BANDING - There is a lot of confusion in regards to banding. Part of the confusion is because the term Agouti is used both to describe a series of genes, the "A" genes, and also because it is sometimes used as a colour name. Just because a coat is banded does not necessarily make it Agouti.
Agouti (as a colour) is banding of dark coat (eumelanin) and light coat (phaeomelanin). See Figure 1 on the left below. This photo is a close up of wild rabbit fur. The coat changes are quite abrupt as it changes from dark to light in the same hair shaft. Though the photo appears circular, the wild patterning is not a circular pattern. This photo was taken when blowing on the coat to show the band layers right down to the skin. Other coats can be banded as well.
Both Sables and brindles often have bandings in the light areas of their coats. These will be shaded bandings, with the bands growing in many shaded of the same colour, so there can be bands of gold, champagne, caramel, cream etc. Those are all clear shadings (phaeomelanin) - see figure 2 below in the center. Similarly dark coats can also be banded, especially in dark and light silvers. In these, the dark coat is banded in shades of dark coat only (eumelanin). So the banding can be black, charcoal, silver, etc... all shades of dark coat colours. Remember that the lightest shades of silver can be very pale and can easily be confused with being a light/clear colour. - see figure 3 below on the right. The banded shadings may be caused by input of the wild gene though this is not certain. Agouti as a colour is also not the same as sable. Sable coats only have the dark at the tips or ends of the coat, or as individual dark hairs. The dark coat is not banded into the rest of the coat.