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====== MAC Control Frame ======

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|desc=Introduce the ''MAC control frame'' in Ethernet.}}

===== MAC Control Frame Format =====

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<WRAP not>Table-1 MAC Control Frame Fileds</WRAP>

^ Field                      ^ Description                                                                                                                                                                                                                          ^
| Destination Address        | 48-bit address of the station(s) for which the frame is intended. It may be an **individual** or **multicast** (including broadcast) address.                                                                                        |
| Source Address             | 48-bit individual address of the station sending the frame.                                                                                                                                                                          |
| Length/Type                | Fixed to ''0x8808''.                                                                                                                                                                                                                 |
| MAC Control Opcode         | Indicate the MAC Control function. Some of the functions I have researched are listed [[#MAC Control Functions|here]].                                                                                                      |
| MAC Control Parameters     | MAC Control opcode-specific parameters. The length range of the MAC control parameter field is ''0'' to ''44''((note:>$64\ (minFrameSize) - 14\ (Ethernet Head) - 2\ (Opcode) - 4\ (FCS) = 44\ Bytes$)).  |
| Reserved                   | Fill with ''0'' to achieve 64 bytes ($minFrameSize$).                                                                                                                                                                              |

===== MAC Control Functions =====

<callout type="info">
Here is just a list of some of the functions I have researched. You can find the full opcodes assignments from <wrap doc>802.3-2022 <wrap clause>Annex 31A</wrap></wrap>.
</callout>

<WRAP not>Table-2 MAC Control Functions</WRAP>

^ Opcode(Hex)             ^ MAC Control function                    ^ Description                                                                                                                                                                   ^
| ''00-01''               | [[network:ethernet:macctrl:pause|PAUSE]]  | Requests that the recipient stops transmitting **non-control** frames for __a period of time__ indicated by the parameters of this function.                                  |
| ''01-01''               | [[network:ethernet:macctrl:pfc|PFC]]      | Requests that the recipient stops transmissions in the **priorities** indicated in the parameters of the function for __a period of time__ also indicated in the parameters.  |

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===== Further Reading =====

  * <wrap doc>802.3-2022</wrap>
    * <wrap clause>Chapter 31.4 - MAC Control frames</wrap>
    * <wrap clause>Annex 31A</wrap>