Echelon IP-852 Channel - Manual (Page 34)

26 IP-852 Channel Parameters
All authentication keys within a single network must match. Verify that you have
previously entered the same authentication key on all the IP-852 devices defined on this
channel
To disable authentication on a channel that has authentication enabled, clear the
Authenticate check box and click Apply.
IP-852 Channel Timing Considerations
When designing an IP-852 channel over an IP network that might have a large latency,
such as the Internet, you may need to adjust three timing parameters when configuring
the channel. You ca set two of the timing parameters, Channel Timeout and Reorder
Packets, using the IP-852 Configuration Server. You can set the Channel Delay using an
application network management tool such as the LonMaker tool.
On local area networks, set a Channel Timeout if MD5 Authentication is used, disable
Reorder Packets, and set the Channel Delay for the channel to twice the aggregation
timer.
On networks using the Internet, set the Channel Timeout and Reorder Packets
values to be consistent with the Channel Delay parameter. Table 3.2 specifies how to
approximate the timing values for network implementations using the Internet.
Table 3.2 Timing Parameter Calculations for Internet IP-852 Channels
Timing Parameter Set to:
Channel Timeout (Average Ping Delay / 2) + 20%. A typical LAN based
channel will require at least a 50 ms delay and a typical
WAN based channel will require at least a 100 ms delay.
Packet Reorder Timer The lesser of the following two values: ¼ of Channel
Timeout Value, or 64 MS
LonMaker Channel
Delay Average Ping Delay + 10%
If you are using aggregation and the aggregation delay is a high percentage of the
channel timeout or channel delay, add twice the aggregation delay to the Channel
Delay property and one times the aggregation delay to the Channel Timeout property.
Use the ping command from a Command Prompt to obtain the average ping delay.
Channel Timeout
The channel timeout property sets the delay for a packet to travel across a channel. The
assigned delay is a time parameter set in milliseconds that indicates how old a packet
can be before it is discarded. If you are sending packets across a virtual private network
or any configuration that uses the Internet, set the Channel Timeout parameter to ½ the
average ping delay. Synchronize the IP-852 device routers with an SNTP time server.
Set the channel timeout parameter to a value in relation with the ping delay specified in
Table 3.2. In a L
ON W ORKS network, each channel is assigned a cost defined as the round
trip delay for a packet traveling across that channel. The channel delay is based on a
combination of bit rate, packet size, and media access. Generally, you should set the
channel timeout on your IP-852 channel to more than half the channel delay value.