netdev - Re: [PATCH net-next v5 2/6] ipv6: ioam: Data plane support for Pre-allocated Trace

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Message-ID: <439468627.25014964.1626977189905.JavaMail.zimbra@uliege.be>
Date:   Thu, 22 Jul 2021 20:06:29 +0200 (CEST)
From:   Justin Iurman <justin.iurman@...ege.be>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org, tom@...bertland.com
Subject: Re: [PATCH net-next v5 2/6] ipv6: ioam: Data plane support for
 Pre-allocated Trace

>> diff --git a/include/uapi/linux/in6.h b/include/uapi/linux/in6.h
>> index 5ad396a57eb3..c4c53a9ab959 100644
>> --- a/include/uapi/linux/in6.h
>> +++ b/include/uapi/linux/in6.h
>> @@ -145,6 +145,7 @@ struct in6_flowlabel_req {
>>  #define IPV6_TLV_PADN		1
>>  #define IPV6_TLV_ROUTERALERT	5
>>  #define IPV6_TLV_CALIPSO	7	/* RFC 5570 */
>> +#define IPV6_TLV_IOAM		49	/* TEMPORARY IANA allocation for IOAM */
> 
> why temporary and what is the risk the value changes between now and the
> final version?

David,

On the "why": it was initially requested by Tom Herbert to clarify that it was not standardized yet (at that time). And this is also the mention ("temporary") next to the allocated code by IANA (see [1]). So it's more about semantic here, nothing that important.

On the risk of change: short answer, there is none. Long answer, once the code is (temporarily) allocated, either the draft make it through and the current code allocation is kept by removing the "temporary" mention, or it is considered as deprecated and removed. Note that extension requests are possible (already made it once). Again, there are two related drafts: draft-ietf-ippm-ioam-data [2] is about to be standardized (see the current process status [3]), while draft-ietf-ippm-ioam-ipv6-options [4] (where the IANA code we're talking about is defined) will follow the same path shortly.

  [1] https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-2
  [2] https://datatracker.ietf.org/doc/html/draft-ietf-ippm-ioam-data
  [3] https://datatracker.ietf.org/doc/search/?name=draft-ietf-ippm-ioam-data&activedrafts=on&rfcs=on
  [4] https://datatracker.ietf.org/doc/html/draft-ietf-ippm-ioam-ipv6-options