Re: Additional implementation scenario for PMTU RFC 1981

[itojun at itojun.org (Jun-ichiro itojun Hagino)]

> In PMTU RFC 1981 Most of the implementation scenarios have been considered.
> 
> This RFC suggests that the IP layer stores PMTU information, so that PMTU
> information can be shared across different packetization layer.
> 
> If IP layer discovers PMTU information due to the packet sent by one of the
> packetization layer (Assume TCP), when other packetization layer (UDP/RAWIP)
> 
> 
> uses this PMTU information, we must notify about this PMTU information to
> Application layer which is using UDP/RAWIP as packetization layer.
> 
> This implementation scenario is missing in RFC 1981.

	are you talking about API, or any other protocol interactions?
	please clarify.

	in either case.
	- with multicast, it is very difficult to perform effective PMTUD,
	  so applications are implemented using minimum MTU (1280).
	- with unicast, applications either use minimum MTU (1280), or
	  rely on kernel layer fragmentation mechanism.

itojun

--------------------------------------------------------------------
IETF IPv6 working group mailing list
ipv6 at ietf.org
Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------