Instruct: Classify a given Amazon review into positive or negative sentiment.
Query: An Excellent Frame Relay Reference !

"Frame Relay: Technology and Practice" is an excellent resource for network managers, designers, engineers, & support staff. Jeff Buckwalter provides valuable insights into frame relay technology fundamentals, network design, and evaluating frame relay service providers. The concepts presented improve the reader's ability to design, implement, and support a frame relay networking infrastructure.