Per-route MTU?

[Skip Ford]

When specifying the MTU of a route, packets larger than the MTU
are still sent...


$ route -n get 10.10.6.1
   route to: 10.10.6.1
destination: default
       mask: default
    gateway: 192.168.1.1
  interface: ed0
      flags: <UP,GATEWAY,DONE,STATIC>
 recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount	 mtu	 expire
       0	 0	   0	     0	       0	 0	1492	     0


$ sudo ping -D -n -c 1 -s 1472 10.10.6.1
PING 10.10.6.1 (10.10.6.1): 1472 data bytes
36 bytes from 192.168.1.1: frag needed and DF set (MTU 1492)
Vr HL TOS  Len	 ID Flg  off TTL Pro  cks      Src	Dst
 4  5  00 dc05 e586   0 0000  40  01 7de5 192.168.1.2  10.10.6.1

--- 10.10.6.1 ping statistics ---
1 packets transmitted, 0 packets received, 100% packet loss


Why doesn't this host recognize that 1500 is too large of a packet
to send to the default destination based on the MTU of the route
being 1492?

Am I doing something wrong?...or misunderstanding something?

$ uname -r
6.0-CURRENT

$ sysctl -a | grep mtu
net.inet.tcp.path_mtu_discovery: 1

The route's MTU was set using "-lock -mtu 1492".

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