From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: PMTU issues due to TOS field manipulation (for DSCP) Date: Wed, 10 Dec 2003 12:30:39 -0800 Sender: netdev-bounce@oss.sgi.com Message-ID: <3FD7826F.1050308@us.ibm.com> References: <20031210203433.3747b7fd.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "Kevin W. Rudd" , davem@redhat.com, kuznet@ms2.inr.ac.ru, netdev@oss.sgi.com, chester.f.johnson@intel.com Return-path: To: Andi Kleen In-Reply-To: <20031210203433.3747b7fd.ak@suse.de> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Andi Kleen wrote: > I don't think the network users will be very happy if you require changing all > end hosts this way. How about the following hack? For DF=1 packets > the ipid field is useless. When you rewrite the TOS to DSCP save > the old TOS in the ipid field. When you see an ICMP fragment required > message with the right DSCP on the router restore the old TOS from the ipid > field. Wouldnt this require changes at the both ends, router and host? How would we sync? thanks, Nivedita