From mboxrd@z Thu Jan 1 00:00:00 1970 From: Toshiaki Makita Subject: Re: [PATCH net 0/4] bridge: Fix problems around the PVID Date: Wed, 25 Sep 2013 02:30:18 +0900 Message-ID: <1380043818.4391.26.camel@localhost.localdomain> References: <1378808874.3988.2.camel@ubuntu-vm-makita> <20130912.160033.779509034953932316.davem@davemloft.net> <1379074013.1678.16.camel@localhost.localdomain> <523744A6.5090001@redhat.com> <1379405552.6177.31.camel@ubuntu-vm-makita> <524052FC.5010301@redhat.com> <1380023107.3162.53.camel@ubuntu-vm-makita> <52419509.1020103@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Toshiaki Makita , David Miller , netdev@vger.kernel.org, Fernando Luis Vazquez Cao , Patrick McHardy To: vyasevic@redhat.com Return-path: Received: from mail-pb0-f51.google.com ([209.85.160.51]:59581 "EHLO mail-pb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753449Ab3IXRaY (ORCPT ); Tue, 24 Sep 2013 13:30:24 -0400 Received: by mail-pb0-f51.google.com with SMTP id jt11so4891475pbb.10 for ; Tue, 24 Sep 2013 10:30:24 -0700 (PDT) In-Reply-To: <52419509.1020103@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2013-09-24 at 09:35 -0400, Vlad Yasevich wrote: > On 09/24/2013 07:45 AM, Toshiaki Makita wrote: > > On Mon, 2013-09-23 at 10:41 -0400, Vlad Yasevich wrote: > >> On 09/17/2013 04:12 AM, Toshiaki Makita wrote: > >>> On Mon, 2013-09-16 at 13:49 -0400, Vlad Yasevich wrote: > >>>> On 09/13/2013 08:06 AM, Toshiaki Makita wrote: > >>>>> On Thu, 2013-09-12 at 16:00 -0400, David Miller wrote: > >>>>>> From: Toshiaki Makita > >>>>>> Date: Tue, 10 Sep 2013 19:27:54 +0900 > >>>>>> > >>>>>>> There seem to be some undesirable behaviors related with PVID. > >>>>>>> 1. It has no effect assigning PVID to a port. PVID cannot be applied > >>>>>>> to any frame regardless of whether we set it or not. > >>>>>>> 2. FDB entries learned via frames applied PVID are registered with > >>>>>>> VID 0 rather than VID value of PVID. > >>>>>>> 3. We can set 0 or 4095 as a PVID that are not allowed in IEEE 802.1Q. > >>>>>>> This leads interoperational problems such as sending frames with VID > >>>>>>> 4095, which is not allowed in IEEE 802.1Q, and treating frames with VID > >>>>>>> 0 as they belong to VLAN 0, which is expected to be handled as they have > >>>>>>> no VID according to IEEE 802.1Q. > >>>>>>> > >>>>>>> Note: 2nd and 3rd problems are potential and not exposed unless 1st problem > >>>>>>> is fixed, because we cannot activate PVID due to it. > >>>>>> > >>>>>> Please work out the issues in patch #2 with Vlad and resubmit this > >>>>>> series. > >>>>>> > >>>>>> Thank you. > >>>>> > >>>>> I'm hovering between whether we should fix the issue by changing vlan 0 > >>>>> interface behavior in 8021q module or enabling a bridge port to sending > >>>>> priority-tagged frames, or another better way. > >>>>> > >>>>> If you could comment it, I'd appreciate it :) > >>>>> > >>>>> > >>>>> BTW, I think what is discussed in patch #2 is another problem about > >>>>> handling priority-tags, and it exists without this patch set applied. > >>>>> It looks like that we should prepare another patch set than this to fix > >>>>> that problem. > >>>>> > >>>>> Should I include patches that fix the priority-tags problem in this > >>>>> patch set and resubmit them all together? > >>>>> > >>>> > >>>> I am thinking that we might need to do it in bridge and it looks like > >>>> the simplest way to do it is to have default priority regeneration table > >>>> (table 6-5 from 802.1Q doc). > >>>> > >>>> That way I think we would conform to the spec. > >>>> > >>>> -vlad > >>> > >>> Unfortunately I don't think the default priority regeneration table > >>> resolves the problem because IEEE 802.1Q says that a VLAN-aware bridge > >>> can transmit untagged or VLAN-tagged frames only (the end of section 7.5 > >>> and 8.1.7). > >>> > >>> No mechanism to send priority-tagged frames is found as far as I can see > >>> the standard. I think the regenerated priority is used for outgoing PCP > >>> field only if egress policy is not untagged (i.e. transmitting as > >>> VLAN-tagged), and unused if untagged (Section 6.9.2 3rd/4th Paragraph). > >>> > >>> If we want to transmit priority-tagged frames from a bridge port, I > >>> think we need to implement a new (optional) feature that is above the > >>> standard, as I stated previously. > >>> > >>> How do you feel about adding a per-port policy that enables a bridge to > >>> send priority-tagged frames instead of untagged frames when egress > >>> policy for the port is untagged? > >>> With this change, we can transmit frames for a given vlan as either all > >>> untagged, all priority-tagged or all VLAN-tagged. > >> > >> That would work. What I am thinking is that we do it by special casing > >> the vid 0 egress policy specification. Let it be untagged by default > >> and if it is tagged, then we preserve the priority field and forward > >> it on. > >> > >> This keeps the API stable and doesn't require user/admin from knowing > >> exactly what happens. Default operation conforms to the spec and allows > >> simple change to make it backward-compatible. > >> > >> What do you think. I've done a simple prototype of this an it seems to > >> work with the VMs I am testing with. > > > > Are you saying that > > - by default, set the 0th bit of untagged_bitmap; and > > - if we unset the 0th bit and set the "vid"th bit, we transmit frames > > classified as belonging to VLAN "vid" as priority-tagged? > > > > If so, though it's attractive to keep current API, I'm worried about if > > it could be a bit confusing and not intuitive for kernel/iproute2 > > developers that VID 0 has a special meaning only in the egress policy. > > Wouldn't it be better to adding a new member to struct net_port_vlans > > instead of using VID 0 of untagged_bitmap? > > > > Or are you saying that we use a new flag in struct net_port_vlans but > > use the BRIDGE_VLAN_INFO_UNTAGGED bit with VID 0 in netlink to set the > > flag? > > > > Even in that case, I'm afraid that it might be confusing for developers > > for the same reason. We are going to prohibit to specify VID with 0 (and > > 4095) in adding/deleting a FDB entry or a vlan filtering entry, but it > > would allow us to use VID 0 only when a vlan filtering entry is > > configured. > > I am thinking a new nlattr is a straightforward approach to configure > > it. > > By making this an explicit attribute it makes vid 0 a special case for > any automatic tool that would provision such filtering. Seeing vid 0 > would mean that these tools would have to know that this would have to > be translated to a different attribute instead of setting the policy > values. Yes, I agree with you that we can do it by the way you explained. What I don't understand is the advantage of using vid 0 over another way such as adding a new nlattr. I think we can indicate transmitting priority-tags explicitly by such a nlattr. Using vid 0 seems to be easier to implement than a new nlattr, but, for me, it looks less intuitive and more difficult to maintain because we have to care about vid 0 instead of simply ignoring it. Thanks, Toshiaki Makita > > How it is implemented internally in the kernel isn't as big of an issue. > We can do it as a separate flag or as part of existing policy. > > -vlad > > > > > Thanks, > > > > Toshiaki Makita > > > >> > >> -vlad > >> > >>> > >>> Thanks, > >>> > >>> Toshiaki Makita > >>> > >>>> > >>>>> > >>>>> Thanks, > >>>>> > >>>>> Toshiaki Makita > >>>>> > >>>>>> > >>>>>> -- > >>>>>> To unsubscribe from this list: send the line "unsubscribe netdev" in > >>>>>> the body of a message to majordomo@vger.kernel.org > >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html > >>>>> > >>>>> > >>>>> > >>> > >>> > >>> -- > >>> To unsubscribe from this list: send the line "unsubscribe netdev" in > >>> the body of a message to majordomo@vger.kernel.org > >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > >>> > > > > >