Re: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile

"Templin (US), Fred L" <Fred.L.Templin@boeing.com> Thu, 05 September 2019 18:57 UTC

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From: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
To: Bob Hinden <bob.hinden@gmail.com>, "int-area@ietf.org" <int-area@ietf.org>
CC: IESG <iesg@ietf.org>, Joel Halpern <joel.halpern@ericsson.com>, "draft-ietf-intarea-frag-fragile@ietf.org" <draft-ietf-intarea-frag-fragile@ietf.org>, Suresh Krishnan <suresh@kaloom.com>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
Thread-Topic: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile
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Date: Thu, 5 Sep 2019 18:57:19 +0000
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Archived-At: <https://mailarchive.ietf.org/arch/msg/int-area/cVTMYaA5dnFgFoo-1cEC1Y17l1A>
Subject: Re: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile
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Bob,

Your effort is appreciated, but IMHO does not quite go far enough. Here is
a proposed edit:

OLD:
   Protocols and applications that rely on IP
   fragmentation will work less reliably on the Internet unless they
   also include mechanisms to detect that IP fragmentation isn't working
   reliably.

NEW:
   Protocols and applications that rely on IP
   fragmentation will work less reliably on the Internet unless they
   also include mechanisms to detect that IP fragmentation isn't working
   reliably, or encapsulate their fragments in protocol headers that can
   traverse fragment-dropping middleboxes.

Thanks - Fred

> -----Original Message-----
> From: Int-area [mailto:int-area-bounces@ietf.org] On Behalf Of Bob Hinden
> Sent: Thursday, September 05, 2019 11:29 AM
> To: int-area@ietf.org
> Cc: IESG <iesg@ietf.org>rg>; Joel Halpern <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; Suresh Krishnan
> <suresh@kaloom.com>om>; intarea-chairs@ietf.org
> Subject: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile
> 
> Hi,
> 
> Based on the discussion, I would like to propose to see if this will resolve the issues raised.   It attempts to cover the issues raised.
> 
> The full section 6.1 is included below, but only the last sentence in the second paragraph changed.
> 
> Please review and comment.
> 
> Thanks,
> Bob
> 
> 
> 
> 6.1.  For Application and Protocol Developers
> 
>    Developers SHOULD NOT develop new protocols or applications that rely
>    on IP fragmentation.  When a new protocol or application is deployed
>    in an environment that does not fully support IP fragmentation, it
>    SHOULD operate correctly, either in its default configuration or in a
>    specified alternative configuration.
> 
>    While there may be controlled environments where IP fragmentation
>    works reliably, this is a deployment issue and can not be known to
>    someone developing a new protocol or application.  It is not
>    recommended that new protocols or applications be developed that rely
>    on IP fragmentation.  Protocols and applications that rely on IP
>    fragmentation will work less reliably on the Internet unless they
>    also include mechanisms to detect that IP fragmentation isn't working
>    reliably.
> 
>    Legacy protocols that depend upon IP fragmentation SHOULD be updated
>    to break that dependency.  However, in some cases, there may be no
>    viable alternative to IP fragmentation (e.g., IPSEC tunnel mode, IP-
>    in-IP encapsulation).  In these cases, the protocol will continue to
>    rely on IP fragmentation but should only be used in environments
>    where IP fragmentation is known to be supported.
> 
>    Protocols may be able to avoid IP fragmentation by using a
>    sufficiently small MTU (e.g.  The protocol minimum link MTU),
>    disabling IP fragmentation, and ensuring that the transport protocol
>    in use adapts its segment size to the MTU.  Other protocols may
>    deploy a sufficiently reliable PMTU discovery mechanism
>    (e.g.,PLMPTUD).
> 
>    UDP applications SHOULD abide by the recommendations stated in
>    Section 3.2 of [RFC8085].