Domain 4 - Communications & Network Security Flashcards
OSI Reference Model
Open System Interconnect Layers:
- Data Link
Describes network hardware such as electrical signals, network interfaces, and cables. Hubs and repeaters are at this level.
Data Link Layer
Describes data transfer between machines by Ethernet or other technologies like Token Ring. MAC (Media Access Control), LLC (Logical Link Control), switches and bridges are at this level.
Describes data transfer between networks by IPv4 or IPv6. IP Addresses and Routers are at this level.
Describes data transfer between applications, flow control and error detection and correction. TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are at this level.
Describes the handshake between applications like authentication processes.
Describes the presentation of information like ASCII, JPEG, GIF and TIFF. Data conversion, character sets and image formats are at this level.
Describes the structure, interpretation, and handling of information. In security terms, it is relevant because it relies on all the other layers.
Logical Link Control (LLC)
Manages connections between two peers. It provides error and flow control and control bit sequencing. Used in Layer 2 - Data Link.
Media Access Control (MAC)
Transmits and receives frames between peers. An Ethernet 48-bit hardware address is often referred to as a MAC address. Used in Layer 2 - Data Link.
Internet Protocol (IP)
The most important network layer protocol and has two functions:
Addressing - Destination IP addresses are used to transmit packets through networks until the packet’s destination is reached.
Fragmentation - IP will subdivide a packet if its size is greater than the maximum size allowed on a local network.
Routing Information Protocol (RIP)
A standard exchange of routing information among gateways and hosts. Uses distance vector algorithms to determine the direction and distance to any link in the internetwork. Hop count is the only routing metric used by RIP.
v1 allows a maximum hop count of 15 and allows updates at a programmable interval.
v2 adds cryptographic authentication and adds additional information.
Open Shortest Path First (OSPF)
An interior gateway routing protocol for IP based on shortest route first or link state algorithm.
Internet Control Message Protocol (ICMP)
ICMP's goals are to provide a means to send error messages from non-transient error conditions and to provide a way to probe the network in order to determine general characteristics about the network. Functions: 1. Announce Network Errors 2. Announce Network Congestion 3. Assist Troubleshooting 4. Announce Timeouts
Internet Group Management Protocol (IGMP)
Used to manage multicasting groups. There are three versions of this protocol that provide additional features.