RE: (ngtrans) I-D ACTION:draft-ietf-ngtrans-mech-v2-01.txt

["Dave Thaler" <dthaler@windows.microsoft.com>]

> From: Fred Templin [mailto:osprey67@yahoo.com]
[...]
> Conclusion - the fixed interface MTU of 1280 bytes suggested in the
> MECH text is too small. I suggest it be changed to 1428 (1500 minus
> 72 for IPv4/VPN encaps).

I'm told by our VPN folks here that the MTU on our IPv4 VPN 
interfaces is 1400.  This was based on overhead for 
IP+AH+ESP+UDP+L2TP+PPP, and still fitting in an Ethernet MTU.

Hence to avoid gratuitous fragmentation, we'd want the MTU
inside an IPv6-over-IPv4 tunnel interface to be at most 1380.

-Dave