IP Network Packet & Voice Core Design Engineer (SC-Cleared/SC-Eligible)

IP Network Packet & Voice Core Design Engineer (SC-Cleared/SC-Eligible)

3 month contract/outside IR35

Travel to Newbury required as and when required.

Overview

Seeking an experienced engineer to design and implement end-to-end IP transport connectivity across Mobile Packet Core and Voice Core networks (EPC, 5G SA, IMS). The role involves producing HLD/LLDs, traffic flow designs, Firewall matrices, and leading implementation and fault-resolution activities.

Key Responsibilities

• Define IP connectivity requirements and traffic flows across Packet & Voice Core elements.
• Produce HLDs, LLDs, parameter assignments, and technical documentation.
• Present designs to Design, Operations, and Security teams.
• Create and review Firewall Communications Matrices.
• Develop MOPs and configuration scripts; implement changes out-of-hours.
• Lead troubleshooting and fault investigations for connectivity issues.

Required Skills & ExperienceMobile Core & Voice Core

• Deep knowledge of EPC & 5G SA protocols (DIAMETER, SIGTRAN, RADIUS, GTP, S1-U).
• Familiarity with nodes such as MME, PCRF, DRA, HSS, UPF, SMF, AMF, NRF.
• Strong understanding of Voice Core signalling (SIP, DIAMETER, SIGTRAN) and nodes (MTAS, SBC, CCSF, BGFs, HLR/HSS, UDF).

IP Networking

• Routing & switching: BGP, OSPF, MPLS, IPSEC, VXLAN, STP, LACP.
• Multi-vendor hardware:
  • Cisco (IOS-XR, NX-OS, ASR9K, Catalyst, Nexus)
  • Juniper (M/J/EX)
  • HPE 5k/12k
• Load balancers: F5 LTM/GTM, ACE, Netscaler
• Firewalls: Cisco ASA, Juniper SRX, Checkpoint, Palo Alto, Fortinet

Tools & Documentation

• Network analysis: Wireshark, TCPdump, Netscout, Gigamon, NetFlow, Tufin
• Strong experience producing HLDs, LLDs, implementation plans, UAT and support documentation.
• Ability to follow and enforce change management procedures