Re: [Int-area] Fwd: New Version Notification for draft-herbert-ipv4-udpencap-eh-00.txt

[Tom Herbert <[e-mail]>]

On Wed, Mar 6, 2019 at 9:03 AM Joe Touch <[e-mail]> wrote:
>
>
> On 3/6/2019 8:22 AM, Tom Herbert wrote:
> > On Tue, Mar 5, 2019 at 10:08 PM Joe Touch <[e-mail]> wrote:
> >> Isn't the biggest problem with IP fragmentation the inability to NAT
> >> because the transport headers are in the first fragment only (which may
> >> go via another path)?
> >>
> > Joe,
> >
> > The size of the IP identifier is mentioned as one of the problems with
> > IPv4 fragmentation in draft-ietf-intarea-frag-fragile.
>
> That could have been handled by new rules to drop incompletely
> reassembled datagrams based on measured expected reordering, rather than
> max lifetime.
>
> > The fact that
> > intermediate nodes might fragment in IPv4 and not in IPv6 is another
> > discrepancy between the protocols.
>
> Well, strictly the difference is only whether intermediate nodes violate
> IPv4 or IPv6. IPv4 with DF isn't supposed to be on-path fragmented any
> more than IPv6 is; in both cases, nodes that violate the protocols can -
> and will - do whatever they want.
>
> But there's no point in making "laws for the lawless", as I've
> repeatedly noted throughout the IETF.
>
> > The transport layer not in all
> > fragments is a problem for NAT, that might addressed by encapsulating
> > the fragmention in UDP.
>
> That is a problem for NAT and transport-based ECMP.
>
> And yes, we can build an Internet on the Internet - again, as I've noted
> repeatedly throughout the IETF. Or we can use UDP fragmentation - which
> ought to solve all these issues in one shot.
>
> So what's the gain here?

Joe,

Please view the proposal in its entirety. The stated objectives are to
support IPv6 extension headers in IPv4 and to allow encapsulate of
extension headers (both for IPv6 and Ipv4) in UDP to improve
deliverability. Fragmentation header is just one example.

Tom

>
> Joe
>