I'm trying to set up QoS for our new VoIP installation, and nothing I've read has made everything clear. The QoS and Modular QoS Command Line Interface documents helped, but I'm still a little lost.
I've identified the flows and have priority levels, but I am not familiar enough with IOS start entering commands without a little help. Hopefully one of you guys can point me to some additional resources or can lend me a hand.
Say I have three routers at three sites - 192.168.100.0/24,
192.168.105.0/24 and 192.168.40.0/24. These routers are connected together with IPs 10.1.1.1 10.1.1.2 and
10.1.1.3 respectively. Each of these three sites has a VoIP switch -
192.168.100.10 192.168.105.10, and 192.168.40.10. How do I configure QoS such that I can plug in an end point at any site and connect to any other site without problems?
I am using Inter-Tel products for our IP telephone requirements. In the most basic arrangement I'm expecting, there will be numerous model
8662 endpoints which will connect to an Inter-Tel 5400 series switch which is in turn networked to an Inter-Tel AXXESS switch. The telephones, 5400 series switch, and the AXXESS switch are all in separate physical locations. These sites are connected by ATT's Opt-E-Man service, providing low latency, 100 megabit throughput. Each site is equipped with a Cisco 2821 series router, running IOS 12.4(1r). Per the Inter-Tel documentation, these endpoints are supposed to use SIP mode for communication.
I'm not sure how much more specific you need me to get; all I'm look> > I'm trying to set up QoS for our new VoIP installation, and nothing
OK - so they are set to use SIP. SIP is the control protocol, but you also need to know how the actual voice traffic is going to be marked etc so the QoS can ID the high priority traffic.
1 diversion - a 2821 is going to struggle to "fill" a 100 Mbps pipe - so if those WAN links are contracted to run at 100 Mbps then you probably wont be able to use all the bandwidth. (if you have that, then you would be better with layer 3 switches, since they move packets in hardware and 100 Mbps is well within the available thruput).
Raw router performance:
formatting link
total thruput for a 2821 (under ideal conditions, with nice big packets) is
87 Mbps - but you have up to 200 Mbps of WAN (full duplex link).
Voice isnt "nice" from a router perf point of view - a Cisco IPT voice stream is typical, and is 50 small packet/sec in each direction, and is finicky about drops and timing jitter.
More importantly for your voice traffic - anything more than simple FIFO packet forwarding will not get near these numbers, and overloaded routers will not process QoS well (ie drops under overload may include voice packets).
if you have voice traffic then i would not want to run more than 10 to 20 Mbps total traffic thru one of these routers. You need to do some testing once you have a working setup to check.....
you need to know how to ID the IP telephony real time traffic (ie the voice samples) to set up the cisco gear to recognise them.
the Cisco modular QoS stuff not unreasonably assumes you use Cisco IPT - so if your system uses the same traffic types / Diffserv markings etc then great (and Cisco does seem to conform to some defaults in wide use) - otherwise you are looking at coming up with a set of manual config info.
i suggest you ask the IPT supplier for "best practice" config info for Cisco routers and switches.
After all it is probably the default environment they need to live in, so if they dont know (or cannot tell you) that is a real bad sign for ongoing support.......
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