[Asterisk-Users] QOS / Cisco / Asterisk

Jeffrey C. Ollie jeff at ollie.clive.ia.us
Mon Jan 3 14:57:54 MST 2005


On Mon, 2005-01-03 at 13:53 -0600, Matt Schulte wrote:
> We're trying to PQ (Priority Queue) packets on a Cisco using ACL's. What
> we're trying to avoid is hardcoding the IP address in the ACL. We were
> trying to match by TOS set by Asterisk however it seems we've run into a
> snag where the packet TOS tends to get reset somewhere on our network.
> Has anyone had this issue? We're running Cisco everywhere inbetween
> (even the switches). Is there an alternative way to match these? We've
> thought of by port but that's kind of ad-hoc IMHO.

If the TOS is getting reset somewhere out there you need to go through
all of your switches and make sure that none of them are messing with
the TOS.  Unfortunately doing QOS on Cisco switches is a black art as
the necessary commands depend on the hardware and the IOS version (or
CatOS version if you are unlucky).  Check the documentation for your
switches for the "mls qos trust" command.

Cisco routers, on the other hand, don't mess with IP TOS/DSCP labels
unless you specifically ask them to.

Jeff

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