What are the security implementations at each relevant layer of the OSI Reference Model?
• Layer 1 – (Physical Layer) All your network gear and servers are protected in secure, locked colocation facilities. • Layer 2 – (Data Link Layer) Extensive use of VLANs provides segregation of each customer’s traffic from AppNexus traffic and other customers’ traffic. • Layer 3 – (Network Layer) Bi-directional ACLs are applied on every routing interface with a Default Deny policy, meaning only explicitly permitted traffic is allowed to pass. • Layer 4 – (Transport Layer) The use of TCP-based protocols provides connection reliability and allows for session protection via ACLs and host firewalling. • Layer 7 – (Application Layer) There is extensive use of encryption (SSH, SSL-VPN) throughout the network.
