The following is the default Tor network in shadow simulator:
Total BW of Guard flagged nodes=258.15 MB/S
Total BW of Middle nodes=23.69 MB/S
Total BW of Exit flagged nodes=13.23 MB/S
Total BW of Guard+Exit flagged nodes=213.4 MB/S
I inserted 40 guard nodes and 40 exit nodes, each of 5 MB/S in above Tor network and performed the simulation.
Following are the bandwidth weights derived from the consensus document when Guard and Exit nodes of 5MB/S are added separately:
Wbd=1454 Wbe=0 Wbg=4882 Wbm=10000 Wdb=10000 Web=10000 Wed=7091 Wee=10000 Weg=7091 Wem=10000 Wgb=10000 Wgd=1454 Wgg=5118 Wgm=5118 Wmb=10000 Wmd=1454 Wme=0 Wmg=4882 Wmm=10000
Next I added 80 Guard-Exit (EE) nodes, each 5MB/S and perform the simulation.
Following are the bandwidth weights derived from the consensus document when EE nodes of 5MB/S are added:
Wbd=4722 Wbe=0 Wbg=0 Wbm=10000 Wdb=10000 Web=10000 Wed=4826 Wee=10000 Weg=4826 Wem=10000 Wgb=10000 Wgd=452 Wgg=10000 Wgm=10000 Wmb=10000 Wmd=4722 Wme=0 Wmg=0 Wmm=10000
I calculated the catch probability (probability that a client chooses my added nodes in guard as well as exit position while making circuit) in both cases and found that the second case yields more probability.
Why is the catch probability for EE nodes much higher than for guard and exit node separately? OR is there any other reason for this?