Date: Sat, 22 Jan 2005 10:50:18 +0500 From: Boris Kovalenko <boris@ntmk.ru> To: freebsd-net@freebsd.org Subject: [PATCH] 802.1p priority (fixed) Message-ID: <41F1E99A.5070001@ntmk.ru>
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Hello! 802.1p is just a 3 bits of 802.1Q header. Based on it Layer 2 devices may assign packets to different output queues (more simple, 802.1p is QoS at Layer 2). So, You have right, this value differentiates packets within a vlan and Layer 2 device may make a decision what packets should be processed first. Of course, we may give the application the ability to set this value itself, but what to do with old applications that have no knowledge about this ability? Ok, You suppose to mark packets within PF/IPFW. Yes, the idea is good too, but what to do on routers not running any firewall software? So, may be right way will be: 1. Mark 802.1p at application level 2. Mark 802.1p at PF/IPFW level. But we shold foresee a keyword to trust application level information or override it. For example ipfw add 802.1p trust 6 on any to any ssh <-- this trust application level information and set 802.1p to 6 if it is omitted ipfw add 802.1p override 6 on any to any ssh <-- this silently set 802.1p == 6, regardless of application 3. Mark 802.1p at vlan drivers like 2 ifconfig vlan0 vlan: 100 802.1p: 6 CFI: 0 mode: trust vlandev: bge0 Here we are trusting received from low level information and set 6 if it is omitted ifconfig vlan0 vlan: 100 802.1p: 6 CFI: 0 mode: override vlandev: bge0 Here we silently set 6. How this idea is? >My letting the application handle it, I was thinking of adding a socket >option (possibly requiring privilege) to set the priority. >As to having PF/IPFW deal with it, I was thinking about two >modifications to IPFW. First, the ability to filter based on .1p tags. >You might want to peal that information off in the Ethernet >code and tag the packets so you could still inspect it at a higher >level, but maybe not. The second modification would be to give ipfw/pf >the ability to set .1p priorities on packets, ie: > >ipfw add 802.1p 6 on any to any ssh > >My concern is that 802.1p is like the TOS bits in that it >differentiates >packets within a network rather then segregating them in to networks >like 802.1Q. In a switch it makes sense to handle priorities as >separate >networks, but I'm not sure it makes sense in a host. If nothing else, >it seems to make sense to be able to set priorities on vlan >encapsulated >frames. > >I've done a little googling on 802.1p and that hardened my believe that >the application and packet filter are the places to deal with this. >I'm >downloading the standard now to take a look at it. > >-- Brooks
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