Pursuant to the authority of the State under the Twenty-First Amendment to the United States Constitution and to promote the public’s interest in fair and efficient distribution of beer, ale, porter, and other similar malt or fermented beverages, and to ensure the public’s interest in uniform and effective control of the distribution of these beverage products in the State, a wholesaler may sell any brand of these beverage products in this State only in the territory described in a distribution agreement filed pursuant to this article authorizing sale by the wholesaler of the brand in that designated area. Within that designated area, the wholesaler must service all holders of retail permits without discrimination. The distribution agreement must be in writing, must specify the brands it covers, and must be filed with the department. If a brewer sells more than one brand, the agreement need not apply to all brands sold by the brewer and may apply to only one brand. No brewer, importer, or other supplier may provide by a distribution agreement for the distribution of the brand filed pursuant to this article to more than one wholesaler for all or any part of the designated territory. However, a wholesaler may, upon approval of the department, service a territory outside the territory designated in its distribution agreement during periods of temporary service interruptions when requested by the brewer and the wholesaler whose service is temporarily interrupted.