Re: Receiving of priority tagged packets

[Eric Dumazet <eric.dumazet@gmail.com>]

Le dimanche 23 mai 2010 à 02:36 -0700, Vladislav Zolotarov a écrit :
> Hello,
> We were playing with FCoE in our labs and saw the strange behavior of Linux networking stack in regard to priority-tagged frames (the ones that have a zero VID in a VLAN tag). We saw that until we explicitly added a zero vlan interface (vconfig add ethX 0) the stack refused to accept such packets both in HW VLAN acceleration mode (skb is indicated using vlan_hwaccel_receive_skb()) and in a regular mode (skb is indicated with netif_receive_skb()).
> 
> However "IEEE Std 802.1Q, 2006 Edition DRAFT D0.1" in section 6.7 states the following: 
> 
> Each Bridge Port shall support the following parameters for use by these (EISS tagging and detagging) functions:
> 	c) an Acceptable Frame Types parameter with at least one of the following values:
> 		1) Admit Only VLAN-tagged frames;
> 		2) Admit Only Untagged and Priority-tagged frames;
> 		3) Admit All frames
> 
> So I guess this means that priority tagged frames should be accepted together with the untagged frames on the default interface ethX.
> 
> Could anyone explain, pls., what's the expected behavior of the Linux Networking Stack in regard to the priority-tagged frames and what's expected to be configured in order to start accepting them?
> 
> Thanks in advance,
> vlad

So if eth0.0 is setup, incoming vlanid=0 frames are delivered to eth0.0,
OK ? (This works in and out since commit 05423b241311c93)

Now, if eth0.0 is not setup, you believe these frames should be directed
to eth0, as if they were not tagged ?

That seems a bit strange.