Cal Amp VIPER SC+ 100 series User Manual - page 62
Viper SC+™ IP Router for Licensed Spectrum PN 001-5008-000 Rev. C
| Page 52
Normally the random backoff should be set higher for systems that may have a lot of contention. Random backoff
can be disabled for systems that have a very controlled traffic pattern, where two or more Vipers are not expected
to try to transmit at the same time.
This parameter is often set equal to the estimated number of Vipers in the system that my try to start transmitting
at the same time.
When enabled this feature on average adds latency to each transmission. The latency will be noticeable when
conducting a standard Ping test, as the total Ping time will increase and be more variable in nature.
Valid settings for random backoff are values in the range of zero (off) to ten (0 to 10), inclusive. The default setting
is 2.
More Info — Clicking More Info displays the above information.
Additional Settings
TCP Proxy
The TCP Proxy setting is available only when the Viper is configured in Router Mode. The default setting is
Disabled.
The TCP proxy optimizes the throughput of a TCP connection by removing some of the TCP packets from the
airlink. A Viper receiving a TCP packet over the air sends an RF acknowledgement to the sending unit. If the
sending Viper receives the RF acknowledgement, it knows the packet made it across the airlink successfully.
When the TCP proxy is enabled and the TCP packet contained data, the sending Viper immediately generates a TCP
ACK to the sending host (RTU, PLC, PC, etc.). When the destination host receives the TCP packet, it generates a TCP
ACK back to the source. This TCP ACK is captured by the Viper and is not sent over the airlink.
Figure 34 – TCP Proxy
In this example, the following events occur in this order:
1) Host A sends a TCP data packet to Viper A.
2) Viper A transmits the packet over the air to Viper B.
3) Viper B immediately responds with an RF acknowledgement and sends the TCP data packet to Host B.