RE: New draft: "IPv6 Source Fragmentation for Link Adaptation Avoidance"

["Templin, Fred L" <[e-mail]>]

Hi Dan,

> The engineering effort to improve this situation is closely tied
> to how severe the problem really is, and how often we hit the
> small MTU layer 2 links (that draft-generic-6man-tunfrag is
> trying to fix) and how often we hit IPv6/IPv4 translators (that
> the last paragraph of Section 5 of RFC2460 is trying to fix, but
> doesn't quite handle well with stateless IPv6/IPv4 translators).
> 
> Myself, I am frustrated with layer 2 networks that have smaller
> than 1500 byte MTUs, because we know anything that looks like
> Ethernet succeeds (even if it isn't Ethernet, e.g., WiFi), and
> technologies that don't look like Ethernet have enjoyed less
> success.  Can we expect those networks to fail in the market,
> or to look enough like Ethernet that IP works well on top of
> them, making draft-generic-6man-tunfrag unnecessary?  There
> is a similar question for IPv6/IPv4 translators -- will they
> persist long enough to make the engineering effort to improve
> that last paragraph in Section 5 of RFC2460 worth while, and
> will we see deployment in IPv6 hosts while there are still
> IPv6/IPv4 translators?

About this, one thing I think we can agree on is that the
value 1280 is in no way significant to IPv4 nodes. So, the
final paragraph in Section 5 of RFC2460 might just as well
be adjusted to say that the node is not required to reduce
the size of its subsequent packets to less than 1500 bytes
(not 1280).

Thanks - Fred