Responsible for moving messages from one node to another until they reach the

Responsible for moving messages from one node to

This preview shows page 8 - 11 out of 40 pages.

Responsible for moving messages from one node to another until they reach the destination host Principal protocol is IP (Internet Protocol) o Adds its own Network layer message to the segment or datagram, and the entire Network Layer message is now called a packet o IP Address – an address assigned to each node on a network, which the Network Layer uses to uniquely identify each host o Relies on several routing protocols to find the best route for a packet to take to reach destination ICMP (Internet Control Message Protocol) and ARP (Address Resolution Protocol) o If the Network Layer Protocol is aware that a packet is larger than the maximum size for its network, it will divide the packet into smaller packets in a process called fragmentation
Image of page 8
Layer 2: Data Link Layer Layers 2 and 1 are responsible for interfacing with physical hardware on the local network o Protocols at these layers are programmed into firmware of a computer’s NIC and other hardware Type of networking hardware or technology used on a network determine the Link Layer Protocol used o Ethernet and Wi-Fi are examples Puts control information in a Link Layer header and at the end of the packet in a trailer Entire Link Layer is called a frame o The frame header contains the hardware addresses of the source and destination NICs. This is called the MAC (Media Access Control) address. o The physical addresses are short-range addresses that can only find nodes on the local network Layer 1: Physical Layer Simplest layer and is responsible for sending bits via a wired or wireless transmission Can be transmitted as: o Wavelengths in the air (Wi-Fi) o Voltage on a copper wire (Ethernet on a twister-pair cabling) o Light (fiber-optic cabling) Protocol Data Unit (PDU) The technical name for a group of bits as it moves from one layer to the next and from one LAN to the next o Technicians loosely call this group of bits a message or transmission
Image of page 9
Removing a header and a trailer form a lower layer’s PDU is called decapsulation Safety Procedures and Policies Fire Suppression System o Emergency Alert System – generate loud noise and flashing lights. Some send text and voice messages to key personnel, and post alerts by email, network messages, and other means o Portable fire extinguishers o Emergency power-off switch o Suppression agents – consist of a foaming chemical, gas, or water that sprays everywhere to put out the fire Fail Open or Fail Close o Does the security system allow access during a failure (fail open) or deny access during the failure (fail close)? o Example: during a fire alert, using a fail-open policy, all exit doors stay unlocked so that people can safely leave the building and firefighters can enter the building, even though it poses a security risk for thieves entering the building (fail open) o Example: if firewall software protecting access to a database of customer credit card numbers fail, it might be configured to fail close and to deny access to the database until
Image of page 10
Image of page 11

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture