Beef Stock

Combine all ingredients in large stock pot. Heat over medium heat to boiling; reduce heat. Simmer, uncovered, skimming occasionally, 6 hours. Strain stock through sieve lined with dampened cheesecloth; discard solids. Cool stock to room temperature; refrigerate, covered, until cold. Remove and discard fat from surface. Stock can be refrigerated up to 3 days or frozen up to 2 weeks; reheat to boiling before using.