Re: [OPSAWG] [IANA #1240167] IANA question regarding draft-ietf-opsawg-ipfix-srv6-srh-01

[Benoit Claise <[e-mail]>]

Hi Amanda, IPFIX IE doctors,

See inline.

On 9/30/2022 4:58 AM, Amanda Baber via RT wrote:
> Hi Benoit, all,
>
>> Dear IPFIX doctors, (IANA),
>>
>> We would like to get your feedback regarding the IANA section in
>> draft-ietf-opsawg-ipfix-srv6-srh-01.
>> Especially, the two following information elements:
>> srhFlagsIPv6:
>> https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6-
>> srh-01#section-5.1
>> srhSegmentEndpointBehavior:
>> https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6-
>> srh-01#section-5.11
> We can keep separate registries in sync (although we don't currently have automation to ensure this), but is the intention for the IPFIX IPv6 SRH Flags and IPFIX SRV6 Endpoint Behavior registries to be contained within each IPFIX IE registration's Description field?
>
> In 2020, with IE Doctor approval, all IPFIX IE Description field tables that constituted sub-registries were replaced with links to separate sub-registries located outside of the IPFIX Information Elements registry. You can see the list of sub-registries under the heading "Registries included below":
>
> https://www.iana.org/assignments/ipfix
>   
>> I went to the IANA table in Philly and we discussed those. Hence I
>> copied IANA here.
>> In the currentdraft-ietf-opsawg-ipfix-srv6-srh-01
>> <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6- 
>> srh-01>
>> version, we created two IPFIX subregistries, which mimic existing
>> Segment Routing registries.
>> The main reason is that we are in favor of having a self contained
>> IPFIX
>> IANA registry, which we can download as a cron job in the collector.
>> We
>> discussed such a project with Michelle Cotton in the past (I know that
>> Michelle moved on).
> I'm afraid we don't have any of Michelle's notes on this topic. What will you need IANA to do? We may need to put you in touch with IANA's technical director. In the future, the registries will be moved from an XML-based to a database-based registry system.
Regarding the argument of "having a self having a self contained IPFIX 
IANA registry, which we can download as a cron job in the collector", 
what we need is the ability to retrieve either the entire registry in 
one go, or have pointers to other (registries) the IPFIX collector has 
to take into account ... in an automatic manner
The former, with subregistries duplication (and synchronization) might 
be beyond repair at this point in time (at least, I don't have the 
courage to engage), on top of pushing much administration to IANA for 
the synchronization/maintenance

Looking closer at the IFPIX registry, let me provide a logic that might 
work, without too much changes IMO.

Let's say I take care of a IPFIX collector, which I need to update on 
regular basis, there are different cases:
1. A new IPFIX IE is added in the registry
     Ex: Let's say I specify in IANA the IPFIX IE 492 = "my-new-field"
     I download the entire registry as a cronjob, install it in my 
collector, and I can now understand all flow records that contain the 
new IPFIX IE 492
2. A new value is added for one of the IPFIX sub-registries
     Ex: Let's say I add value 25 = "my-new-classification-engine-id" at 
https://www.iana.org/assignments/ipfix/ipfix.xhtml#classification-engine-ids
     What is the logic?
     I download the entire registry as a cronjob, parse the file, when I 
arrive at IPFIX field 101 (classificationEngineId) => I do a lookup on 
*[https://www.iana.org/assignments/ipfix/ipfix.xhtml#classification-engine-ids] 
in the Description field* , read the new value 25, install it in my 
collector, and I can now understand all flow records that contain a 
classificationEngineId value 25.
3. A new value is added for in the external (non-IPFIX) registry
     Ex: a new port is added to 
https://www.iana.org/assignments/service-names-port-numbers].
     The following IPFIX IEs refer to this registry: 
sourceTransportPort, destinationTransportPort, udpSourcePort, 
udpDestinationPort, udpDestinationPort, etc.
     What is the logic?
     I download the entire registry as a cronjob, parse the file, when I 
arrive at any of those IPFIX IEs => I do a lookup**on 
https://www.iana.org/assignments/service-names-port-numbers*in the 
Addition Information field*, read the new port value, install it in my 
collector, and I can now understand all flow records that contain the 
new port value

At least the logic could work (even if looking up two fields is not 
ideal from a logic point of view)
I checked all http links in the IPFIX registry and found 3 "exceptions"
- [http://standards.ieee.org/regauth/ethertype/eth.txt], will not work, 
but we might consider this one as an exception.
- portRangeStart and portRangeEnd point to 
https://www.iana.org/assignments/service-names-port-numbers. Not to sure 
how to treat this one in an automatic way
- [https://www.iana.org/assignments/ianaiftype-mib] should be treated 
differently, but that's fine.

One conclusion is that there are different treatments whether the links 
are in the *Description field* or the *Additional Information* field.
Interestingly, RFC 7102 doesn't mention this *Additional Information* 
field :-) And this is precisely this one that I would like to use below, 
since we speak about non-IPFIX registries in 
draft-ietf-opsawg-ipfix-srv6-srh.
If we don't pay attention to that detail, here is a proposal (combining 
Med proposal with the logic above)

5.1
<https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6- 
srh-01#section-5.1>.
srhFlagsIPv6

Name:  srhFlagsIPv6

ElementID:  TBD1

Description:  This IE identifies the 8-bit flags defined in the SRH.
       Assigned flags and their meanings are provided in the "Segment
Routing Header Flags" registry.

Abstract Data Type:  unsigned8

Data Type Semantics:  flags

Reference:  [RFC-to-be],RFC8754
<https://datatracker.ietf.org/doc/html/rfc8754>

*Additional reference: ****https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#segment-routing-header-flags*


Note: and similarly for5.9 
<https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6-srh-01#section-5.9>. 
srhActiveSegmentIPv6Type Note: as you can see, I have a different opinion that Med on this one => we need to point to the specific registry within the group, for automatic treatment

Would that work, or IANA/IPFIX doctors will frown upon because the*"additional information"*  field is not mentioned in RFC7102?

Regards, Benoit

>
>> On top of that, it might be beneficial for the
>> IPFIX
>> experts to review any changes coming from a registry we mimic, just to
>> see if there are no new inconsistencies from an IPFIX point of view.
>>
>> However, Med, in cc., has a valid point that the current IPFIX IANA
>> entries are inconsistencies already.
>> Ex: destinationTransportPort points to a different registry
>> Ex: tcpControlBit. See
>> https://datatracker.ietf.org/doc/draft-boucadair-opsawg-rfc7125-
>> update/
>> So he advocated that we don't duplicate, with an IPFIX subregistry,
>> information stemming from a different source. Pointing to the existing
>> registry (ex: "Segment Routing Header Flags") + a RFC reference is
>> sufficient for him. Solving the self-contained IPFIX registry issue
>> would be a (too) huge job at this point in time.
>>
>> This is what we currently have in the draft:
>>
>> 5.1
>> <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6- 
>> srh-01#section-5.1>.
>> srhFlagsIPv6
>>
>> Name:  srhFlagsIPv6
>>
>> ElementID:  TBD1
>>
>> Description:  This Information Element identifies the 8-bit flags
>>     defined in the SRH.  Values for this Information Element are
>>     listed in the "IPFIX IPv6 SRH Flags" registry, see [IANA-IPFIX
>> <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6- 
>> srh-01#ref-IANA-IPFIX>].
>>     srhFlagsIPv6 values must not be directly added to this "IPFIX IPv6
>>     SRH Flags" registry.  They must instead be added to the "Segment
>>     Routing Header Flags" registry.  Both the "IPFIX IPv6 SRH Flags"
>>     and the "Segment Routing Header Flags" registries must be kept in
>>     synch.  Initial values in the registry are defined by the table
>>     below.
>>
>> +--------+-------------------+--------------------------------------+
>> | Value  |    Description    |              Reference               |
>> +--------+-------------------+--------------------------------------+
>> | 0-1    | Unassigned        |                                      |
>> +--------+-------------------+--------------------------------------+
>> | 2      | O-flag            |  [RFC-ietf-6man-spring-srv6-oam-13]  |
>> +--------+-------------------+--------------------------------------+
>> | 3-7    | Unassigned        |                                      |
>> +--------+-------------------+--------------------------------------+
>>
>> Table 2: "IPFIX IPv6 SRH Flags" registry
>>
>>
>> Note to IANA:  Add a note to the "IPFIX SRV6 Endpoint Behavior"
>>     registry so that new values are echoed in the new "IPFIX SRv6
>>     EndPoint Behavior
>>
>> Abstract Data Type:  unsigned8
>>
>> Data Type Semantics:  flags
>>
>> Reference:  [RFC-to-be],RFC8754
>> <https://datatracker.ietf.org/doc/html/rfc8754>
>>
>> This is what Med proposes:
>>
>> 5.1
>> <https://datatracker.ietf.org/doc/html/draft-ietf-opsawg-ipfix-srv6- 
>> srh-01#section-5.1>.
>> srhFlagsIPv6
>>
>> Name:  srhFlagsIPv6
>>
>> ElementID:  TBD1
>>
>> Description:  This IE identifies the 8-bit flags defined in the SRH.
>>        Assigned flags and their meanings are provided in the "Segment
>> Routing
>>        Header Flags" registry.
>>
>> Abstract Data Type:  unsigned8
>>
>> Data Type Semantics:  flags
>>
>> Reference:  [RFC-to-be],RFC8754
>> <https://datatracker.ietf.org/doc/html/rfc8754>
> When IANA links to this registry, will the link have to point to, e.g.,https://www.iana.org/assignments/segment-routing/segment-routing#the-specific-registry, or would it be sufficient to point tohttps://www.iana.org/assignments/segment-routing  (the registry group, rather than the specific registry within it)?
>
>> We basically agree that a registry lookup is required for the IPFIX
>> Collector.
>> An IPFIX Exporter will export what he sees, regardless of the semantic
>> or an IANA registry. The IPFIX Collector will report a potential
>> problem
>> if the observed value is not in the IANA registry (bug, IANA entry
>> hijacked, another convention => if value not observed, I'll send an
>> error code instead, etc)
>>
>> Bottom line: we have two different ways to model the srhFlagsIPv6 and
>> srhSegmentEndpointBehavior in IANA, with or without an IPFIX
>> subregistry.
>> Can you share your views on the best way to register those IEs.
>>
>> Thanks and regards, Benoit
> thanks,
>
> Amanda Baber
> IANA Operations Manager
>
>