Echelon i.LON 600 LonWorks/IP Server - Manual (Page 70)

Section 2: Advanced Topics
Channel Timeout
Channel Timeout is the L ON W ORKS /IP channel property that assigns a delay for a packet
to travel across that channel. The assigned delay is a time parameter set in milliseconds
and 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 response. Synchronize the i.LON 600
routers with an SNTP time server.
Set the Channel Timeout parameter to a value in relation with the ping delay specified in
Table 12 . 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. Channel Delay is based on a
combination of bit rate, packet size, and media access. Generally, you should set Channel
Timeout on your L
ON W ORKS /IP channel to more than half the Channel Delay value.
Channel Timeout is highly recommended when using MD5 authentication. When using
MD5 authentication, set it to 100 MS and the Channel Delay to 200 MS.
Factors in determining Channel Timeout include:
• Variations on each leg of a round trip. Your timeout parameter should factor the
maximum delay into one leg of the trip.
• Maximum difference between the times on the L
ON W ORKS /IP devices. The
L ON W ORKS /IP device stamps its time on a packet when it is sent on the IP
network and the target L ON W ORKS /IP device compares the stamp to its own
time. If the time has expired, (time of device – time stamp in packet is greater
than channel timeout), the IP packet is discarded by the target device as stale.
You can estimate the maximum difference between the times on the devices by
comparing the offsets displayed in the Configuration Server log window log
when you run the channel Time Check command.
Packet Reorder Timer
Packet Reorder Timer is a L ON W ORKS /IP channel property that allows you to set the
amount of time that the device will wait for an out-of-order IP packet to arrive. This
parameter is important for wide area networks where IP packets can traverse multiple
routers from source to destination causing packets to appear on the receiver in a different
order than transmitted. If selected, the value defaults to 64 milliseconds.
Packets on a local area network do not get out-of-order, so you should not set the reorder
packets parameter in this case. Using the packet reordering feature or an overly long
reordering timer value can cause unnecessary delays in packet processing if a packet is
lost or corrupted. Whether enabled or disabled, out-of-order packets are never sent onto
the L
ON W ORKS network.
Channel Delay
Channel Delay is an LNS property that specifies the value of the expected round trip time
of a message (i.e. message and response). This allows expected traffic patterns to be input
to the system so that the timer calculations can be affected accordingly. This property can
be set using an LNS based tool such as LonMaker. See the LNS and LonMaker
documentation for more information on the Channel Delay property.
62 L ON W ORKS /IP Channel Parameters