Extended Brain Storage

Encapsulation of Protocols

Posted on July 20, 2013

Encapsulation and bytes overhead of protocols related to ISO/OSI reference model...

Ethernet Overhead Calculation

Calculation of the Ethernet overhead:


Ethernet Frame Details

Calculation of the size of an Ethernet frame is equal to the sum of the size of its fields:

where:

Note: Technically, there is an IFG (12B) following the CRC32 field. Considering that IEEE 802.1Q is not used, the minimal size of the Data field within the Ethernet frame is 46B and the maximal size is 1500B.


Minimal and Maximal Possible Overhead

Minimal Ethernet protocol overhead occurs for maximal size of Data:

Maximal Ethernet protocol overhead occurs for minimal size of Data:


IPsec (in Tunnel Mode) Using UDP as Transport Protocol

                                 ------------------
064b (08B)                       | UDP |   Data   |
..........                  -----------------------
160b (20B)                  | IP |      Data      |
..........            -------------------------------------------
192b (24B)            | ESP |        Data         | ESP trailer |
..........       ------------------------------------------------
160b (20B)       | IP |           Data            |
.......... ------------------------------------------------
208b (26B) | Eth |              Data              | CRC32 |
.......... ------------------------------------------------
784b (98B) ... Total ...

IPsec (in Tunnel Mode) Using TCP as Transport Protocol

                                 ------------------
160b (20B)                       | TCP |   Data   |
..........                  -----------------------
160b (20B)                  | IP |      Data      |
..........            -------------------------------------------
192b (24B)            | ESP |        Data         | ESP trailer |
..........       ------------------------------------------------
160b (20B)       | IP |           Data            |
.......... ------------------------------------------------
208b (26B) | Eth |              Data              | CRC32 |
.......... ------------------------------------------------
880b (110B) ... Total ...

Tags: #TCP #UDP #ESP #IP #Ethernet #IPsec #encapsulation #security

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