Earlier, Fernando Gont wrote, in part: > ... my question was about whether the "atomic fragments" > that were found in the wild were the result of translators, > or of IPv6 networks that "violate" the standard and > do not support an MTU of >= 1280.
I have been told of real-world IPv6 deployments where the link MTU is smaller than 1280, while the limited link bandwidth makes adding a new segmentation protocol layer impractical. I believe these account for some of the 576 byte or 512 byte advertised Link MTU sizes in IPv6 PMTU "Too Big" messages that are seen in the real world. I also know of real-world IPv6 deployments with translators. I expect translators to become much more common soon. As far as I am aware, neither of the above would produce PMTU "Too Big" messages with an advertised link MTU very much under 500 bytes. IMHO, the 1280 byte number is far too big for a minimum IPv6 MTU. I've held the view that much above 512 bytes is problematic on RF links for MANY years now, as the Minutes from long ago illustrate (search for "MTU"): <ftp://ftp.ietf.org/ietf-online-proceedings/94dec/area.and.wg.reports/ipng/ipngwg/ipngwg-minutes-94dec.txt> <ftp://ftp.ietf.org/ietf-online-proceedings/94jul/area.and.wg.reports/ipng/sipp/sipp-minutes-94jul.txt> Ran -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
