|  | 7.5 | Effects of Layer 2 Devices on Data Flow
| 7.5.4 | Router segmentation of a collision domain
Routers are more advanced than typical bridges. A bridge is passive on the network and operates at the data link layer; whereas, a router operates at the network layer, and bases all of its forwarding decisions, between segments, on the Layer 3 protocol address. It accomplishes this by examining the destination address on the data packet, then looking in its routing table for forwarding instructions. Routers create the highest level of segmentation because of their ability to make exact determinations of where to send the data packet. Because routers perform more functions than bridges, they operate with a higher rate of latency. Routers must examine packets to determine the best path for forwarding them to their destinations. Unavoidably, this process takes time and introduces latency. Protocols that require an acknowledgment for every packet as it is delivered have a throughput of 30-40%. These are known as acknowledgment-oriented protocols. Protocols that require minimal acknowledgments, or sliding window protocols, suffer a 20-30% loss of throughput, due to the reduction of traffic between sender and receiver.