Re: QoS mapping

On Aug 3, 2005, at 5:34 PM, Ben Greear wrote:

> John T. Kamenik wrote:
>
>> On Aug 3, 2005, at 4:58 PM, Ben Greear wrote:
>>
>>> John T. Kamenik wrote:
>>>
>>>
>>>> I have a linux based bridge/router.  On one side is a VLAN   
>>>> network,  and on the other an Ethernet network.  The VLAN  
>>>> network  uses the  user_priority field in the VLAN header to  
>>>> perform  various forms of  QoS.  The ethernet network does a  
>>>> similar thing  with the IP ToS  bits.  Is there an easy way to  
>>>> map the ToS bits  to user_priority and  visa versa?  And the  
>>>> solution cannot be "use  a Cisco" :).
>>>>
>>>>
>>>
>>> I'm sure the linux iptables code can somehow do the translation
>>> for you...but I don't know the exact details...
>>>
>>>
>> Iptables is what I thought about using first.  However, iptables  
>> does  not have an understanding of VLANs.  At least not to my  
>> knowledge.   This means that iptables has no knowledge of the  
>> user_priority field  and therefore cannot map to or from it.
>>
>
> Get VLAN to map .1q to skb->priority, and get ip tables to map skb- 
> >priority
> to ToS.  (and vice versa).
>
> Ben

I couldn't find how IP tables could map to/from skb->priority.  Is  
that what Marking a packet does, or is there something more obvious  
that I am just not seeing?  Also, will changing the skb-priority  
screw-up the rudimentary QoS that Linux uses it for?

John