The question doesn't work becaues the scale (and terrain) does not come close to matching.
1. 'Dien Bien Phu (DBP)' was an isolated french base in a remote part of the country, limiting their chance of reinforcement from the beginning.
The Green Zone is in the heart of Baghdad, in the center of Iraq, there are a number of HUGE military bases within 20 miles of the Green Zone, a few minutes' flying time. Heck,if things got bad, they could get help from the Tigris River Which flows right next to it!!
2. DBP was situated in a valley, and the Viet Minh got on the high ground (Ho Chi Minh described it as 'a rice bowl' with the French at the bottom) pounding the base to pieces.
Most of Iraq, to include Baghdad, is flat as a pan. No high ground to speak of.
3. DBP was an interim base, an airstrip and basic fortifications.
The GZ was buit by Saddam, designed from the ground up to be defended in case of revolution, protected by reinforced walls and built-in bunkers.
4. The fact is, the reason the the insurgency started using IED's was every time they came in the open to attack, they got hammered.
In the end the GZ only too small a target for that kind of exposure, and to lay seige to one of the other bases in the area, they would be in the open, unlike the jungle cover used by the Viet Minh.
Myself, 18 months Iraq (near the Green Zone)