[asterisk-users] Re: Setting QOS settings in asterisk and/or CentOS?

[Steven]

I found this command if your Cisco switches support it:
"auto qos voip trust"
You set this on each interface.
It automatically prioritizes all SIP and skinny traffic, but not iax.

There is also "auto qos voip cisco-phone". This one can detect a Cisco phone and prioritize it.

I just have to figure out how to verify that it is actually doing anything.

-- 
-- 
Steven

http://www.glimasoutheast.org



"Rich Adamson" <radamson at routers.com> wrote in message news:4514B168.8070502 at routers.com...
> Nick Hoffman wrote:
>> On Sat September 23 2006 06:14, Bob Amen <amen at oreilly.com> wrote:
>> <snip>
>>> which sets the TOS bit on all IAX, SIP and RTP packets. Using iptables
>>> means that we can set up our rules on the router without using ACLs. Our
>>> Cisco Cookbook (http://www.oreilly.com/catalog/ciscockbk/) has a nice
>>> section on QoS (Chapter 11) and an appendix on TOS, etc. The author
>>> advises not to use ACLs when possible as they take more CPU in the
>>> router to implement and on a heavily loaded router can cause packet
>>> delays. So here's what our config looks like:
>> <snip>
>>> Cheers,
>>> Bob
>>
>>
>> Hi Bob. I'm new to TOS and DSCP, but after going over your and Rich Adamson's responses to Steve BerkHolz's question, I read up 
>> about them.
>>
>> With what you wrote above, does this mean that your Cisco router(s) deny, allow, and route traffic based on TOS/DSCP flags, and 
>> you don't bother with traditional ACL rules like below?:
>>     access-list 123 permit udp 1.2.3.4 ...
>
> ACL's in cisco hardware can be used for pattern matching in addition to the old permit, deny, etc, functions.
>
> Here's a working example from a cisco 1750 with QoS:
>
> class-map match-all voice-rtp
>   match access-group 103
> class-map match-all www-traffic
>   match access-group 105
> !
> !
> policy-map voice-policy
>   class voice-rtp
>     priority percent 40
>   class www-traffic
>    bandwidth percent 30
>   class class-default
>    fair-queue
>
> access-list 103 permit ip any any dscp cs3
> access-list 103 permit ip any any dscp ef
> access-list 103 permit ip any any tos min-delay
> access-list 103 permit ip any any tos 12
> access-list 105 permit tcp any eq www any
>
> In the above, any packet matching the access-list 103 gets treated as a "voice-rtp" class, and in the policy map, is acted upon as 
> "priority" (which means low latency queue) and can use up to 40% of the interfaces bandwidth.
>
> The "bandwidth 384" statement on the interface "is" used by QoS to determine how much is actually going to be used for voip.
>
> interface Dialer0
>  bandwidth 384
>  ip address negotiated
>  encapsulation ppp
>  dialer pool 1
>  dialer-group 1
>  service-policy output voice-policy
>  ppp pap sent-username xxxxx_dsl password 7 136775499987
>
> That bandwidth statement should be the "actual" amount of bandwidth available and not the value that your dsl/broadband provider 
> says they provide.
>
> Once the policy map is implemented, one can review the operational statistics by doing something like this:
> C1750#show policy-map interface dialer0
>  Dialer0
>
>   Service-policy output: voice-policy
>
>     Class-map: voice-rtp (match-all)
>       1441504 packets, 191386680 bytes
>       5 minute offered rate 0 bps, drop rate 0 bps
>       Match: access-group 103
>       Weighted Fair Queueing
>         Strict Priority
>         Output Queue: Conversation 136
>         Bandwidth 40 (%)
>         Bandwidth 153 (kbps) Burst 3825 (Bytes)
>         (pkts matched/bytes matched) 0/0
>         (total drops/bytes drops) 0/0
>
>     Class-map: www-traffic (match-all)
>       484061 packets, 341420115 bytes
>       5 minute offered rate 0 bps, drop rate 0 bps
>       Match: access-group 105
>       Weighted Fair Queueing
>         Output Queue: Conversation 137
>         Bandwidth 30 (%)
>
> Also, by doing the following:
> C1750#show access-list 103
> Extended IP access list 103
>     permit ip any any dscp cs3
>     permit ip any any dscp ef (1680 matches)
>     permit ip any any tos min-delay (808709 matches)
>     permit ip any any tos 12 (1 match)
>
> one can "see" which piece of an access list is being matched. One can also see that both TOS and DSCP definitions can be used 
> within the same access list. Its kind of a handy way to ensure voip phones and asterisk are properly configure and thus properly 
> treated from a QoS perspective.
>
> It should also be noted the above router is running v 12.2(4)T7 code. Cisco has made several changes to the syntax and parameters 
> implemented in each version in the last few years.  In the newer IOS versions (for both switches and routers), the syntax and 
> parameters are becoming much more standardized across all product lines.
>
> The OP was specifically asking about QoS on a cisco switch, and without researching exactly what was implemented in "his" switch, 
> there really isn't any way to give him a QoS template that would be accurate. For example, if I posted something that worked in 
> the 12.4 code, its highly likely not to be acceptable syntax for 12.1 or 12.2.
>
> Whether one uses access lists to do pattern matching is mostly immaterial "except" on a heavily loaded router. In my case, the 
> processor utilization looks like:
> C1750#show proc
> CPU utilization for five seconds: 1%/0%; one minute: 1%; five minutes: 1%
>
> where lengthy access lists would have almost zero impact.
>
> For those that have read this far, it should be noted the implementation is a 3-queue policy (one for rtp, one for www, and one as 
> the default). If the traffic for the rtp queue is low (or none), the unused bandwidth is automatically made available to other 
> lower priority queues. In other words, the allocation of bandwidth to the various queues only occurs when demand is greater then 
> the bandwidth available. Also, QoS can only be applied to "outbound" interfaces; inbound QoS must be done at the isp.
>
> Rich
>
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