u := 1.25cm;
r := 3pt;

beginfig(1);
z1=(0,0);
z6=z1+u/sqrt2*dir90;
z2=z1+u*dir45;
z3=z1+u*dir-45;
z4=z2+u*dir-45;
z5=z3+u*dir-45;
drawarrow z1+r*dir angle(z2-z1)--z2+r*dir angle(z1-z2);
drawarrow z1+r*dir angle(z3-z1)--z3+r*dir angle(z1-z3);
drawarrow z3+r*dir angle(z2-z3)--z2+r*dir angle(z3-z2);
drawarrow z2+r*dir angle(z4-z2)--z4+r*dir angle(z2-z4);
drawarrow z3+r*dir angle(z5-z3)--z5+r*dir angle(z3-z5);
pickup pencircle scaled 2r;
for i=1 upto 6:  draw z[i];  endfor
label.lft(btex$T_1$etex, z1+r*dir180);
label.top(btex$T_2$etex, z2+r*dir90);
label.llft(btex$T_3$etex, z3+r*dir-135);
label.rt(btex$T_4$etex, z4+r*dir0);
label.lrt(btex$T_5$etex, z5+r*dir-45);
label.lft(btex$T_6$etex, z6+r*dir180);
endfig;

bye