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Mitel QOS Requirements 1

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J001

Technical User
Mar 23, 2007
51
GB
Hello,

We are looking to implement Mitel IP Phones on our Cisco LAN switches. Does anyone know the answers to the following questions please ?

1) How are voice packets marked (DSCP / COS)
2) How are signaling packets marked (DSCP / COS)
3) What protocol / port does voice packets use
4) What protocol / port does signaling packets use
5) What is the maximum expected bandwidth required per phone for voice
6) What is the maximum expected bandwidth required per phone for signaling.

Are there any other specific details about the IPT solutions integration into a Cisco network you can provide?


Many Thanks,

Jay
 
I'll start some answers...

1. Voice packets have DSCP values filled in, this is configurable from the system level.
2. Signaling is the same, however I'm not sure which signaling protocols it applies to.
3. RTP
4. Depends on what signaling you are talking about, but the majority is proprietary internally.
5. G711 is the worst case, which runs at 64Kbps
6. Signaling BW is near negligible in my mind, but I'm not a network guy.
 
Hi Irwin,

Do you have QOS values /settings please ?

Jay
 
The QOS (DSCP) values are whatever you set them to. What value to set them to depends on your network. Cisco has a lot of documentation on this. In most cases the default should be fine.
 
The Default DSCP is 46

Bandwidth usage is better estimated using 100K per phone. The Engineering guide can be more specific.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.
 
Default DSCP value is 46 which is EF in Cisco notation.

Signaling marked DSCP26 or TOS3

Be avare that some of the old phones ignore settings and mark all the traffic with DSCP 44, so you have to remark it on the edge routers.

Signaling is proprietary MiNET protocol.

Consider 80kbps per call on G.711 and 36kbps on G.729 codec. Jitter should be less then 30ms or at least should not increase dramaticaly, so adaptive de-jitter system will be able to catch-up with it.

 
Vlan programming should suffice.
What model of Cisco? Is it POE?

Dave

You can't believe anything you read... unless of course it's this.
 
Canuckvoip,

We don't use voice VLAN in most of the installations.
I don't see how vlan programming can help with QoS. Plus PoE has nothing to do with QoS.
 

Hello Slapin,

If Signaling marked for Mitel as DSCP26 or TOS3 do we need to reserve AF31 for Mitel Signalling on our QOS Policy ?

At the moment we CS3 reserved fo call signalling ?

See note below :-


Originally, Cisco IP Telephony equipment marked Call-Signaling traffic to DSCP AF31. However, the assured forwarding classes, as defined in RFC 2597, were intended for flows that could be subject to markdown and aggressive dropping of marked-down values. Marking down and aggressively dropping Call-Signaling could result in noticeable delay to dial tone (DDT) and lengthy call-setup times, both of which generally translate into poor user experiences.
Therefore, the QoS Baseline changed the marking recommendation for Call-Signaling traffic to DSCP CS3 because Class-Selector code points, defined in RFC 2474, are not subject to such markdown and aggressive dropping as Assured Forwarding Per-Hop Behaviors are.
Some Cisco IP Telephony products already have begun transitioning to DSCP CS3 for Call-Signaling marking. In this interim period, both code points (CS3 and AF31) should be reserved for Call-Signaling marking until the transition is complete.


 
jay, you should just be able to set the signaling DSCP value to 24 (CS3) in ESM. The value of 26 (AF31) is just the default.
 
Slapin, I need to question your previous comments:

We don't use voice VLAN in most of the installations.
I don't see how vlan programming can help with QoS.

In my case I always use vlaning. It is the simplest method to implement QOS for layer 2. If a customer of mine refuses to implement Vlan'ing, I refuse to troubleshoot voice quality issues.

Your statement and my statement seem to be in conflict. Please explain.



*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.
 
Thanks kwb,
You beat me to it...
Vlan is all we use too. On a HP switch three commands or so is all it takes and away you go!
Additionally, on the HP if you implement LLDP, you don't even need the corporate DHCP server in play for a phone to boot up (wonderful for greenfield installs and system moves).
Slapin,
Vlan uses priority values from 1 to 7. 7 being the highest priority.
Normally we set the computer network as a 1, and the voice vlan as a 6. On a 100meg network, the computer gets all 100 meg until the phone goes off hook and at that point the 100k or so for the phone gets priority.

The reason I asked if the Cisco had POE was to find out if there was an opportunity to get a nice/easy to program/lifetime warranty HP in there!

Dave


You can't believe anything you read... unless of course it's this.
 
VLAN will affect your QoS on L2 if you have a computer connected behind the phone or you have an uplink to your core via trunk port.

When you have just flat L2 network without trunk ports QoS is not affecting frame forwarding process.



For large sites we do use L2 QoS and whole 9 yards.

For medium size we segregate voice and data segments and use flat voice and flat data networks. Each router has two ethernet interfaces and at least one WAN interface. That means that we avoid IP interfaces on VLAN sub-interfaces due to performance issues in some situations.

For small sites we use a single network but separate ports for voice and data, so all devices connected via access ports and no trunking. We use El-cheapo PoE switches without any problems.
Life is good. Keep it simple :)
 
Slapin, Thanks for clarifying.

Separate networks if you can afford the extra gear is sufficient without Vlan'ing.

I rarely work on systems with less than 100 stations so separate networks can get pretty expensive.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.
 
kwbMitel,
I'm just commenting post with a statement that vlan config is just enough for everything which is not true.

jay,

If your netwhor already provisioned for CS3 just classify AF31 and remark it to CS3 on WAN routers. It will not affect anything else.

Following is a table which you can use for mapping and remarking
Code:
ToS (dec) ToS (hex) ToS (bin) ToS Precedence (bin) ToS Precedence (dec) ToS Precedence Name ToS Delay Flag ToS Throghput Flag ToS Reliability FLag DSCP (bin) DSCP (hex) DSCP (dec) DSCP Class 
0 0x00 00000000 000 0 Routine 0 0 0 000000 0x00 0 none 
32 0x20 00100000 001 1 Priority 0 0 0 001000 0x08 8 cs1 
40 0x28 00101000 001 1 Priority 0 1 0 001010 0x0A 10 af11 
48 0x30 00110000 001 1 Priority 1 0 0 001100 0x0C 12 af12 
56 0x38 00111000 001 1 Priority 1 1 0 001110 0x0E 14 af13 
64 0x40 01000000 010 2 Immidiate 0 0 0 010000 0x10 16 cs2 
72 0x48 01001000 010 2 Immidiate 0 1 0 010010 0x12 18 af21 
80 0x50 01010000 010 2 Immidiate 1 0 0 010100 0x14 20 af22 
88 0x58 01011000 010 2 Immidiate 1 1 0 010110 0x16 22 af23 
96 0x60 01100000 011 3 Flash 0 0 0 011000 0x18 24 cs3 
104 0x68 01101000 011 3 Flash 0 1 0 011010 0x1A 26 af31 
112 0x70 01110000 011 3 Flash 1 0 0 011100 0x1C 28 af32 
120 0x78 01111000 011 3 Flash 1 1 0 011110 0x1E 30 af33 
128 0x80 10000000 100 4 FlashOverride 0 0 0 100000 0x20 32 cs4 
136 0x88 10001000 100 4 FlashOverride 0 1 0 100010 0x22 34 af41 
144 0x90 10010000 100 4 FlashOverride 1 0 0 100100 0x34 36 af42 
152 0x98 10011000 100 4 FlashOverride 1 1 0 100110 0x26 38 af43 
160 0xA0 10100000 101 5 Critical 0 0 0 101000 0x28 40 cs5 
184 0xB8 10111000 101 5 Critical 1 1 0 101110 0x2E 46 ef 
192 0xC0 11000000 110 6 InterNetworkControl 0 0 0 110000 0x30 48 cs6 
224 0xE0 11100000 111 7 NetworkControl 0 0 0 111000 0x38 56 cs7

 
Thank you all for your comments !
 
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