From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Friesen Subject: Re: Fw: issues with SO_PRIORITY and IP_TOS Date: Tue, 04 Nov 2003 12:02:45 -0500 Sender: netdev-bounce@oss.sgi.com Message-ID: <3FA7DBB5.1090500@nortelnetworks.com> References: <200311041233.PAA15518@yakov.inr.ac.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , jmorris@redhat.com, hadi@znyx.com, netdev@oss.sgi.com Return-path: To: kuznet@ms2.inr.ac.ru Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org kuznet@ms2.inr.ac.ru wrote: >>Currently, for me to send a packet with IP precedence bits set to a >>nonzero value *and* vlan priority set to the same value, I have to do >>the following: >> >>int opt = PRIORITY << 5; >>setsockopt(mysocks[i], SOL_IP, IP_TOS, &opt, sizeof(opt)); >>opt = PRIORITY; >>setsockopt(mysocks[i], SOL_SOCKET, SO_PRIORITY, &opt, sizeof(opt)); > Hmm.. This is kinda nice. IP_TOS sets real TOS bits without any funny > shifts and masks, but with some reasonable access control, SO_PRIORITY > sets priority. TOS and PRIORITY are not related. If that were the case, I'd be happy. However, when you set the TOS bits (which really sets the whole 8-bit field, rather than just the 4 TOS bits), the kernel also sets the socket priority but only uses the TOS bits to do so. If we're going to set the whole 8-bit field, wouldn't it make sense to use the priority bits to set the priority? Or even leave the socket priority totally alone? This is why I proposed the IP_DSCP option which would have sane handling of the socket priority when setting the DSCP value. > I do not even think that IP_DSCP makes sense in diffserv environment. > Packets are marked according to DS rules, not according to desire > of particular user. If root wants to send out a packet with particular DSCP settings, doesn't it make sense to make that option available? It's a field in the IP packet header, we should be able to set it with an IP option. Chris -- Chris Friesen | MailStop: 043/33/F10 Nortel Networks | work: (613) 765-0557 3500 Carling Avenue | fax: (613) 765-2986 Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com