1. Data is transmitted inside fixed period frames, each circuit is allocated a fixed subset of the time slots in each frame. Connection ID and routing information is provided implicitely by the timeslotID that a datum is transmitted in.

2. The transmission capacity of a link is partition into a fixed number of circuits, each of them havin a fixed rate; unused capacity in one circuit cannot be used by other circuits.

Pros: Simple.

Cons: wasteful in transmission capacity, especially when actual rate of connections varies widely with time.

Non-periodic multiplexing of packets, on a demand basis; each packet carries its own source and destination (connection) ID, and can be stored and forwarded at any later time.

Transmission capcity of a link is shared among all flows that pass through it, on a demand basis; any capacity that is not used by one flow can be used by another.

Pros: No waste of transmission capacity.

Cons: More complicated. Dynamic control (per packet), rather than status (at connection setup) is needed. Unpredictability of traffic, leading to contention for resources.

Open Systems Interconnection model (OSI model) (definition)

A prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar communication functions are grouped into logical layers. An instance of a layer provides services to its upper layer instances while receiving services from the layer below.

7. Application - All

6. Presentation - people

5. Session - seem

4. Transport - to

3. Network - need

2. Data Link - data

1. Physical - processing

Resonsible for User application services.

Data type: user data
Scope: application data

Examples: FTP; http; telnet; Simple Mail Transfer Protocol (SMTP)

Responsible for data translation; compresion and encryption.

Data type: encoded user data
Scope: application data representations.

Example: SSL; shells and redirectors; Multipurpose Internet Mail Extensions (MIME)

Session Establishment; management and termination.

Data type: sessions
Scope: sessions between local or remote devices.

Example: sockets; named pipes; remote procedure call (RPC)

Responsible for process-level addressing; multiplexing/demultiplexing; connections; segmentation and reassembly; acknowledgements and retransmissions; flow control.

Data type: datagrams/segments
Scope: communication between software processes.

Examples: TCP and User Datagram Protocol (UDP)

Logical addressing; routing; datagram encapsulation; fragmentation and reassembly; error handling and diagnostics.

Data type: datagrams/packets
Scope: message between local or remote devices.

Example: IP

Logical link control; media access control; data framing; addressing; error detection and handling; defining requirements of physical layer.

Data type: frames
Scope: low-level data messages between local devices.

Examples: IEEE standards; ethernet; Asynchronous Transfer Mode (ATM)

Encoding and signaling; physical data transmission; hardware specifications; topology and design.

Data type: bits

Scope: electrical or light signals sent between local devices.

Examples: Physical layers of techs listed under data link layer.

A communication service at an intermediate level between an application program and the Internet Protocol (IP). That is, when an application program desires to send a large chunk of data across the Internet using IP, instead of breaking the data into IP-sized pieces and issuing a series of IP requests, the software can issue a single request to this protocol and let it handle the IP details.

Note: It is optimized for accurate delivery rather than timely delivery.

1. Authentication Headers (AH)

2. Encapsulating Security Payloads (ESP)

3. Security Associations (SA)

Guarantees connectionless integrity and data origin authentication of IP packets. Further, it can optionally protect against replay attacks by using the sliding window technique and discarding old packets.

Note:  Operates directly on top of IP, using IP protocol number 51.

Provides origin authenticity, integrity, and confidentiality protection of packets. It also supports encryption-only and authentication-only configurations, but using encryption without authentication is strongly discouraged because it is insecure.

Note: Operates directly on top of IP, using IP protocol number 50.

Acts by inspecting the "packets" which transfer between computers on the Internet. If a packet matches the packet filter's set of rules, the packet filter will drop (silently discard) the packet, or reject it (discard it, and send "error responses" to the source). Note: Filters each packet based only on information contained in the packet itself most commonly using a combination of the following information:

1. Source

2. Destination

3. Protocol

4. Port

A network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network. Note:  They typically require remote users of the network to be authenticated, and often secure data with encryption technologies to prevent disclosure of private information to unauthorized parties.

Can be implemented via the Tunneling mode of Internet Protocol Security (IPSec).

1. Algorithms for detection of wireless energy

2. measurement of total signal power
appearing in small frequency sub-bands

3. algorithms to determine the geospatial
coordinates of the detected wireless device

User Datagram Protocol (UDP), so no concept of session, i.e., susceptible to flood attacks.

Note: Also, susceptible to eavesdropping,
reply, caller-id spoofing, and man-in-the
middle. Secured via isolation.

A file system that acts as a client for a remote file access protocol, providing access to files on a server.

- Host or storage device-based technology.

- Device sharing command usually allow permission at share level over and aboe file level.

Examples: UNIX Network File System (NFS); Windows File share; File Transfer Protocol (FTP)

A category of cloud computing services that provide a computing platform and a solution stack as a service.  Facilitates the deployment of applications without the cost and complexity of buying and managing the underlying hardware and software and provisioning hosting capabilities, providing all of the facilities required to support the complete life cycle of building and delivering web applications and services entirely available from the Internet. 

Offerings may include facilities for application design, application development, testing, deployment and hosting as well as application services such as team collaboration, web service integration and marshalling, database integration, security, scalability, storage, persistence, state management, application versioning, application instrumentation and developer community facilitation.

1. Availability.

2. Confidentiality.

3. Privacy and legal liability in the event of a security breach (as databases housing sensitive information will not be hosted offsite).

4. Data ownership.

5. concerns around e-discovery.

1. Who owns the applications?

2. Where do the applications reside?

1. Operated solely for an organization

2. May be managed by the organization or a third party.

3. May exist on-premise or off-premise.

1. Provides Cloud services with minimum risk.

2. May not provide the scalability and agility of public cloud services.

1. Shared by several organizations.

2. Supports a specific community that has a shared mission or interest.

3. May be managed by the organizations or a third party.

4. May reside on-premise or off-premiss.

1. Same as private cloud, plus:

2. Data may be stored with the data of competitors.

1. Made available to the general public or a large industry group.

2. Owned by an organization selling cloud services.

1. Same as community cloud, plus:

2. Data may be stored in unknown locations and may not be easily retrievable.

1. Aggregate risk of merging defferent deployment models.

2. Classification and labeling of data will be beneficial to the security manager to ensure that data are assigned to the correct cloud type.