Job Summary:
Operate, monitor, and maintain enterprise network infrastructure, including routing, switching, wireless, firewalls, and VPN connectivity. Troubleshoot incidents, support security audits, manage network changes and documentation, and contribute to infrastructure upgrades and automation.
Responsibilities:
Operations and Monitoring:
- Monitor the network infrastructure 24/7 via monitoring systems (Zabbix/PRTG, Graylog, Grafana) and handle alerts.
- Troubleshoot L1-L3 incidents: connectivity loss, latency, packet loss, loops/broadcast storms, asymmetric routing.
- Perform root cause analysis (RCA) and write incident reports for incidents affecting production.
- Take part in the on-call rotation.
Routing, Switching and Wireless:
- Configure and operate Cisco Catalyst, Nexus, and NetGear switches: VLAN, STP, EtherChannel/LACP, port security.
- Operate internal and inter-site routing: OSPF, BGP, static routing, DCI links between data centers.
- Manage the UniFi, Aruba WiFi system: coverage, roaming, channel optimization, SSID/VLAN mapping.
Security and VPN:
- Administer FortiGate and pfSense/NetGate: firewall policy, NAT, security profiles, HA.
- Deploy and operate IPSec site-to-site VPNs with customers and SSL/IKEv2 remote access VPN.
- Review firewall rules regularly: remove redundant/duplicate rules, apply least privilege.
- Work with the Security team on incidents and audits (ISO 27001).
Change Management and Documentation:
- Plan changes with impact analysis, rollback plan, and maintenance window.
- Keep network documentation current: topology diagrams, IP plan, runbooks, config backups.
- Manage firmware lifecycle and track device EoL/EoS.
Projects and Automation:
- Take part in infrastructure upgrade projects: device replacement, network redesign, added redundancy.
- Write automation scripts (Python, Ansible, REST API) for repetitive tasks such as config backup, audits, and bulk changes.
- Work with vendors/ISPs on escalation, RMA, and circuit deployment.
Requirements:
- Degree in IT, Electronics & Telecommunications, or related fields.
- 3+ years of experience operating enterprise networks (500+ users).
- Solid knowledge of TCP/IP, subnetting, VLANs, STP, OSPF, and basic BGP.
- Hands-on experience with FortiGate or equivalent NGFW (Palo Alto, Check Point).
- Proficient with Cisco IOS/IOS-XE and FortiOS CLI.
- Experience configuring and troubleshooting IPSec VPN (phase 1/2 mismatch, NAT-T, routing over tunnels).
- Proficient with Wireshark/tcpdump for packet analysis.
- Good English, communication, and interpersonal skills.
Preferred Qualifications:
- CCNA/CCNP, NSE4, JNCIA, or equivalent certification.
- Experience with Linux, Proxmox/VMware, and Windows Server networking (DNS, DHCP, AD).
- Python/Ansible skills, REST API experience, and tools such as n8n.
- Experience with MikroTik, UniFi, Aruba, pfSense.
- Experience with ISO 27001 or security audits.
Experience: 3+ years operating enterprise networks with 500+ users
Benefits/ Opportunity:
- Working in an international, dynamic and professional environment with many opportunities to develop career
- Having opportunities of being trained oversea and working directly with oversea customer
- A stable and rewarding position where your long-term commitment will be highly valued
- Technical & Soft skills internal training courses
- Many company activities (Sport and music festival, TMA Futsal league ...) are held annually
- Competitive salary and bonus
- Total Health Care Insurance
- Loan Fund
- Team Building Fund