <li class="MsoNormal"
                      style="margin-left:0cm;mso-list:l1 level2 lfo3"><o:p> </o:p></li>
                    <li class="MsoNormal"
                      style="margin-left:0cm;mso-list:l1 level2 lfo3">The
                      collector address may be learnt via other methods
                      (e.g., through DHCP options)<o:p></o:p></li>
                    <li class="MsoNormal"
                      style="margin-left:0cm;mso-list:l1 level2 lfo3">A
                      choice statement to select what method to use
                      seems more appropriate than what is presently in
                      RFC 6728.  For example (use some shorthand)<o:p></o:p></li>
                  </ol>
                </ol>
                <p class="MsoNormal" style="margin-left:72.0pt"> <o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">choice
                  destination-method{<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">               
                  case destination-address{<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">                               
                  leaf destination-address// rw with type inet:host <o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">               
                  }<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">               
                  case dhcp-acquired-address{<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">                               
                  container dcp-acquired-address{<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">                                               
                  leaf destination-ip-address inet-address //ro<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">               
                  }<o:p></o:p></p>
                <p class="MsoNormal" style="margin-left:72.0pt">}<o:p></o:p></p>
                <p class="MsoNormal">                                <o:p></o:p></p>
                <p class="MsoNormal">                               
                  However I can’t augment to ietf-ipfix because
                  destinationIPAddress is mandatory.  Can the group
                  suggest methods to (a) change the destinationIPAddress
                  type and (b) allow a choice?<o:p></o:p></p>
              </blockquote>
            </blockquote>
            <p class="MsoNormal"><br>
              @PJ: The selection could also be done out of band so the
              exporter need not know how the address is determined. eg a
              configuration system could determine the address by any of
              these methods or otherwise, and impose that address using
              the current model.<br>
              <br>
                <o:p></o:p></p>
            <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
              <blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
                <ol style="margin-top:0cm" start="5" type="1">
                  <li class="MsoNormal"
                    style="margin-left:0cm;mso-list:l1 level1 lfo3">RFC
                    6728 mandates SCTP transport.  I understand the
                    logic behind this (IETF prefers use of SCTP).  There
                    are situations where sctp is unnecessary and not
                    supported (e.g., point to point connection).  During
                    netconf negotiations you can announce your feature
                    set (currently sctptransport is not a feature).  Is
                    there ongoing work in updating RFC 6728 to include
                    sctptransport as a feature (so that the device can
                    announce whether or not it supports sctptransport)?<o:p></o:p></li>
                </ol>
              </blockquote>
            </blockquote>
            <p class="MsoNormal"><br>
              @PJ Same answer as point (2) above, ie is this necessary
              and useful?<br>
              <br>
              P.<o:p></o:p></p>
          </div>
        </div>
      </blockquote>
      <br>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <br>
      <pre wrap="">_______________________________________________
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