'We have had a numberof customers that have come to us asking when do they need to change the LAN setting or thejitter buffer settings on your product to improve connectivity issues'.   There are far toomany variables when going over IP networks to allow us what state what the bestsetup would be depending on the network topology. With regard to AoIPproducts the decision is in the ‘ear of the beholder’, and by that we mean if theusers are experiencing choppy audio (i.e. packet loss). Packet loss can occuranywhere within the network and therefore, several countermeasures can beapplied to limit the amount of packet loss depending on the root cause: A)JitterJitteris a behavior where the speed at which packets are received over the networkvaries due to a variety of possible QoS issues.  Without a jitter buffer,any packet received later than expected would be dropped by the targetdevice.  The user would observe the dropped packet as silence but due tothe high frequency of packet transmission, a few dropped packets would soundlike choppy audio as the dropped packets would in essence create holes withinthe audio stream. To address this, Jitter buffers have been implemented tobuffer the received packets for a certain duration before the audio is playedback to the user. This buffering prevents dropping of packets that are receivedlater than expected or even packets received out of order.  The result isa cleaner sounding audio experience but at a cost.  The minimum buffersize selected has a direct impact on latency.  The lowest selectablejitter buffer setting is 5ms – 60ms. If a 20ms – 60ms jitter buffer isselected, then latency observed by the listener will be increased by at least15ms. One more thing to note is that the jitter buffer implementation inClear-Com products is dynamic.  This means that if jitter is observed bythe unit to be higher than the minimum buffer size (20ms in this example), thenthe buffer will dynamically increase or decrease to account for the variancebut only up to the maximum size specified (60ms in this example). Therefore, with this 20ms – 60ms setting, if a packet is received more than60ms late, then that packet will be dropped and choppy audio will be observeduntil the buffer is once again increased to handle the excess jitter. Dependingon the product, the jitter buffer can be modified either manually or bydecreasing the overall network quality setting.  B)Audio BitrateTheAudio Bitrate setting defines the level of information captured for each audiosample.  The higher the setting the bigger the packet will be resulting ina higher network bandwidth utilization.  If a high Audio Bitrate isselected while utilizing a low bandwidth network, packet loss would be thelikely outcome once again resulting in the observance of choppy audio. Therefore, it is recommended to decrease the Audio Bitrate when operatingwithin a low bandwidth environment.  Depending on the product, the AudioBitrate can be modified either manually or by decreasing the overall networkquality setting. C)Packet SizePacketSize, or sometimes referred to as Frame Duration, defines the amount of audioinformation, measured in milliseconds, that each packet contains.  So aPacket Size setting of 5ms will result in each packets being transmitted tocontain 5ms worth of audio.  It is important to also understand thatpacket size and network bandwidth have an inverse relationship. The reason forthis is that each packet is constructed with both a header and a payload. Thepacket header is always the same size and contains routing and otherinformation to ensure proper packet delivery. The payload portion of the packetcontains the audio data.  Reducing the Packet size just reduced thepayload and not the header which ultimately results in a higher overhead perpacket transmitted as.  Sending a payload that is 10x larger than theheader is much more efficient that sending a payload that is only 5xlarger.  Depending on the product, the packet size can be modified eithermanually or by decreasing the overall network quality setting. D)Forward Error Correction (FEC)Incertain products, FEC has been implemented to provide a method for packetreconstruction on the receiving end.  The concept is that each packettransmitted contains information about previous packets which can be used toreconstruct a lost packet when required.  Normally, enabling this featurewill increase the amount of information contained within each packet but withsome network quality settings, the bitrate is lowered to counter the increaseddata ultimately resulting in a wash.  Note that in order to fill packetsready for transmit with prior packet information, the transmit mechanism mustwait for the duration of the previous packet’s duration before sending. This ultimately results in an increased latency originating at the sender by afactor equal to the amount of the FEC level specified. If the NetworkQuality adjustments stated above resolve the issues being experienced but withtoo great a cost on audio quality and/or latency, then addressing limitationsof the Network infrastructure will need to be addressed with your ITprofessional or Internet Service Provider (ISP).Clear-Com can onlyprovide the tools to counter poor network quality environments which ourequipment may be operating within. That said, effort has still been invested inmaking these tools simple to use as possible through the abstraction oflabelled configuration sets which attempt to coalesce the best combination ofsettings for a given environment which can then be selected within the userinterface.Clear-Com recommendsthe use of the highest network quality setting possible so long as clean audiois observed.  Therefore, begin testing with the highest network qualitysetting and only lower it if anomalies are observed.Note thatthe law of the lowest common denominator directly applies to network transportand as a result, any limitation between two endpoints will directly affect thetransmission as a whole including bandwidth limitations. For example, having a1 Gb/s link on your local LAN segment but only a 10Mb/s link between routers orgateway devices will result in an overall throughput of no greater than 10Mb/s.