R Ashby Armistead

Title: R Ashby Armistead: Innovator in Packet-Switched Telephony

Introduction

R Ashby Armistead is a notable inventor based in Los Altos, CA (US). He has made significant contributions to the field of telecommunications, holding a total of 13 patents. His work primarily focuses on enhancing the efficiency and reliability of packet-switched telephony systems.

Latest Patents

One of Armistead's latest patents is titled "Packet-switched telephony with circuit-switched backup." This invention discloses a packet voice switch and a method for its operation. The switch comprises a network switching means, preferably implemented within its host processor, that allows calls to be routed between a circuit-switched connection at a circuit-switched interface and either another circuit-switched connection or a packet-switched connection. The network switching means selects call routing based on a comparison of the current quality of service for the call over the packet-switched connection versus the extra cost of connecting the call over the circuit-switched connection. This comparison can be adjusted for call distance, the user's quality of service preference, and current system load. In a preferred embodiment, the switch communicates with a similar packet voice switch to initiate a mid-call network switch that is transparent to both calling and called parties. This provides a guaranteed minimum quality of service for packet voice applications and a reliable backup in case of a packet data route failure. Additionally, users may initiate network switching themselves for higher quality by entering a sequence on their DTMF keypad.

Another significant patent is "Intraserver tag-switched distributed packet processing for network access servers." This patent describes an access server architecture and methods to increase scalability and balance processor load for a network access server device. In this architecture, packet forwarding and processing are distributed among cards serving low-speed access lines. As the number of line cards expands, forwarding resources are increased proportionally. The architecture relieves the NAS route switch controller and high-speed ports from packet processing tasks, allowing for more efficient traffic management.

Career Highlights

Armistead is currently employed at Cisco Technology, Inc., a leading company in networking and telecommunications. His work at Cisco has allowed him to contribute to groundbreaking technologies that enhance communication systems worldwide.

Collaborations

Throughout his career, Armistead has collaborated with notable colleagues, including Robert L Sargent and Tod Walton Hays. These