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With network function deployed as physical appliances, being preintegrated bundles of hardware and software, new services require changing the physical structure of the network and this takes as long as months or even years and incurs the cost of a field workforce. While With Network Function Virualisation, there has been movement from appliances towards virtualisation to separate separation of hardware and software and enable a more open supplier ecosystem, this largely occurs with a single vendor's product set and there is no strong industry towards vendors deploying their software on each other’s hardware or opening of network infrastructure to client or third party innovations.
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