LAN interconnection (LAN Switch)

LAN interconnection and layers

Repeater Simply regenerates electrical signals. So, all signals are propagated to all LAN segments. (no filtering) Repeater is called Ethernet hub.

Regenerating signal of repeater

Network configuration using hubs

Ethernet: sharing bandwidth All devices based on the Ethernet hubs share the whole bandwidth of the link (ex, 10Mbps). That is, a station can transmit with 10Mbps at any moment, but can not always transmit with this rate. Because of collision

Bridge A bridge can segregate the whole Ethernet network into several regions, reducing the number of stations to share the same link bandwidth. In the figure below, instead of 12 stations sharing 10Mbps, segregate into 4 regions, and only 3 stations in each region share 10Mbps.

Bridge (L2 switch) filtering When a bridge receives a frame, it transmits the frame only to the port where the destination station is connected, looking up the MAC address table..(filtering)

How to make the address table: self-learning Every time a bridge receives a new frame, it learns the location of new stations.

loop problem When a bridge makes the MAC address table, a loop can happen. So, Bridge should eliminate any loop, using the spanning tree algorithm. Actual network Reconfigured network using spanning tree

Switched Ethernet Ethernet switch is the same as the traditional bridge. The Ethernet switch have separate collision domains at each port like a bridge. So, each station at each port can be guaranteed to use the full bandwidth at any time.

Full Duplex Ethernet Original Ethernet is the half duplex. Full duplex Ethernet doubles the speed of the half duplex Ethernet.

Router (L3 Switch) A router determines which port a received frame(packet) should be transmitted based on the IP address. Compared to LAN switch(bridge), routers can segregate into even bigger regions, and can do much more functions.

LAN backbone Consists of many LAN segments. LAN backbone topologies Bus backbone Star backbone Ring backbone

Bus backbone

Star backbone

virtual LAN Compose LAN segments not by physical link configuration, but by software Single LAN segment consists of the same broadcast domain. 물리적 선로 연결에 의해서 세개의 그룹 ( 세그먼트 ) 로 구성되어 있다.

LAN segment configuration by virtual LAN Regardless of physical line configuration (ie, location of stations), LAN segments can be reconfigured as wanted.

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