network components
Post on 19-Jun-2015
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Network Components
Session No.6
Network Components
Network Components
Network Components
• NIC (Network Interface Card)
• Repeater
• Hub
• Bridge
• Switch
• Router
• Gateway
• Different Network Domains
Network Components
Network Interface Card
Network Components
r NIC works in two modes:• General mode • Promiscuous mode
r In general mode, the Ethernet card of the computer will allow following types of packets:
• Packets send to the computer.• Broadcast Packet• Multicast packet and if computer is part of that
multicast group.r In promiscuous mode, the Ethernet card of the computer will
allow all the packets that it receives.
Network Interface Card
Network Components
1001 0011-1011 1011-0000 1101
Example: 00-00-E2-93-BB-0D
0000 0000-0000 0000-1110 0010
P/GG/U IEEE assigned
Vendor assigned
48 bits or 6 bytes
Manufacturer of the card
Ethernet Address Format
Network Components
Repeater
• A repeater receives a signal, regenerates it, and passes it on.
• It can regenerate and retime network signals at the bit level to allow them to travel a longer distance on the media.
Network Components
Hub
• Hubs are actually multiport repeaters.
• A typical repeater has just two ports, a hub generally has from four to twenty-four ports.
Network Components
Bridge
• There are times when it is necessary to break up a large LAN into smaller, more easily managed segments.
• The function of the bridge is to make intelligent decisions about whether or not to pass signals on to the next segment of a network.
• When a bridge receives a frame on the network, the destination MAC address is looked up in the bridge table to determine whether to filter, flood, or copy the frame onto another segment.
• If placed strategically, a bridge can greatly improve network performance.
Network Components
Switch• A switch is sometimes described as a multiport bridge.
• Switches build the forwarding table to determine the destination of data being sent by one computer to another computer on the network.
• Switching is a technology that alleviates congestion in Ethernet LANs by reducing the traffic and increasing the bandwidth.
• Benefits of using Switch:
• Ethernet switch allows many users to communicate in parallel through the use of virtual circuits and dedicated network segments in a virtually collision-free environment. This maximizes the bandwidth available on the shared medium.
• Another benefit is that moving to a switched LAN environment is very cost effective because existing hardware and cabling can be reused.
Network Components
Switch Contd.,
Network Components
• Address learning
• Forward/filter decision
• Loop avoidance
Three Switch Functions
Network Components
• Initial MAC address table is empty
MAC address table
0260.8c01.1111
0260.8c01.2222
0260.8c01.3333
0260.8c01.4444
E0 E1
E2 E3
A B
C D
How Switches Learn Host Locations?
Network Components
• Station A sends a frame to Station C• Switch caches station A MAC address to port E0 by learning the source address
of data frames • The frame from station A to station C is flooded out to all ports except port E0
(unknown unicasts are flooded)
MAC address table
0260.8c01.1111
0260.8c01.2222
0260.8c01.3333
0260.8c01.4444
E0: 0260.8c01.1111
E0 E1
E2 E3DC
BA
How Switches Learn Host Locations
Network Components
• Station D sends a frame to station C• Switch caches station D MAC address to port E3 by learning the source Address of
data frames• The frame from station D to station C is flooded out to all ports except port E3
(unknown unicasts are flooded)
MAC address table
0260.8c01.1111
0260.8c01.2222
0260.8c01.3333
0260.8c01.4444
E0: 0260.8c01.1111E3: 0260.8c01.4444
E0 E1
E2 E3 DC
A B
How Switches Learn Host Locations
Network Components
r Station A sends a frame to station Cr Destination is known, frame is not
flooded
E0: 0260.8c01.1111E2: 0260.8c01.2222E1: 0260.8c01.3333E3: 0260.8c01.44440260.8c01.1111
0260.8c01.2222
0260.8c01.3333
0260.8c01.4444
E0 E1
E2 E3
XX DC
A B
MAC address table
How Switches Filter Frames
Network Components
• Station D sends a broadcast or multicast frame
• Broadcast and multicast frames are flooded to all ports other than the originating port
0260.8c01.1111
0260.8c01.2222
0260.8c01.3333
0260.8c01.4444
E0 E1
E2 E3 DC
A B
E0: 0260.8c01.1111E2: 0260.8c01.2222E1: 0260.8c01.3333E3: 0260.8c01.4444
MAC address table
Broadcast and Multicast Frames
Network Components
Router• While a router can be used to segment LANs, its major use is as a WAN
device.
• They operate at Layer 3 of the OSI model, making decisions based on network addresses.
• The two main functions of a router are the selection of best path for and the switching of frames to the proper interface.
• Routers accomplish this by building routing tables and exchanging network information with other routers.
Network Components
Router Contd.,
Network Components
Gateway
• A node on a network that serves as an entrance to another network.
• A network gateway is an internetworking system, a system that joins two networks together.
• In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In homes, the gateway is the ISP that connects the user to the internet.
Network Components
Network Device Domains
Hub Bridge Switch Router
Collision Domains:
1 2 4 4
Broadcast Domains:
1 1 1 4
Network Components
Exercise for Participants
r Design a network by using different network components, servers and media. Design should start from ISP (Internet service provider).
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