Overland from Laos to Vietnam

Donsavanh (or Lao Bao)

Connects Sepon (Laos) and Dong Ha (Quang Tri, Vietnam), followed Highway No.9.
Tourist buses Savannakhet - Hue depart daily at 10pm, serving Dong Ha (US$7 per person, 329km), Hue (US$9 per person, 409km) or Danang (US$11 per person, 508km). Coming in the other direction, buses at Hue depart at 6am or 6pm daily, cost US$15 per person and take 13 hours. Shop around Savannakhet or Hue for good deals.
Alternatively, take local buses from Savannakhet (US$3 per person, 255km, 5 hours, leave at 7am and noon) or Sawngthaew (pick-up truck - US$3 per person, 210km, 4 hours, leave regularly) to Sepon, spend a night there before the next morning bus to the border. Across the border on foot, then continue 20-minute walking or take xe om (renting motorbike with driver - VND10,000 per person) to Lao Bao Bus station for departing Hue or Danang.

Nam Phao (or Cau Treo)

Near Lak Sao (30km east - Laos), Tha Kaek (200km - Laos) and Ha Tinh (Vietnam), Vinh (96km - Nghe An, Vietnam), followed Kaew Neua Pass (734m) and Highway No.8.
Daily bus Vientiane - Hanoi takes about 24 hours, and costs US$20-25 per person, depended on your bargain skills and where to buy (backpacker streets in Vientiane or Hanoi).
Alternatively, take local buses to Lak Sao, and sawngthaew (US$1 per person, 45 minutes, leave regularly) to the border, then looking for transportation to Vinh (US$15-25 per person).

Nam Can

Near Phonsavan (80km west - Laos) and Vinh (200km northwest), the most remote crossing - an endurance test and a half.
From Phonsavan, take local buses (20,000k per person, 4 hours, leave severally) or charter a private car (US$30) to Nong Haet. Catch any local transports to the border with about 5,000k per person. On Vietnamese side, grab xe om to Muang Xen (VND50,000 per person) then wait for bus to Vinh (US$2 per person, 7 hours, and leaves when full).

Tay Trang

Near Luang Prabang (Laos) and Dien Bien Phu (Dien Bien, Vietnam), followed Highway No.279. It’s newly opened up for tourists. We will keep updated on its news.

Please be noted that at some remote border crossings, you will find hassles in renting vehicles to get from point to point. Daily buses Vientiane - Hanoi and Savannakhet - Hue seem the only comfortable service for tourists.

All's for your satisfaction !