On Sat, Apr 21, 2018 at 8:32 PM, [email protected] <[email protected]> wrote: > Hi Star, > what technology do you use for your long range links? Are there 3G > links with quite low signal quality and therefor you get a high loss > of packets? > > Please explain your setup so we can get a better overall picture of > what you are trying to accomplish.
Hi Valent, My setup is a full mesh VPN over UDP running on wired Ethernet. I use Babel to connect nodes all around the globe. The architecture includes 2 nodes located in US, 2 nodes located in Japan, 2 node located in China, and 2 nodes located in Germany. I want to have maximum TCP throughput between any of them. I found two problems: 1. A direct link Japan -> Germany takes 380ms RTT at peak hour, while Japan -> US -> Germany takes 260ms. I want Babel to choose an indirect link during peak hours. 2. The direct link between two China nodes has 10ms RTT but up to 20% UDP packet loss at peak hour, because some monopolic ISP punishes inter-ISP connections. I want packets to detour to Japan then back to China to reduce packet loss. The facts are: 1. Babel uses rxcost as 256 by default, so a 120ms difference does not add too much to the metric. I had to reduce rxcost to 16, but that leads to the next problem. 2. Link quality estimation scales by rxcost, not the sum of rxcost + RTT. Thus a high loss would contribute nothing to metric if rxcost is reduced. _______________________________________________ Babel-users mailing list [email protected] https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/babel-users
