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6.3 Describe the function of common networking components

Hub

  • not intelligent, does not route traffic, simply repeats it
  • every device receives every frame

Bridges

  • also not intelligent
  • connects 2 physical network segments that use the same protocol
  • builds a MAC address table of all devices that are connnected on its ports
  • if bridge is unable to find target address on the side it received traffic it forwards the traffic across the bridge, hoping it will be on other side

Switches

  • the intelligent Hub
  • analzyes traffic and builts a port-to-MAC address table
  • Layer 3 switches build a port-to-IP table and works at the network layer
Layer 2 Switch Layer 3 Switch

Operates at Layer 2 (data link) of the OSI

model

Operates at Layer 3 (network layer) of the OSI

model

Uses MAC addresses for forwarding Uses IP addresses for forwarding
Performs Layer 2 switching only Performs both Layer 2 and Layer 3 switching

Can be used to reduce traffic security on

the local network

Can be used to implement a virtual local-area

network (VLAN)

Has a single broadcast domain Has multiple broadcast domains

Routers

  • routers network traffic between networks where L3 switches operate within a single network
  • can optimize the best path with protocols sich as RIP, OSPF, and BGP
  • Functions:
    • Network segmentation: uses NAT to map private IP addresses to public
    • IP Address management: uses DHCP to assign IP addresses to devices that connect to network
    • Firewalls: blocks traffic from unauthorised users. Can block on specific ports such as HTTP or SSH etc
    • Domain name proxy: interacts with cloud DNS servers to resolve DNS queries. The queries/hosts can be stopped at the source if they are deemed harmful