Mitel SX 200 IP NODE Instructions Guide

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 LAN Design Guidelines for the Implementation of SX-200 IP NODE
This Technical Bulletin is intended for Customer Service and Installation personnel involved in the installation of Mitel
Networks SX-200 IP NODE.
Issued January, 2003
NOTICE
The information contained in this document is believed to be accurate in all respects but is not warranted by Mitel
Networks Corporation (Mitel).  The information is subject to change without notice and should not be construed in any way
as a commitment by Mitel or...

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1. NETWORK GUIDELINES FOR VOICE OVER IP INSTALLATIONS .......................................................................... 3
1.1 EXECUTIVE SUMMARY............................................................................................................................................ 3
2. SUMMARY OF GUIDELINES ...................................................................................................................................... 
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3. GUIDELINES AND EXPLANATIONS...

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1.  Network Guidelines for Voice over IP Installations
The following information is to be used in determining the suitability and requirements for a Voice over IP installation. The
MITEL Networks SX-200 IP NODE will be used to illustrate some of these areas.
The contents of this document should be used in assessing the capabilities of a particular network with respect to
maintaining voice quality and usability of the IP-Phones and associated controllers.
Networks by definition do not always follow...

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•  Only one LAN connection should be made from the ICP controller to the network
•  The IP NODE should be located behind a network Layer2 switch
•  Ensure that the PPS rate of the routers and switches is adequate for the amount of voice traffic expected
•  Wherever possible, provide the most bandwidth. Use Full duplex in preference to Half duplex.
•  If the network consists of multivendor units, do they all inter-work correctly?
•  Use MTU on routers especially for slower speed links (anything less...

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Although some packet loss can be handled on an ongoing basis, if the loss becomes bursty the user will start to notice.
Thus a network with 0.1% packet loss over time will sound a lot different to one that encounters a burst loss or 3 or more
packets, but still at 0.1% loss
3.2.5 Available Bandwidth
If a connection is rated at a particular bandwidth, this does not necessarily mean that all of this bandwidth is available.
Connections between LAN and WAN network devices include a certain amount of...

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devices could equally be doing the same. Use of a switch is almost the same as having multiple networks. Network
efficiency is greatly improved, as well as network management.
Since connections in a switched network are typically point to point, there is also the possibility of configuring the
connection to be Full Duplex. This virtually doubles the bandwidth, since data can be sent and received at the same time.
In a half duplex environment data can only be sent or received sequentially. Equipment...

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The table, below, shows typical wire data rates for different protocols and LAN/WAN interfaces. Note, for example, that a
Half-Duplex link uses twice the bandwidth on the connection than a similar Full Duplex connection for the same voice
connections. This is because the Half-Duplex connection is shared with other devices and one transmitter must also send
data on the receive path for all other devices to hear.
From the statement some recommendations ensue:
•  Use Full Duplex wherever possible. This...

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CODEC TypeMOSLAN Bandwidth
G.711 4.3 ~100kbits/sG.729 4.0 ~40kbits/s
As can be seen the G.711 CODEC gives the better speech quality, but also requires more bandwidth in order to achieve
this. For this reason it may be desirable to use the G.711 CODEC in a LAN environment, but switch to G.729 in a WAN
access connection. In the MITEL SX-200 IP NODE the switch of CODEC can be configured through The SX-200 CDE
form 23 Route Definition “Show IP” Compression Y/N’. Or in the case of a remote Set by Class of...

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When a WAN link is shared with other data devices there are other considerations including the introduction of waiting
delay. The end device sees this as jitter resulting in potential packet loss and the user experiencing voice quality
degradation. All these need to be considered.
3.7 Serialisation Delay
Serialisation delay is due to the fact that data is queued in a particular device, but cannot be sent because another packet
is currently being sent. In a fast link, such as in the LAN, this delay is...

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For slower speed links then the recommendation is to reduce the MTU in the routers/gateways to provide more
opportunity for the voice traffic. A value of 500 has been found to work well.
3.8 Network Priority
There are two areas where priority mechanisms operate in the network to ensure that voice traffic maintains high priority.
These are:
•  Layer 2 in the LAN through use of IEEE802.1p/Q
•  Layer 3 in the WAN through use of DiffServ/TOS/Precedence
The picture blow highlights an Ethernet packet...