skill test:
(1) required
one TIA568B straight-through cable

(2) optional (no extra points)
one cross-over cable

R1 ---- R2 ---- R3 ---- R4
 00    01 00   01 00   01 00

R1 ---- sw14 ---- R4

R1 01: 10.10.14.1/24
R1 00: 10.10.12.1/24
R1 lo0: 1.1.1.1/32
PC 3Com: 10.10.14.11/24

R2 01: 10.10.12.2/24
R2 00: 10.10.23.2/24
R2 lo0: 2.2.2.2/24
PC 3Com: 10.10.14.12/24

R3 01: 10.10.23.3/24
R3 00: 10.10.34.3/24
R3 lo0: 3.3.3.3/32
PC 3Com: 10.10.14.13/24

R4 01: 10.10.34.4/24
R4 00: 10.10.14.4/24
R4 lo0: 4.4.4.4/32
PC 3Com: 10.10.14.14/24