With KAME the MTU size of the loopback interface became strange and is actually dependend on the architecture. I see no point in all this just go back to the way it was long long long ago and just use 32k as the MTU. AFAIK all of this was only done to test large IPv6 packets but why MHLEN and MLEN were added is still beyond my imagination.
-- :wq Claudio Index: net/if_loop.c =================================================================== RCS file: /cvs/src/sys/net/if_loop.c,v retrieving revision 1.54 diff -u -p -r1.54 if_loop.c --- net/if_loop.c 19 Apr 2014 11:01:37 -0000 1.54 +++ net/if_loop.c 12 May 2014 21:29:07 -0000 @@ -143,11 +143,7 @@ #include <net/bpf.h> #endif -#if defined(LARGE_LOMTU) -#define LOMTU (131072 + MHLEN + MLEN) -#else -#define LOMTU (32768 + MHLEN + MLEN) -#endif +#define LOMTU 32768 int loop_clone_create(struct if_clone *, int); int loop_clone_destroy(struct ifnet *);
