Operations Manual

OPERATIONS 4-36
O&M of the MCC-545B PACKET DATA RADIO
12/2000
RDOWN parameter gives the number of minutes to time out a Remote neighbor. Setting
NDOWN or RDOWN to “0” disables the feature (i.e., never declare neighbors down).
SNP,OTL Congestion control outstanding text limit
The OTL parameter specifies the maximum number of messages that will be transmitted while
waiting for ETEs. Limiting messages, as cars are limited to entering the freeway at rush hour,
tends to reduce congestion and memory buffer usage in the network and reduce the number of
retries that happen as a result. Sending messages one at a time does not take advantage of the
overlap caused by the ETE needing to come back through the network and does not take
advantage of an occasional large burst that can significantly improve throughput.
SNP,CONNP Priority for connectivity messages
SNP,ETEAP Priority for end-to-end-ack messages
SNP,FLOODP Priority level to initiate “flood-routing”
SNP,DATAP Priority for data reports
The priority of network control messages should be set higher than the data traffic. This setting
makes sense if you realize that messages can not get delivered as fast if the network connectivity
is incorrect. Certain applications may have reasons for altering these values but any revision to
the default priority scheme should be implemented carefully.
SNP,HTO History timeout for duplicate filtering
As each message is received by a unit, the originator ID and message serial number are retained
in a history table. The HTO parameter specifies how long to retain each entry. Each received
message ID is compared to this table and if the message was previously received and has not
timed out, it is considered a duplicate message. The ETE is sent to the originator if it is a text
message type but the duplicates are not output to the I/O ports. Duplicates happen due to
network connectivity changes and retries.
SNP,INF Infinity hop count
The INF parameter specifies the maximum width of a network in hops + 1. If this parameter is
set lower that the actual network width, units will be declared offline when they are not. If the
number is set too high, extra connectivity packets are exchanged when a unit goes offline and the
system looks for alternate routes.
SNP,MBHOP Meteor burst link hop weight
The MBHOP parameter defines the number of network hops to associate with a meteor burst
Master Station link when determining the minimum path to use in routing a message. This
parameter should be set high enough to prevent a meteor burst Master Station link to be picked
over a line-of-sight Remote to Remote link in a generally line-of-sight network.