altq for vlans?

Gilbert Tsang gtsang at
Sat Jul 23 02:07:20 GMT 2005

   I believe the solution is not patching ALTQ to the VLAN driver, but
   rather make ALTQ recognize rules that classify according to fields in
   Layer 2 header (fields such as VLANid and Priority, other than just
   src/dst addr/port and protocol in IP header). For example, build
   filter rules that specify priority tracking according to the 3-bit
   field in the VLAN tag as per 802.1p.
   For example in /etc/altq.conf:
   interface vx0 bandwidth 100M cbq
   class cbq vx0 root_class NULL pbandwidth 100
   class cbq vx0 vlan1_class root_class pbandwidth 80
       filter vx0 cs1_class vlan1_class vlanprio 6 # priority 6 takes
   more bandwidth
   class cbq vx0 vlan2_class root_class pbandwidth 15
       filter vx0 cs2_class vlan2_class vlanprio 4 # priority 4 takes
   less bandwidth
   The discussion (patch) back then is good for a FreeBSD configured as
   end-host, but not as a MAC bridge:
   Regards, Gilbert Tsang.
   Max Laier wrote:

On Sunday 13 February 2005 22:36, David Gilbert wrote:

Has anyone considered patching the vlan driver to support altq?  I
gather that since tun works, so should vlan.

This should be a FAQ.  Anyway,  here is the story:

While you can do ALTQ queueing on vlan interfaces the usefulness of this is
very little.  If the physical interface supports ALTQ it is *always* better
to do the queueing there.  If the physical interface does not support ALTQ it
must be patched.




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