Layer 4+ refers to the Internet layers 4 and above (transport and application layers)
The term Layer 4+ refers to the Internet layers 4 and above, which are more closely related to customers/subscribers’ applications and the way they use Ethernet, the Internet, and perceive performance or quality.
Here is a summary of the seven layers defined by the Open Systems Interconnection (OSI) Model for communication systems, applied to Ethernet and Internet links
- Layer 7 – Application Layer (e.g., Telnet, FTP, HTTP, HTTPS, POP, SMTP, DNS, etc.)
- Layer 6 – Presentation Layer or Encoding/Encryption (e.g., MIME, SSL/TLS, etc.)
- Layer 4 – Transport Layer or TCP/UDP Layer (manages and terminates connections between local and remote applications)
- Layer 3 – Network Layer or IP Layer (uses IP addresses for data routing and forwarding between different networks)
- Layer 2 – Data Link Layer or MAC and LLC Layer (node to node data transfer)
- Layer 1 – Physical Layer (Electrical/Copper, Laser/Fiber, etc.)
The modern Internet is not directly based on the OSI model, but on a simpler TCP/IP model:
|
OSI Model |
TCP/IP Model |
|
7 - Application Layer |
Application Layer |
|
6 - Presentation Later |
|
|
5 - Session Layer |
|
|
4 - Transport Layer |
Transport Layer |
|
3 - Network Layer 3 |
Internet Layer |
|
2 - Data Link Layer |
Network Access Layer |
|
1 - Physical Layer |
Related Test Applications
With regards to VeEX test and measurement solutions, the following stateful test features are considered part of the Layer 4+ test suite:
- V-TEST Internet Access Speed Test (compatible with Ookla Speedtest™)
- V-PERF RFC6349-based Test (compatible with iPerf3)
- V-FTP FTP Upload and Download Performance Test