Re: [Dots] Suresh Krishnan's Discuss on draft-ietf-dots-requirements-18: (with DISCUSS and COMMENT)

["Konda, Tirumaleswar Reddy" <[e-mail]>]

Hi Suresh,

Please see inline

> -----Original Message-----
> From: Suresh Krishnan <[e-mail]>
> Sent: Thursday, February 21, 2019 7:41 PM
> To: The IESG <[e-mail]>
> Cc: [e-mail]; Liang Xia
> <[e-mail]>; [e-mail];
> [e-mail]; [e-mail]
> Subject: Suresh Krishnan's Discuss on draft-ietf-dots-requirements-18: (with
> DISCUSS and COMMENT)
> 
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> Suresh Krishnan has entered the following ballot position for
> draft-ietf-dots-requirements-18: Discuss
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> 
> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
> 
> I think SIG-002 is a bit underspecified. It points to draft-ietf-intarea-frag-fragile
> as the recommended mechanism for discovering PMTUD, but in fact draft-ietf-
> intarea-frag-fragile is designed to provide a list of potential solutions and
> recommendations for application and protocol developers (Section 7.1.). So I
> expect this document to specify what it intends to do for fragmentation instead
> of a vague reference.

Added the following line to SIG-002:

If the total message size exceeds the path MTU, the DOTS agent MUST split the message into separate messages; for example, the list of mitigation scope types 
could be split into multiple lists and each list conveyed in a new message.


> 
> IPv4 does not support a minimum PMTU of 576 as claimed here. RFC791
> clearly states that the minimum PMTU is 68 octets. I suggest rewording this to
> 
> OLD:
> DOTS implementations MAY rely on a PMTU of 576 bytes for IPv4 datagrams,
> as discussed in [RFC0791] and [RFC1122].
> 
> NEW:
> DOTS implementations MAY assume on a PMTU of 576 bytes for IPv4
> datagrams, as every IPv4 host must be capable of receiving a packet whose
> length is equal to
> 576 bytes as discussed in [RFC0791] and [RFC1122].
> 
> 
> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
> 
> The recommendation of the 1280 byte minimum for IPv6 needs some
> reasoning and a reference to RFC8200. e.g. something like this would work
> 
> OLD:
> If the PMTU cannot be discovered, DOTS agents MUST assume a PMTU of 1280
> bytes for IPv6.
> 
> NEW:
> If the PMTU cannot be discovered, DOTS agents MUST assume a PMTU of 1280
> bytes, as IPv6 requires that every link in the Internet have an MTU of 1280
> octets or greater as specified in [RFC8200].

Thanks, updated draft to use the NEW text for IPv4 and IPv6.

Cheers,
-Tiru

>