Echelon LonWorks Router - Manual (Page 27)

App
lication Buffer Out Priority
1 42 42
Network Buffer Out Priority 3 66 198
Total Allocated Bytes 1343
Unused 1 65 65
Total Available Bytes for Transaction
Records and Buffers
1408
Total Available Bytes for Buffers,
including Default Transaction
Records shown in first two lines,
above
1313
You will not have a problem interchanging routers with Router Firmware
Versions A, B, or C if you are not changing the router buffer or transaction record
configuration. If you need to change the configuration, make sure that the total
number of bytes required for the buffers and transaction records does not exceed
the capacity for the version of the router firmware that you are using. For
example, to use the OpenLNS Commissioning Tool or the LonMaker Turbo
Integration Tool to safely change the buffer configuration for a router, right-click
the router shape in the OpenLNS CT or LonMaker drawing and then click
Properties on the shortcut menu. Click the Buffers tab to display and change
the buffer configuration. As you change the buffer configuration, the required
memory for each side of the router for your buffer configuration is displayed
under the Memory heading. Verify that the memory required is less than the
buffer capacity listed in Table 3 or Table 4 (as appropriate for your router
firmware version) before clicking OK or Apply. When you click OK or Apply,
the buffer configuration you selected is written to the router if you are attached
to the network and you are OnNet. If the memory required is larger than the
buffer and transaction record capacity, the router will fail to operate.
In applications that must route large explicit messages with more than 40 bytes
of data, the buffer size must be increased, and the count of nonpriority buffers
decreased. See the Neuron C Programmer’s Guide to understand how the
network buffer sizes are calculated. See Network Management Messages in this
guide for a description of how to change the size and count of buffers. You can
also use the NodeUtil Node Utility, which you can download from the Echelon
Web site. However you allocate the transaction record counts and the buffer
sizes and counts, the total memory required by the transaction records and buffer
must not exceed the total available memory size in Table 3 or Table 4 (as
appropriate for your router firmware version) .
The default buffer configuration places the bulk of the buffers on the output
queues of the router. The reasoning behind this configuration is to keep buffered
packets on the output queues, after they have been processed for forwarding.
This processing includes checking for priority packets. Priority packets are
sensed and forwarded through the router’s priority output buffers, so that
priority packets are processed as quickly as possible, rather than allowing them
to be delayed behind non-priority packages in a large input queue.
There are applications, however, where the network traffic can be “bursty”,
where many packets appear on the network almost at the same time. In these
cases, the traffic bursts could cause the input queue to become full and lose
excess packets.
L ON W ORKS Router User’s Guide 17