CN2668 Routers and Switches Kemtis Kunanuraksapong MSIS with Distinction MCTS, MCDST, MCP, A+

Agenda o Chapter 2: Network Devices o Exercise o Quiz

Repeaters o Attenuation o Degradation of signal clarity o Repeats every signal, 0 or 1 o Function at Layer 1 o If the network use the same data type and packet structure, a repeater can be used as a connection device. (twisted-pair cable and coaxial)

Hubs o Active hub o The hub that repeat AND amplify signal o Passive hub o Merely connects cables to form a network o Often form a Star Topology; see Figure 2-3 on Page 27

Summary of Repeaters / Hubs o Advantages o Extend a network’s total distance o Do not serious affect network performance o Disadvantages o Cannot connect different network architectures such as Token ring and Ethernet o Do not reduce network traffic o Do not segment the network

Wireless Access Points o Standards and Organization o a/b/g/n o See Table 2-1 on Page 29 o All the devices share the same bandwidth o Two modes o Ad hoc mode o Basic service set (BSS) / Extended Service Set (ESS)

Wireless Access Points o Service Set Identifier (SSID) o Broadcast / Hide o Wireless Security Measures o 802.1x o Function at layer 1 o Extensible Authentication Protocol (EAP) o Function at layer 2

Wireless Access Points o Security options o WEP (Wired Equivalent Privacy) o WPA (Wi-Fi Protected Access) o WPA2 o i o See Table 2-2 on Page 31

Wireless Access Points o Troubleshooting o Make sure your wired LAN is working o Complete a wireless site survey to determine access point placement o Install the access point(s) with no security o Attempt to associate to the access point with a laptop o Configure security on both the access point and the client o Verify connectivity at all layers

Wireless Access Points o Possible degradation of wireless signal o Interference from too much overlap of one access point’s cell range onto another o Incompatible standard (a/b/g/n) o Antennas is not securely connected and in optimal position o Sources of interference such as large bodies of water, metal building, cordless phone, etc.

Summary of WAP o Advantages o Provide mobility o Extend the range of the network without running additional wires o Disadvantages o Security concerns o Provide less bandwidth than wired devices

Network Segmentation o To segment the network into smaller collision domain o Bandwidth are shared among all nodes, hence segmentation improve the bandwidth o See Figure 2-5 on Page 33 o Bridges o Switches o Routers

Bridges o Layer 2 device o Filter traffic between segments by examining the destination MAC address o Map MAC addresses to bridge segment o Forwards / drops the frame o If broadcast frame has been sent, the bridge will forward to every node except the sender

Bridges o Transparent Bridges o Build the MAC table as they receive frames o Source-Routing Bridges o Rely on the source of the frame transmission to provide the routing information o The source determines the best path by sending out explorer frames o The destination determines best routes and response back

Bridges o Translation Bridges o Can connect networks with different architecture o Act as transparent bridges to Ethernet host o Act as source-routing bridges to Token Ring host

Summary of Bridges o Advantages o Extend a network by acting as a repeater o Reduce network traffic on a segment by subdividing network communications o Increase available bandwidth o Reduce collisions o Disadvantages o Slower than and more expensive than repeaters and hubs o Does not filter broadcast traffic

Switches o Function at Layer 2 o Reduces the number of frames transmitted o Virtual circuit o A connection between source and destination o Filters based on MAC addresses and mapped to port

Summary of Switches o Advantages o Increase available bandwidth o Reduce collisions o Disadvantages o More expensive o Broadcast traffic maybe troublesome

Routers o Operates the same way as bridges and switches o Use the logical address (IP address) at Layer 3 o Every interface represents a different network o Create collision domains as well as broadcast domains

Summary of Routers o Advantages o Connect different network architectures o Choose the best path using dynamic routing o Reduce traffic by creating collisions and broadcast domains o Disadvantages o Work only with routable network protocols o Dynamic router communication cause additional overhead o Slower than others since the packet must be analyzed from layer 1 to 3

Brouters o A bridge + router o Can route both routable and nonroutable protocol o Can operate on both layer 2 and 3

Gateway o To translate between different protocol suites o Create the most latency o It convert the packet to another format

Ethernet Operations o IEEE o Carrier Sense Multiple Access with Collision Detection (CSMA/CD) o After sending packet, they have to wait 9.6 microseconds (Interframe gap IFG or Interpacket gap IPG) o Collisions o When packet sent, there will be carrier signal o If two host send out at the same time, one of them will send 32-bit jam signal

Ethernet Operations o Fast Ethernet (100BaseT) o 100 Mbps o IEEE 802.3u o Gigabit Ethernet (1000BaseX) o 1000 Mbps o IEEE 802.3ab

Ethernet Operations o Half- and Full-Duplex Communications o Telephone o Walkie-talkie o Smoke

Assignment o Review Questions o 1 – 28 o Case Projects o 4, 5