161 Network Devices Surasak Sanguanpong nguanku ac th

/161 Network Devices Surasak Sanguanpong nguan@ku. ac. th http: //www. cpe. ku. ac. th/~nguan Last updated: 27 June 2002 Applied Network Research Group Department of Computer Engineering, Kasetsart University

/162 Functions v. s. OSI Model Application Presentation Session Transport Network Router Network Data Link Bridge Data Link Physical Repeater Physical Applied Network Research Group Department of Computer Engineering, Kasetsart University

/163 Hub/Repeater hub The frame is repeated out all the other ports A sends a frame to D A l l l D D D B C D D Attempt to forward all Frames Error Frames will be forwarded A hub regenerates signals; it does not an amplifier Applied Network Research Group Department of Computer Engineering, Kasetsart University

/164 Hub characteristics collision domain, broadcast domain hub A l hub B C D E F G Hubs create a single collision domain and a broadcast domain H All devices connected to hub: l l share the same collision domain share the same broadcast domain Applied Network Research Group Department of Computer Engineering, Kasetsart University

/165 Hub Model Application Presentation Session Transport Network Data Link Physical l Repeater Physical Deal with signaling : operate at the Physical Layer Applied Network Research Group Department of Computer Engineering, Kasetsart University

/166 Bridge operations Filtering segment 2 2 A to B C segment 1 A G 3 H 2 1 Forwarding 4 Station port A 1 B 1 C 2 D 2 E 3 G 4 l l The frame A-to-B is blocked 4 segment 4 D B 1 2 A to C 3 1 E The frame A-to-B is forwarded 4 to port 2 3 F Flooding segment 3 Forwarding Table )F and H is currently unknown( Selectively forwards frames Error Frames will not be forwarded Applied Network Research Group 2 A to F 1 The frame A-to-B is flooded 4 to all ports 3 Department of Computer Engineering, Kasetsart University

/167 Bridge characteristics collision domain A B bridge collision domain C D broadcast domain l l All devices connected to bridges share the same broadcast domain Networks are segmented; each segment is its own collision domain Applied Network Research Group Department of Computer Engineering, Kasetsart University

/168 Bridge Model l Application Presentation Session Transport Network Data Link Bridge Data Link Physical Repeater Physical Deal with Data Link Frame : operate at the Data Link Layer Applied Network Research Group Department of Computer Engineering, Kasetsart University

/169 Bridge operations 2 1 A B B bridge C A A-to-C A B C C bridge 1 B A B bridge B-to-A station port Station A transmits to Station C. The bridge starts building its bridging table and forward the packet. A 1 station port D-to-A A D 2 1 Initially, the bridge’s table is empty D 2 1 A C bridge station port D A D 1 2 Station D transmits to Station A. The bridge forward the packet and continues building its table. A D 2 station port C Applied Network Research Group D A D B 1 2 1 Station B transmits to Station A, the bridge does not forward the frame, since A also resides on port 1 Department of Computer Engineering, Kasetsart University

/1610 Loop in Bridge Packet is infinite looping! l The learning bridge concept works for any tree (loop free) topology Applied Network Research Group Department of Computer Engineering, Kasetsart University

/1611 Loop Avoidance with algorithm Spanning-tree algorithms disable some interfaces to break the loop Applied Network Research Group Department of Computer Engineering, Kasetsart University

/1612 Type of bridge l Transparent Bridges l l Translational Bridges l l l Same Topologies Converts frame types from one topology to another For example, Ethernet to FDDI Source Route Bridges l l Token Ring Only IBM Legacy Applied Network Research Group Department of Computer Engineering, Kasetsart University

/1614 Router l l Network is partitioned in to a small subnetwork Each node has its own l l Data Link Layer address (e. g. Ethernet MAC address( Network Layer address (e. g. IP Address( network 1 network 2 network node 1, 2, 3 1 3 1 2 1. 3 2. 2 1. 1 2. 3 2. 1 3. 1 No node inside Applied Network Research Group Department of Computer Engineering, Kasetsart University

/1615 Router characteristics broadcast domain collision domain l l l Collision domains are isolated Broadcast domains are isolated (do not forward layer 2 broadcast( Error Frames will not be forwarded Applied Network Research Group Department of Computer Engineering, Kasetsart University

/1616 Router Model l Application Presentation Session Transport Network Router Network Data Link Bridge Data Link Physical Repeater Physical Deal with Network Frame : operate at the Network Layer Applied Network Research Group Department of Computer Engineering, Kasetsart University