| OSI
reference model |
|
|
|
| A (protocol
residing in a) lower |
||
| layer provides certain
services |
||
| to a (protocol
in a) higher layer |
||
| 7. Application |
| 6. Presentation |
|
|
| Protocol Data |
|
| Units (PDU) |
|
| 5. Session |
| 4. Transport |
| Headers |
| 3. Network |
| 2. Data Link |
| 1. Physical |