VoIP and QoS Question

[dfusion]

Hi everyone. I have a question to about VoIP.

I have two sites, one in Las Vegas and one in Columbus. Las Vegas has a Nortel Option 11c and Columbus has a Nortel MICS key system. I would like to add an ITG Line Side card to the Option 11c and a Norstar VoIP Gateway to the MICS. Currently there is a point to point T1 with Cisco 2620 routers at each side. The LAN on both sides are fully switched networks running Foundry Networks Big Iron 8000 switches.

My question is in regards to QoS. Based on the Nortel literature I read, when the voice packets leave the Nortel IP card on the PBX or Norstar it automatically adds QoS (prioritization) to the packets. Does this mean I do not need to do anything to the Cisco routers as they will know when high priority (voice) packets are coming through? Or do I still need to enter some sort of configuration commands on the router so as the packets traverse the WAN they are still prioritized on the opposing LAN side? I'm a bit confused. Basically I'm trying to avoid the obvious jitter, delay, etc. and wasn't sure if when a LAN packet is prioritized if the WAN equipment still needs additional programming or if the prioritization carries over from the LAN. I appreciate any help or explanations.

Regards,
Mark

 

[senk1s]

QoS is an end to end feature - all the devices thru the route needs to be QoS enabled/ capable

 

[dfusion]

So what needs to be enabled on the Cisco 2600 routers in this particular scenario? How would I "carry out" QoS beyond the LAN side?

I appreciate the feedback.

Regards,
Mark

 

[geraldshort]

go to cisco's site and do a search for QOS with your router and IOS version. If you don't want to mess with it you can hire a remote tech to configure it for you online.

Gerald

 

[mtashiro]

You need to have end to end QoS enabled. The Nortel will mark the packets but unless the devices honor and queue the "important" packets correctly they may as well not be marked.

That said, look up LLQ on Cisco's site. Depending one what version of IOS you are using you may be able to use AutoQoS to save you some time.

Good luck.

 

[YWGMoose]

What version of QoS are you using? DiffServ, IntServ?
Cisco will honour nearly all QoS packets as long as it is told what to look for.
If using DiffServ, you will need the DSCP value and tell the Cisco to look for that.

Bear in mind as well, that most Telephone system manufacturers will not support any lack of QoS if they know it is passing through a third party device, even if it is Cisco!

 

[dfusion]

Thanks for the replies. The Cisco 2621 routers are running Version 12.1(3r)T2, RELEASE SOFTWARE (fc1).

I want to ensure I'm understanding this the correct way. The telephony systems will automatically prioritize the packets, and I would need to enable QoS on the core switches and the Cisco routers (anywhere the voice packets will traverse). I would use Diffserv on each router and switch from end to end? I'm confused at what actually "enables" QoS, and what the different types of QoS actually do? Is there one that's considered industry standard? Below is small layout of the network.



Nevada Data Center - NORTEL OPTION 11 w/ITG (Ethernet for VoIP)
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Foundry Big Iron 8000 Layer 3 LAN Switch
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Cisco 2621
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WAN (P2P T1)
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Cisco 2621
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Foundry Fastiron 4802 Layer 3 LAN Switch (Small Network at this site, hence small L3 switch)
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Ohio - Nortel Norstar Mics w/Nortel VoIP Gateway device (Ethernet, like having an ITG in an external box)

 

[MattWray]

Here is a link from Cisco about AutoQoS,

http://cisco.com/en/US/products/hw/routers/ps259/products_qanda_item09186a0080134a66.shtml

Thanks,

Matt Wray

GFH

http://www.sss-steel.com