Communication system and communication apparatus controlling a switching hub for power saving

Abstract

A CPU of an image forming apparatus controls, according to establishment of a sleep change condition, a MAC/PHY in a network unit to change the image forming apparatus from a link-up state to a link-down state. The CPU controls the image forming apparatus to change from a normal mode to a deep sleep mode. A CPU of the network unit controls, according to the change of the image forming apparatus from the normal mode to the deep sleep mode, the MAC/PHY to change the link-down state of the image forming apparatus to the link-up state. The CPU controls the MAC/PHY to transmit a MAC address necessary for causing the image forming apparatus to participate in VLAN to a switching hub.

What is claimed is: 
     
         1 . A communication apparatus comprising:
 a communication unit configured to communicate with an external apparatus at any one of a plurality of communication speeds;   a processing unit configured to process data received via the communication unit from the external apparatus;   a changing unit configured to, in a case where there is an input of an instruction for returning the communication apparatus from a power saving mode, change the communication speed of the communication unit into a predetermined speed among at least one communication speed at which both the external apparatus and the communication apparatus are capable of performing communication; and   a control unit configured to control the communication unit so as to transmit identification information of the communication apparatus to the external apparatus in a case of a change in the communication speed of the communication unit into the predetermined speed by the changing unit.