>I'm submitting this fast-track for Erik Nordmark, it times out on
>10/02/2009. The release binding is Patch.
>
>Background:
>----------
>
>Since Solaris 2.0 we have enabled path MTU discovery by default
>including for UDP and RAWIP sockets. The addition of IP_DONTFRAG
>[PSARC/2009/494] allows applications to control this.
>
>Solaris implements traceroute -F ("dontfrag") to disable path MTU
>discovery for traceroute. But this is documented as not working in
>zones. And the implementation doesn't do it for IPv6 at all.
>
>BSD implements a -D option to ping(1m) to enable path MTU discovery just
>like "-F" does it for traceroute. Solaris does not currently implement
>this option.
>
>Details:
>-------
>
>This case is to introduce ping -D in Solaris and remove the limitations
>for traceroute -F..
>
>The behavior of ping and traceroute when these options (-D and -F
>respectively) are not specified is unchanged.
>
>
> Exported Interfaces
> -------------------------------------------------------------
>
> Interface Classification Comments
> -------------------------------------------------------------
>
> ping -D option Committed ping(1M)
> ping -F option Committed traceroute(1M)
> -------------------------------------------------------------
"traceroute -F option", surely?
>
>Man page updates:
>================
>
>Add this text to ping(1M):
> -D
> Turn off path MTU discovery. For IPv4 this means setting
> the Don't Fragment bit. For IPv4 and IPv6 this means to
> not allow fragmentation as the datagrams are sent. If
> the data_size exceeds the MTU, then ping may report
> that sending failed due to Message too long.
>
>Change the text in traceroute(1M) from:
> -F
>
> Set the "don't fragment" bit. This option is valid only
> on IPv4. When specified from within a shared-IP zone,
> this option has no effect as the "don't fragment" bit is
> always set in this case.
>to:
> -F
> Turn off path MTU discovery. For IPv4 this means setting
> the Don't Fragment bit. For IPv4 and IPv6 this means to
> not allow fragmentation as the datagrams are sent. If
> the packetlen exceeds the MTU, then traceroute may
> report that sending failed due to Message too long.
>---
This sounds wrong. If you set the "don't fragment bit" then you ARE doing
path MTU discovery. I think we only do this on TCP/IP and we don't
do this for ICMP (ping) or UDP (traceroute).
Casper
