Shawn Lee
Mainframe Network System Programmer
Talent
Toronto, ONMember since June 30, 2026
Mainframe Network System ProgrammerSecurity: AT-TLS, IPSec for EE, IDS, Traffic Regulation, QoS, Firewall environmeExpert Trace Analysis (Wireshark, Sniffer, z/OS Packet Trace), Latency OptimizatMajor Communication Server application implementation and support: TN3270, FTP
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Mainframe Network System ProgrammerSecurity: AT-TLS, IPSec for EE, IDS, Traffic Regulation, QoS, Firewall environmeExpert Trace Analysis (Wireshark, Sniffer, z/OS Packet Trace), Latency OptimizatMajor Communication Server application implementation and support: TN3270, FTP
About
Highly accomplished Specialist with 30+ years of experience in mainframe TCP/IP, VTAM and enterprise-scale networking. Expert in implementing complex z/OS Communication Server features and optimizing data center infrastructures. Proven track record in resolving high-priority network bottlenecks through deep-dive packet analysis (Wireshark/Sniffer/Packet Trace) to ensure seamless, secure communication for Tier-1 financial institutions.
Experience
Senior z/OS Communication Server Specialist at Canada’s Largest Financial Institution | Toronto, ON | 2002 – Present
- z/OS Network Infrastructure: Led the support and implementation of z/OS Communication Server features including TCP/IP, VTAM, and Enterprise Extender (EE) for a global banking environment.
- Security Implementation: Enhanced system integrity by deploying advanced z/OS security features, including AT-TLS, IPSec, and Intrusion Detection Services (IDS).
- Performance Engineering: Act as the Tier-3 escalation point for complex connectivity issues between z/OS, end-users, and external vendors, utilizing Wireshark and Sniffer to reduce MTTR (Mean Time to Repair).
- Disaster Recovery: Redesign and implementation of GDPS network(TCPIP & APPN) ensuring 24/7 high availability for mission-critical banking applications.
- Legacy Integration: Managed the transition and coexistence of SNA/APPN and IP-based protocols within a modern data center framework.
- Data Center Network Support | 2015 – 2018 (Concurrent with z/OS support)
- Managed and configured Cisco enterprise-grade routers and switches to support core data center infrastructure.
- Resolved cross-platform application performance issues for internal business units and third-party vendors.
- Provided nationwide L2 support for IBM network products, including 3745/3746 Communication Controllers.
- Led network implementations for Fortune Global 500 clients, including Samsung, LG, and Hyundai.
- Developed and delivered technical training programs for field engineers.
- Provided hardware support for mainframe CPUs, storage (DASD), and massive transaction systems for major accounts such as Korean Air Lines & LG-EDS.
Education
Bachelor of Electrical Engineering | Korea University, 1989
Skills
Mainframe Network System Programmer
