Normal problem while plot in GL_QUAD_STRIP

I am doing some code about millions of polygon. To improve frame rate, I have to organize the quad set into a piceces of quad strips. it is really to decrease the time cost while moving camera.

While in shading mode, I find there are a piece of discontinus bands in the joints between strips. I guess it was caused by discontinuous normals. But if I plot the quad in GL_QUADS, it is no problem at all.

Could anybody give me any suggestion and hints?

Thanks a lot.

you’ve probably got something freaky in your strip indexes. i would go over my strip index code again.