Hello All, I'd like to follow up on a post made in Feb 2010 ( http://mail.millennium.berkeley.edu/pipermail/tinyos-help/2010-February/044460.html ).
>From what I see in CtpRoutingEngineP.nc, CTP congestion control appears to be disabled via the ECNOff variable being hardcoded to "true," implying that nodes will never delay their transmissions or change their parent (with sufficient ETX delta) due to the parent's C-bit being set to 1. Am I correct? Also, could anyone provide any additional information regarding why congestion control is disabled (i.e., why ECNOff is hardcoded to "true")? Is this a design decision intended to offload congestion control to another layer, a section of code that requires more testing, or a feature that should be enabled only when an application can sacrifice latency for greater packet delivery? In some Castalia-based simulations of CTP, I tried enabling congestion control and did see a slightly more packets being delivered, with a tradeoff of increased latencies and THL (hop count). This seems reasonable to me -- packets could be delayed due to the congestion timer, and non-optimal routes might be temporarily selected while a parent is congested. However, I would appreciate any insights anyone has to offer on this. Thank you for your time and help! Jon Szymaniak
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