Re: [mpls-linux-general] MPLS and 802.11e

[Jeremy J. <je...@co...>]

There was a time when madwifi had it's own classifying code, which I
disagree with.  IMO, it should respect the skb_priority field, which can
be set by iptables or generic networking stack code.

in net/ipv4/ip_input.c::ip_forward()

skb->priority = rt_tos2priority(iph->tos);

I believe the correct implementation might be for MPLS to set
skb->priority. Perhaps in addition to outgoing interface/label, there
should be a priority attribute for label switching, what would get
copied here for each packet as it is label-switched.

In madwifi 0.9.4 net80211/ieee80211_output.c::ieee80211_classify() you
have the details, if WME is enabled, then VLAN priority tag and IP TOS
are mapped hardcoded to skb-> priority, overwriting the linux network
core's setting.  If the packet is not VLAN or IP, it's prio is
overwritten always to WME_AC_BE.  This is the problem you're having with
MPLS.  It would be interesting to see how the ath5k driver does this,
since madwifi-ng is obsolete.

I think wifi code should just use the skb-> priority, instead of
implementing it's own policy in 802.11 stack.  It's not feasible to
duplicate the decoding of priority from all possible protocols, and
having it hardcoded in wifi driver.

On Thu, 2008-06-05 at 12:20 +0200, Jorge Boncompte [DTI2] wrote:
> Luca Pilosu escribió:
> > Do you mean it could be that MadWifi driver doesn't "understand" the 
> > meaning of the packet's fields but only extracts them with some kind of 
> > fixed-size masks?
> 
> 	Driver is not responsible of classifying packets, protocol stack 
> (net80211) is. You have to look at function ieee80211_classify() on the 
> file ieee80211_output.c. There you'll see that it only classifies VLAN 
> or IP packets. You have to modify and teach that function how to 
> classify MPLS/IP packets.
> 
> 	Regards,
> 
> 	-Jorge
> 
> ==============================================================
> Jorge Boncompte - Ingenieria y Gestion de RED
> DTI2 - Desarrollo de la Tecnologia de las Comunicaciones
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Jeremy Jackson
Coplanar Networks
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