Explain the function of the following network devices
Hub – Legacy device, not used in production environments today. However it operates at layer 1 of the OSI Model, multi-port repeater, operates a single collision domain. Everything is half duplex and becomes inefficient as speeds and loads increase.
Switch – Operated at layer 2 of the OSI model. Forwards traffic based on the MAC address. Every port on a switch is a dedicated collision domain.
Multi-Layer Switch – Some switches have routing capabilities and thus operate at both later 2 & 3 of the OSI model (router inside a switch)
Router – Operates at layer 3 of the OSI model, used to separate entire networks. Often connects diverse network types, such as LAN, WAN, Copper, Fiber.
Firewall – Operates at layer 4, selectively allows or blocks traffic based on the IP port number. Placed at the edge of the network and is designed to keep the bad guys out.
Content Filter – Designed to prevent users going to sites they shouldn’t. Can be used to help enforce an acceptable use policy, thus preventing users from accessing social media, sports and gaming sites.
Load Balancer – Distributes network traffic across multiple nodes which have all been configured the same. Can provide high availability and an improved performance for end users.
Wireless Access Point – Layer 2 device, not a wireless router. Acts as a bridge to the main wired network.
IDS – The Intrusion Detection System is a passive detector, quietly sits on the network and will raise alerts (email, text message, and pager) if a network attack is detected.
HIDS – Host based IDS can be installed on an individual computer or even a client PC.
IPS – The Intrusion Prevention System is active, if it detects any suspicious behavior on the network it may take action by shutting down ports and interfaces. Caution is required here, because a false positive could result in a denial of service for your users of the network.
Analog Modem – Uses a standard telephone line, works at 56K. Modulator / De-modulator
Packet Shaper – Control bandwidth usage, allow important applications to have a higher priority. Uses Quality of Service, QoS.
VPN Concentrator – The connection point for remote users, traffic is encrypted across the internet and decrypted on the internal private network.
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