netdev - Re: [PATCH 00/11] Add basic VLAN support to bridges

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Date:	Sat, 15 Dec 2012 15:52:02 -0500
From:	Vlad Yasevich <vyasevic@...hat.com>
To:	Jamal Hadi Salim <jhs@...atatu.com>
CC:	Stephen Hemminger <shemminger@...tta.com>,
	David Miller <davem@...emloft.net>, or.gerlitz@...il.com,
	netdev@...r.kernel.org, mst@...hat.com, john.r.fastabend@...el.com
Subject: Re: [PATCH 00/11] Add basic VLAN support to bridges

On 12/14/2012 04:59 PM, Jamal Hadi Salim wrote:
> On 12-12-14 11:50 AM, Vlad Yasevich wrote:
>>
>> Interesting.  But, but how complex would be be to configure a vlan
>> filter for say 10 different vlans,
>
> Shouldnt be hard. At the simple level you need one rule per VLAN.
> I am assuming only one vm per vlan and that you can key on something
> in the header.
>
>> each one of them only permitted
>> to be forwarded to their respective VM.
>
> Again assuming something in the header is going to say "this packet
> is allowed to go to this VM", a MAC address, an IP src/destination
> etc, correct?

The VLAN id in this case is what should decide where the packet is going.

>
>   Oh, and Vlan tags should
>> be stripped when they are being forwarded.
>
> Assuming they are not already stripped at vnetx,
> you could write a very simple action (probably one page of code) to
> strip vlans and do everything at br0;
> Your filter finds them at br0, your action strips them and pipes to
> another action that redirects to the correct device. i.e in unix speak:
> filter at br0 for VMx | strip vlan tag | redirect to vnetx

So you would completely bypass the bridge?  Not sure how much I like 
that since what would happen if 2 VMs are to share VLAN.  In such a 
case, broadcasts/multicasts only should only get forwarded to both of
these VMs.

I guess we could add the filters on the vnetx interfaces (which are just
taps).  Then its 2 filters per vlan (1 ingress 1 egress).  Need to think 
about this a bit.

Thanks
-vlad
>
> At the very minimal you need to identify those packets and that depends
> where you want to deploy the policy.
> If you deploy at the br device, you will see the raw packet i.e the vlan
> header wont be stripped.
> i.e youd have to enter some u32 rule with protocol "protocol 802.1q"
> If you deploy at each vnetx device assuming it is a vlan device, you
> wont see the vlan headers and you'll have to key on something else on
> the header "protocol ip"
>
> cheers,
> jamal
>
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