A network architecture for implementation in a vehicle, said network architecture characterised by: an Ethernet gateway module, EGM, comprising an Ethernet switch and router therein, said EGM configured to provide an open data network, ODN, connection to said network architecture for a plurality of open data network devices; and network interface module, NIM, configured to provide an isolated data network, said NIM comprising: an Ethernet switch to connect a plurality of secure devices to an isolated data network, IDN, the secure devices related to operation and navigation of the vehicle; a router configured to interface the IDN to the open data network connections, said router comprising a packet filtering function to determine which, if any, data from the ODN may be passed through to the IDN and applied to operation and navigation of the vehicle via the secure devices connected to the IDN; a gateway/router providing network address and protocol translation to connect the IDN to a secure common data network, CDN, associated with vehicle operation, said architecture providing segregation between network devices in the IDN and CDN related to operation and navigation of the vehicle, and network devices in the ODN; and a controller service module, said controller service module configured to provide network management services to the ODN and to provide fault reporting across the IDN, wherein the IDN is configured to provide the fault reports to the CDN, the CDN configured to host an aircraft maintenance system. an Ethernet gateway module, EGM, comprising an Ethernet switch and router therein, said EGM configured to provide an open data network, ODN, connection to said network architecture for a plurality of open data network devices; and network interface module, NIM, configured to provide an isolated data network, said NIM comprising: an Ethernet switch to connect a plurality of secure devices to an isolated data network, IDN, the secure devices related to operation and navigation of the vehicle; a router configured to interface the IDN to the open data network connections, said router comprising a packet filtering function to determine which, if any, data from the ODN may be passed through to the IDN and applied to operation and navigation of the vehicle via the secure devices connected to the IDN; a gateway/router providing network address and protocol translation to connect the IDN to a secure common data network, CDN, associated with vehicle operation, said architecture providing segregation between network devices in the IDN and CDN related to operation and navigation of the vehicle, and network devices in the ODN; and a controller service module, said controller service module configured to provide network management services to the ODN and to provide fault reporting across the IDN, wherein the IDN is configured to provide the fault reports to the CDN, the CDN configured to host an aircraft maintenance system. an Ethernet switch to connect a plurality of secure devices to an isolated data network, IDN, the secure devices related to operation and navigation of the vehicle; a router configured to interface the IDN to the open data network connections, said router comprising a packet filtering function to determine which, if any, data from the ODN may be passed through to the IDN and applied to operation and navigation of the vehicle via the secure devices connected to the IDN; a gateway/router providing network address and protocol translation to connect the IDN to a secure common data network, CDN, associated with vehicle operation, said architecture providing segregation between network devices in the IDN and CDN related to operation and navigation of the vehicle, and network devices in the ODN; and a controller service module, said controller service module configured to provide network management services to the ODN and to provide fault reporting across the IDN, wherein the IDN is configured to provide the fault reports to the CDN, the CDN configured to host an aircraft maintenance system.