Design, implement, and support large-scale enterprise WAN/LAN networks. Responsibilities include routing/switching (OSPF/BGP), MPLS/VPLS, QoS, load balancing (F5/A10 with iRules), firewalls (Palo Alto/Checkpoint), network management and monitoring, capacity planning, upgrades, troubleshooting complex issues, vendor integration, documentation, mentoring, ITIL/change management, and occasional travel (up to 20%).