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QOS with a cisco 837

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mikeleahy

Technical User
Joined
Jan 12, 2005
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266
Location
IE
hi

how do i set up qos on a cisco 837 to prioritise voice over data traffic. is it complicated
 
thanks. if i set up voip with a precendence of 5 will that give voice priority. what does this bit mean

"If the VoIP packets are generated from within the router, you may set the IP precedence to 5 for these packets by entering the ip precedence number command in dial-peer voice configuration mode as follows:


how do i know if the traffic is generated from within the router
 
Mike

Whether the voip packets are generated within the router is dependent on what the function of that router is. For instance, if you're deploying IP telephony, all the IP phones assign a precedence of 5 (usually the default) to all voice. In this instance, the router isn't generating voice traffic is simply needs to recognise (or classify) the traffic and then assign it to a priority queue.

SOme Voip implementations typically utilise voice-enabled routers which may generate voice traffic. In this instance, the router must assign or mark its traffic with a precedence of 5 so that other devices (i.e. non voice routers) can recognise it as voice traffic.

So, in summary, if you're using IP Phones, you don't need to set ip precedence on the voice packets. Step 2 onwards (in the link I provided) are the bits you are interested in.

If you aren't using IP Phones and your routers are voice-enabled, then you must mark the generated voice packets with an IP Precedence of 5. Step 1 onwards will be the bits you are interested in.

 
the phones arent ip phones i dont think. how would i know if they are??? i know these are silly questions but im not familiar with this .

The setup is as follows ::

dublin extensions were added into the pabx by the telecoms company, they put a rule on the system that any call made to these numbers be forwarded to the ip of the router, the router then just forwards all these packets alont the wan link to dublin and they are processed above. do you know from
 
the phones arent ip phones i dont think. how would i know if they are??? i know these are silly questions but im not familiar with this .

The setup is as follows ::

dublin extensions were added into the pabx by the telecoms company, they put a rule on the system that any call made to these numbers be forwarded to the ip of the router, the router then just forwards all these packets alont the wan link to dublin and they are processed above. do you know from this ino do i need step 1
 
Hi Mike

It sounds like you're running a voip setup however check a couple of your phones. If they are IP Phones, they will have an Ethernet (RJ45) connection into your switch just like any desktop PC. If the phones are still utilising their existing telephone cabling (RJ11), they're just normal phones.

Have a look at some of them and see if you can determine how their connected. Once you've got an idea, it should help you determine which configuration steps are of interest to you.
 
they are not ip phones, no rj45 jacks , just rj 11.

If you aren't using IP Phones and your routers are voice-enabled, then you must mark the generated voice packets with an IP Precedence of 5. Step 1 onwards will be the bits you are interested in.

i will be doing step 1 onwards obviously. How do i determine if the routers are voice enabled ?? I just set up the config on the routers as per the isp instructed me to do .its a pretty basic config using bgp routing.

 
Mike

This is a hard question to answer as I have no visibility of your voice/IP network. Some routers will perform different functions from a voice/IP perspective.

The info your ISP provided will likely not reflect what you're trying to do with the voice network. Configuring voip from scratch with little or no experience or training can be tricky in my opinion.

But in short, a voice router will typically have voice ports for connection to the PBX (usually a T1/E1). It will have dial-peers defined and other interesting things such as vad, crtp etc.

If this is the router the PBX is sending all it's voip traffic too and you see no mention of dial-peers etc on the config, then you'll likely need to undertake full configuration of the voice component on the device.

As I say, I don't envy you having to do this if you have little or no understanding of voice/IP networking. However I hope the following link is of use to you. It breaks down some typical voice configuration options for the 800 router.

Hope this helps
 
thanks for that. well i dont have to do it from scratch. at the moment we have 2 private circuits, one for the voice and one for the data. only voice goes over one circuit so there has been no need for QOS. we are now thinking of moving everything to go over one circuit i.e voice and data so we will have to prioritise the voice traffic to ensure it gets through.
 
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