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Forum Topic - TCP RTO round up value configurable ? : (2 Items)
   
 
 
TCP RTO round up value configurable ?  
RFC2988 Section 2.4 states that the RTO should be rounded to a minimum of 1 second, whenever it is calculated to be 
faster than that. This also seems to be how the QNX stack behaves, we could never observe a RTO below 1 second (except 
for peer triggered TCP fast retransmissions)

In an embedded interconnect use case (with a single switch device between peers), where RTT is typically only a few 
milliseconds, the relatively long RTO seems to disturb data flow / throughput sometimes. 

Is it possible to configure the RTO round up value somewhere / somehow, in QNX 6.3.2 or 6.4 ? 

Thanks, 
Christopher 
Re: TCP RTO round up value configurable ?  
On Thu, Apr 10, 2008 at 10:10:10AM -0400, Christopher Pohl wrote:
> RFC2988 Section 2.4 states that the RTO should be rounded to a minimum of 1 second, whenever it is calculated to be 
faster than that. This also seems to be how the QNX stack behaves, we could never observe a RTO below 1 second (except 
for peer triggered TCP fast retransmissions)
> 
> In an embedded interconnect use case (with a single switch device between peers), where RTT is typically only a few 
milliseconds, the relatively long RTO seems to disturb data flow / throughput sometimes. 
> 
> Is it possible to configure the RTO round up value somewhere / somehow, in QNX 6.3.2 or 6.4 ? 
> 

Not currently.  It's a compile time option: TCPTV_MIN in
<netinet/tcp_timer.h>.

-seanb