Which two functions describe the TCP optimization feature in Cisco SD-WAN?

TCP optimization in Cisco SD-WAN aims to improve application performance over lossy or high-latency WAN links. One key function is the use of TCP Selective Acknowledgment (SACK). SACK allows the receiver to inform the sender about all segments that have been successfully received, not just the last contiguous segment. This helps the sender retransmit only the missing segments, improving efficiency compared to traditional cumulative acknowledgments. Another crucial function is terminating TCP connections locally at the WAN edge. This creates two separate TCP sessions: one between the client and the local WAN edge device, and another between the local WAN edge and the remote WAN edge device. This isolation shields the end-to-end connection from WAN impairments like latency and packet loss, allowing the WAN edge devices to optimize the WAN segment independently. While TCP ACKs are fundamental to TCP, SACK is the specific enhancement used for optimization. Terminating connections at the remote WAN edge is part of the overall process but not a function describing the optimization feature itself, which involves the local termination. TCP optimization primarily addresses data plane traffic, not control traffic.