On 9/11/06, Ben Greear <greearb at candelatech.com> wrote:
> Andy Gospodarek wrote:
> > On 9/11/06, David Kimdon <david.kimdon at devicescape.com> wrote:
> >> Hi,
> >>
> >> The attached patches enables the bridge to filter and forward packets
> >> according to their IEEE 802.1q headers. The goals behind this change
> >> include :
> >>
> >> - Enable running STP on 802.1q tagged networks. STP packets
> >> must be untagged. It isn't obvious how else to enable STP
> >> with the current bridge and vlan code.
> >> - Add native support for an untagged vlan. Currently an untagged
> >> vlan can be implimented using ebtables or similar.
> >> - On devices bridging a large number of interfaces across various
> >> vlans this significantly simplifies configuration and, depending on
> >> configuration, can improve performance.
> >>
> >> Comments appreciated,
> >>
> >> David
> >
> >
> > David,
> >
> > It looks like this code specifically ignores (which is OK for now) and
> > clears (which is not OK) the frame's 802.1p priority. Have you tested
> > priority-tagged frames to see if they are passed correctly? It seems
> > like you should consider adding another field to the sk_buff structure
> > so priority of the incoming frame can be tracked as well as add logic
> > to br_vlan_output_frame and br_vlan_input_frame so the tag is saved.
> > Something like this would probably be fine:
> >
> > Signed-off-by: Andy Gospodarek <andy at greyhouse.net>
> >
> > --- ./include/linux/skbuff.h.gospo 2006-09-11 14:41:54.000000000 -0400
> > +++ ./include/linux/skbuff.h 2006-09-11 14:43:27.000000000 -0400
> > @@ -297,6 +297,7 @@ struct sk_buff {
> > __u32 nfmark;
> > #endif /* CONFIG_NETFILTER */
> > #ifdef CONFIG_BRIDGE_VLAN
> > + unsigned int vlan_priority;
> > unsigned int vlan;
> > #endif
>
> SKB bloat is not good for performance. You can store the priority and the VID in
> a single 32-bit number with room to spare...
>
> The skb->priority is also a possible place to store the VLAN priority.
Good. I didn't like the idea of increasing the bloat factor of an skb.
>
> The actual VLAN code has a mapping from vlan-priority -> skb priority on ingress,
> and another mapping of skb->priority -> vlan-priority on egress. You probably
> don't need to worry about this mapping for a bridge, however.
If the bridge destroys your existing priority then that's bad however.
Am I seeing this wrong or will this not reset bridged frames to
priority zero in the case where untagged frames need to be given a tag
as they are bridged?
>
> Ben
>
> --
> Ben Greear <greearb at candelatech.com>
> Candela Technologies Inc http://www.candelatech.com
>
>
