From India, you could apply for Vietnam visa by two ways: First, directly at the Embassy/Consulate in India:
Embassy of Vietnam in New Delhi, India
Address: 17, Kautilya Marg, Chanakyapuri, New Delhi 110 021, INDIA
Phone: (91-11) 2301 98
Fax: (91-11) 2301 05
Office hours: Telephone: (00-91) 23018059 - ext: 46 (answering machine; visa officer available on phone from 4:00 to 5:00p.m or for emergency cases only)Working hours: 9:30am - 5:00pm, Monday through Friday. Applications are accepted in the morning, from 10:30 to 12:30.Visa collection is in the afternoon, from 4:00 to 5:00.
Consulate General of Vietnam in Mumbai, India
Address: B-306 Oberoi chamber New Link road andheri (w), Mumbai 400 053, India.
Phone: (9122) 2673 668
Fax: (9122) 2673 663
Office hours: Telephone: (00-91) 23018059 - ext: 46 (answering machine; visa officer available on phone from 4:00 to 5:00p.m or for emergency cases only) Working hours: 9:30am - 5:00pm, Monday through Friday. Applications are accepted in the morning, from 10:30 to 12:30. Visa collection is in the afternoon, from 4:00 to 5:00.
Or second, more easily, you could apply for Vietnam visa on arrival ' the visa picked up at arrival airport by applying online at the site govietnamvisa.com.This kind is used more and more today since it is simpler and cheaper. It is applicable for those travelling by air to Vietnam, and takes only 1 or 2 working days, and costs only US19.5$ for approval fee.