Home > General, linux > Firewalls, Switches, Routers and VPN – Provide High Speed Network Communication!

Firewalls, Switches, Routers and VPN – Provide High Speed Network Communication!

A switch is a hardware device that links the data where the Ethernet protocol works.  The switch is using the table to distinguish where to send all future frames that it receives. In technological term this tables is known as CAM table which is used for the bridge forwarding table. If a switch receives a frame with a destination then table floods that frame to all switch ports. It also put the Mac address in the table when it usually receives a frame. As we know switch is a high speed multiport bridge and most routers can also function as bridges.

The example of the SPI hardware firewall is the Cisco PIX firewall. It is the dedicated appliance as well as it looks like the Cisco router. The SPI firewall is stateful as it understands different states of TCP (the transmission control protocol). It knows what comes & what it goes & keeps the track of that all. Therefore, in case, the packet tried and come in however it was not requested, firewall knows that & drops that. Here is what we learned:

  • Routers work in Layer 3 & route IP packets between the networks.
  • Routers are been used to connect the LAN to WAN (like small network to Internet) however they will as well get used to connect the segments of large LAN, which is subnetted in the smaller segments.
  • Routers route the packets that are based on the information in IP routing table. You may see the table with show ip route command on the Cisco router.
  • Switches work in Layer 2 as well as switch Ethernet frames and switches connect the multiple devices on the local area network.
  • Switches keep the table of the Ethernet MAC addresses named the CAM Table or Bridge forwarding table. You may also see the table with show mac-address-table command at the Cisco switch.
  • Firewalls work in Layers 3 & 4 however some will work at the higher layers.


Categories: General, linux Tags:
  1. No comments yet.
  1. No trackbacks yet.