Chapter 2Review of Computer Network Technology
Outline
1. Network Topology2. Local Area Networks3. Network Node Components4. Internet TCP/IP Protocols
Refer to net-inrtro.ppt
5. Transmission Technology
1. Network Topology- LAN Topology
Figure 2.1(b) Ring Topology
Figure 2.1(a) Bus Topology
Ethernet
DTE DTE DTE
DTE DTE
DTE
DTEDTE
DTE
DTE
DTE
DTE
DTE
Figure 2.1(d) Hub Configurations
DTE
DTE
DTE
DTE
Token Ring HubEthernet Hub
Figure 2.1(c) Star Topology
DTE
DTE
DTE
DTE
DTE DTE
BusBus
RingRing
StarStar
A Campus NetworkOf LANs
1. Network Topology- WAN Topology
MeshMesh TreeTree
2. Local Area Network Type of LANs
Ethernet Fast Ethernet Gigabit Ethernet Half-duplex Vs Full-duplex Switched Ethernet VLAN (Virtual LAN) Token Ring FDDI
Ethernet
• IEEE 802.3 standard• 10 Mbps data rate• CSMA/CDCSMA/CD
• Carrier Sense Multiple Access with Collision Carrier Sense Multiple Access with Collision DetectionDetection
• Analogy of a hollow pipe• Back Off Algorithm
• Packet Size: 64 ~ 1500 bytes• Segment length and drop cable length
EthernetTable 2.1 Ethernet LAN Topology Limits
TYPE DESCRIPTION SEGMENT LENGTH DROP CABLE
10Base2 Thin coax (0.25”) 200 meters Not allowed
10Base5 Thick Coax (0.5”) 500 meters Twisted pair: 50 meters
10Base-T Hub topology N/A Twisted pair: 100meters
10Base-F Hub topology N/A 2 km
10Base-T : 10 Mbps, Baseband, Twisted Pair
Fast Ethernet
PMD Sublayer
Convergence Layer
MAC Sublayer
LLCData Link
Physical
Network
Figure 2.4 100Base-T Fast Ethernet Protocol Architecture
LLC Logical Link controlMAC Medium Access ControlPMD Physical Medium Dependent
LAN - IEEE 802.x
Network
Data Link
Physical
LLC
MAC
802.1 (HLI)
802.2
802.
5
802.
3
802.
4
HLI: High Level InterfaceLLC: Logical Link ControlMAC: Medium Access Control
802.1: HLI802.2: LLC802.3: Ethernet802.4: Token Bus802.5: Token Ring
100 Mbps 100Base-T PMD (Physical Medium Dependent) subl
ayer – to be consistent with IEEE 802.3 UTP Category 5
Fast Ethernet
Gigabit Ethernet IEEE 802.3z 1 Gbps Packet size: 512 bytes
Table 2.2 Gigabit Ethernet Topology Limits
9micronSingle-Mode
50micronSingleMode
50 micronMultimode
62.5micron
Multimode
BalanceShielded
Cable
UTP
1000BASE-LX 10 km 3 km 550 m 440 m - -
1000BASE-SX - 550 m 260 m - -
1000BASE-CX - - - 25 m -
1000BASE-T - - - - 100 m
Full-Duplex Ethernet Half-Duplex Full-Duplex Coaxial Cables can not support full-dupl
ex. UTP + Hub with full-duplex support 10Base-T, 100Base-T, 100Base-F
↓ 10Base-Tx, 100Base-Tx, 100Base-Fx
Switched EthernetSwitched HubMulti-Port Bridge=
Virtual LAN
Advantages of VLAN
Performance Formation of Virtual Workgroups Simplified Administration Reduced Cost Security
Token Ring
DTE 4
DTE 3DTE 1
DTE 2
Figure 2.11 Token Ring LAN
TokenRing
3 to 1 ACK
1 to 3 MSG
DTE 1 hastoken control
IEEE 802.5
Dual Ring TR LAN
Figure 2.12(a) Token Ring Dual Ring Management
DTE 4
DTE 3DTE 1
DTE 2
RedundantRing
PrimaryRing
Failure Recovery in TR LAN
FDDI
• Fiber Distributed Date InterfaceFiber Distributed Date Interface• Uses fiber optics medium• Modified token ring protocol• Data rate 100 Mbps• Up to 500 DTEs in a single segments of 100 km wi
thout repeaters• Ideal for campus backbone network• Single and dual attached stations (SAS and DAS)• Dual attached stations load share the two rings
Dual Ring FDDI Network
Figure 2.13(a) Dual Ring FDDI Network Configuration
DAS
SASSAS
DAS
SAS Single Attached StationDAS Dual Attached Station
LAN Data Rate Race
E’Net10Mbps
FDDI100 Mbps
Fast E’Net100Mbps ATM
155.52 Mbps
Gbit E’Net1 Gbps
DuplexE’nets
ATMOC-n
3. Network Node Components
• Hubs• Bridges• Remote bridges• Routers• Gateways• Half bridge / half router• Switches
Basic Network Nodes
SwitchSwitch
BridgeBridge
RouterRouter
GatewayGateway
Networked Components
Hubs• Hub is a platform with multiple ports• Function dependent on what is housed
• LAN multi-port repeater• Switched LAN bridge (switched hub)
Stacked Hub
Bridges
Bridge
Local Bridge Remote Bridge
Simple
Multiport
MultiportMulti-protocol
Refer to Figure 2.17, page 77
Bridges Operates at Layer 2, the data link layer. Allows networks with different physical signaling, but
with compatible data link addressing schemes, to communicate.
Helps reduce traffic on a backbone LAN by filteringfiltering any information coming from one segment to another that does not need to be forwarded through the backbone.
A common use for a bridge is to allow users on an Ethernet LAN and a Token Ring LAN to communicate with each other.
Bridges Remote Bridges
Used to connect remote LANs Transparent Bridges
Used to connect LANs of the same types Use a Spanning Tree Algorithm for routing
Backward learning Routing Table of ports associated with destination addresses
Source Routing Bridges Used to network token-ring LANs Source is aware of the entire path to the destination.
Routers
• Routers operate at network layer• Routes packets between nodes of similar
network protocols• Routing table used to route packets• DLC and Physical layers could be different
under the same common network layer protocol
A Router Configuration
Gateway
• Gateway is router connecting two networks with dissimilar network protocols
• Gateway does the protocol conversion at the network layer
Protocol Converter• Protocol converterProtocol converter does the conversion at the
application layer
Gateway Configuration
Protocol interface
Physical medium
TP
NP
DP
Phy
TP
NP'
DP'
Phy'
Gateway
Network AProtocol P
Network BProtocol Q
Gateway
NP
DP
Phy
NP'
DP'
Phy'
Figure 2.22 Gateway Configuration
Tunneling Using Multiprotocol Routers
IP
MultiprotocolRouter
X.25
MultiprotocolRouter
IP
Ethe
rnet
Ethe
rnet
Tunnel
Figure 2.24 Tunneling Using Multiprotocol Routers
• Tunneling is transmission of packets (viamultiprotocol routers) by encapsulation
• In Figure 2.24, packets are encapsulated and transmitted through X.25 network in a serial mode
Half-Bridge/Half-Router•Half-bridge (half-router) is point-to-point communication
• Uses PPP protocol
• Helps low-end users to communicate with ISP on dial-up link saving the expense of dedicated link
• Router encapsulates packets in PPP frames and puts serial outputs to the bridge, and vice-versa
Switches
• Switches are embedded in bridges and routers• Switched network used in WAN• Two types of switched networks
• Circuit-switched• Packet-switched
• Datagram service• Virtual circuit
B
A D
C
DTE A DTE Z
Pkt3 Pkt2 Pkt1Pkt2 Pkt3 Pkt1
Pkt1Pkt3
Pkt2
Pkt2Pkt2
Figure 2.26(a) Datagram Configuration
B
A D
C
DTE A DTE Z
Pkt3 Pkt2 Pkt1Pkt3 Pkt2 Pkt1
Pkt3
Pkt2
Pkt1
Figure 2.26(b) Virtual Circuit Configuration
5. Transmission Technology
Transmission Technology
Medium Mode
Wired Wireless
LAN WAN
Digital Analog
LAN Mobile Satellite
Transmission MediaMedia
WirelineTransmission
WirelessTransmission
ElectricConductors
OpticalFiber
TwistedTwistedPairPair
CoaxialCoaxialCableCable
Mono-modeMono-mode Multi-modeMulti-mode
RadioRadio
MicrowaveMicrowaveSatelliteSatellite
TransmissionTransmission
InfraredInfrared
Laser LinksLaser Links
• Thin• Thick
• UTP• STP
Transmission ModesTransmission Modes
Figure 2.27(c) Cell Transmission (ATM)
Figure 2.27(b) Packet Transmission ( X.25)
User 1 User 2 User 3 User 4User 24
Time
Cha
nnel
Ban
dwid
th
Time
TimeDivision
Multiplexing(TDM)
User 2 User 3 User 4 User 5User 1
TimeB
andw
idth
Figure 2.27(a) T1 Time Division Multiplexing (TDM) Transmission
PacketMultiplexing
User 1
Ban
dwid
th
Time
User 3
User 4
User 2
User 3
User 1
5
User 1
User 4
User 1
User 1
5
CellMultiplexing
channel 2
channel 1
channel 24
TDM
PacketMultiplexing
CellMultiplexing