Introduction to LAN TDC 363 Week 2 Networking Hardware Book: Chapter 5 Topologies and Access Methods Book: Chapter 6

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Outline (Chap 5)

„ Network Equipment „ NIC „ Repeater and Hub „ Bridge and Ethernet Switch „ Router

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Network Adapters

„ Also called network interface cards (NICs) „ Connectivity devices enabling a workstation, server, printer, or other node to receive and transmit data over the network media „ Layer 2 device „ Why is NIC a LayerLayer--22 device?

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1 Types of Network Adapters

„ Old Days „ Industry Standard Architecture (ISA) „ MicroChannel Architecture (MCA) „ Extended Industry Standard Architecture (EISA) „ PihPeripheral lC Componen tItt Interconnect (PCI) „ PCI Express „ Personal Computer Memory Card International Association (PCMCIA) „ Universal Serial Bus (USB) „ Compact Flash (CF) Card „ NIC on Motherboard

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Installing and Configuring Network Adapter Hardware (a Historical Perspective)

„ Jumper „ Small, removable piece of plastic that contains a metal receptacle

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NIC Configuration Information

Ref. p. 240

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2 Hubs and Repeaters

„ LayerLayer--11 device „ Repeater: 2-2-portport hub „ Hub: mutimuti--portport repeater „ Connectivity device that regenerates digital signal „ Eliminate Noise (Attenuation) „ Signal received on one port is broadcast to all other ports

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Network of Hubs

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Bridges

„ Like a repeater, a bridge has a single input and single output port „ Unlike a repeater, it can interpret the data it retransmits „ LayerLayer--22 device

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3 Ethernet Switches switch ::= multimulti--portport bridge „ Divide a network into smaller logical pieces (multiple collision domains)

modular desktop or stackable

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CutCut--ThroughThrough Mode and Store and Forward Mode

„ CutCut--throughthrough mode „ Switching mode in which switch reads a frame’s header and decides where to forward the data before it receives the entire packet „ CutCut--throughthrough switches can detect runts, or packet fragments „ Store and forward mode „ Switching mode in which switch reads the entire data frame into its memory and checks it for accuracy before transmitting the information

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Delay in Store-Store-andand--ForwardForward

„ Max Frame Size 1500 bytes (12,000 bit) „ 10BaseT Network (10M bps) „ 12,000 ÷ 10M = 1,200 µsµs „ 100BaseTX N etwork (100M b ps) „ 12,000 ÷ 100M = 120 µsµs „ Gigabit Ethernet (1G bps) „ 12,000 ÷ 10M = 12 µsµs

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4 Routers

„ Multiport connectivity device „ Can integrate LANs and WANs running at different transmission speeds and using a variety of protocols „ Routers operate at the Network layer (Layer 3) of the OSI Model

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Routers

„ Modular router „ Router with multiple slots that can hold different interface cards or other devices

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Router Features and Functions

„ Filter out broadcast transmission to alleviate network congestion „ Prevent certain types of traffic from getting to a network „ Support simultaneous local and remote activity „ Provide high network fault tolerance through redundant components „ Monitor network traffic and report statistics to a MIB „ Diagnose internal or other connectivity problems and trigger alarms

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5 Router Features and Functions

„ Static routing „ Technique in which a network administrator programs a router to use a specified paths between nodes „ Dynamic routing „ Automatically calculates best path between nodes and accumulates this information in a routing table „ Hop „ Term used in networking to describe each trip data take from one connectivity device to another

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Router Features and Functions

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Routing Protocols

„ To determine the best path, routers communicate with each other through routing protocols „ In addition to its ability to find the best path, a routing protocol can be characterized according to its convergence tidbdidhhdime and bandwidth overhead „ Convergence time „ The time it takes for a router to recognize a best path in the event of a change or outage „ Bandwidth overhead „ Burden placed on an underlying network to support the routing protocol

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6 Routing Protocols

„ The four most common routing protocols: „ RIP (Routing Information Protocol) for IP „ RIPRIP--IIII „ OSPF (Open Shortest Path First) for IP „ EIGRP (Enhanced Interior Gateway Routing Protocol) for IP, IPX, and AppleTalk „ BGP (Border Gateway Protocol) for IP „ required for routing on the public Internet

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Brouters and Routing Switches

„ Bridge router „ Also called a brouter „ Industry term used to describe routers that take on some characteristics of bridges „ Routing switch „ Router hybrid that combines a router and a switch

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Gateways

„ Standard definition: a layerlayer--77 device to interconnect two distinct networks. „ Practical definition: a device to interconnect two networks. „ Combination of networking hardware and software that connects two dissimilar kinds of networks „ Popular types of gateways include: „ EE--mailmail gateways „ IBM host gateways „ Internet gateways „ LAN gateways

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7 HigherHigher--LayerLayer Switches

„ Switch capable of interpreting Layer 3 data is called a Layer 3 switch „ What is the difference between a Layer 3 switch and a router? „ Switch capable of interpreting Layer 4 data is called a Layer 4 switch „ What kdfkind of layer 4 d ata is used to switch? „ These higherhigher--layerlayer switches may also be called routing switches or application switches „ LayerLayer--77 switch ??? „ Confusion in terminology???

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Chapter Outline (Chap. 6)

„ LAN Topology „ WAN Topology „ Ethernet „ Token Ring „ Other LAN Technologies: „ FDDI and ATM

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Simple Physical Topologies „ Physical topology „ Physical layout of a network „ A Bus topology consists of a single cable, called a bus, connecting all nodes on a network without intervening connectivity devices

Q: any problem with this topology?

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8 Ring Topology

„ Each node is connected to the two nearest nodes so the entire network forms a circle „ One method for passing data on ring networks is token passing

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Star Topology „ Every node on the network is connected through a central device

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StarStar--wiredwired Ring Topology

„ Hybrid topology „ Complex combination of the simple physical topologies „ StarStar--wiredwired ring „ StarStar--wiredwired topologies use physical layout of a star in conjunction with token ring-ring-passingpassing data transmission method

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9 StarStar--wiredwired Bus Topology

„ In a starstar--wiredwired bus topology, groups of workstations are starstar--connectedconnected to hubs and then networked via a single bus

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EnterpriseEnterprise--WideWide Topologies

„ Enterprise „ An entire organization „ Backbone networks „ SilbkbSerial backbone „ Distributed backbone „ Collapsed backbone „ Parallel backbone

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Serial & Distributed Backbone

„ Serial backbone „ Two or more hubs connected to each other by a single cable „ Distributed backbone „ Hubs connected to a series of central hubs or routers in a hierarchy

Serial Backbone

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10 Collapsed Backbone

„ Collapsed ::= divide a single collision domain into multiple ones „ Uses a router or switch as the single central connection point for multiple subnetworks

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Parallel Backbone

„ Collapsed backbone arrangement that consists of more than one connection from central router or switch to each network segment Ref: Figure 6-10: A parallel backbone network

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Logical Topologies

„ Refer to the way in which data are transmitted between nodes „ Describe the way: „ Data are packaged in frames „ Electrical pulses are sent over network’s physical media „ Logical topology may also be called network transport system „ Communication at layer 2.

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11 Switching

Circuit Message Packet Switching Switching Switching

Frame Cell Switching Switching

Discussion: switching vs. transmission. What are the differences? Note: ATM is NOT a circuit switching technology.

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Practical Questions

„ As a network engineer, you are assigned to design a campus network. „ What is the technology to be deployed at the entrance facility? „ From carrier ’ s central office „ From the main building of the campus „ What is the technology to be deployed at the equipment room? „ What is the technology to be deployed at the telecom closet? „ What is the technology to be deployed at the work area (i.e., desktop)?

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What are my choices?

„ Ethernet „ 10BaseT, 10Base2, 10Base5 „ Fast Ethernet „ 1G and 10G Ethernet „ TTkoken Ri ng „ 100BaseVG „ FDDI „ ATM „ [Wireless]

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12 Ethernet

„ Most popular industry use and acceptance „ Product availability „ Many vendors „ Relatively low cost „ High knowledge base „ Standardized for multiple media types „ Twisted pair (10M, 100M, and 1G) „ Optical fiber (10M, 100M, 1G, and 10G) „ Coaxial cable (10Base2, 10Base5)

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Ethernet Standards

„ Specifications Ethernet standards define Physical and MAC layers of the OSI model only. „ Physical layer „ Electrical characteristics of cable cable connectors, including maximum lengths „ Bit encoding (e.g., Manchester coding) and transmission rate (10/100/1000 Mbps) „ Medium Access Control (MAC) layer „ Ethernet frame format and addressing „ Access protocol = Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

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Ethernet Standards --HistoryHistory

„ Early Standards „ Digital (DEC), Intel, and Xerox (DIX) published two Ethernet standards: Ethernet 1.0 (1980) and Ethernet 2.0 (1982). „ DIX Ethernet 2.0 is compatible with IEEE 802.3 Ethernet. Ethernet 1.0 is not compatible with modern systems. „ 10Base5 (1985) „ 10Base2 (1988) „ 1Base5 (1988) „ 10BaseT (1990) „ 100BaseT / 100BaseF (1995) „ 1000BaseX / 1000BaseT (1998/1999) „ 10GB Ethernet –802.3ae (2002)

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13 Ethernet

„ Carrier Sense Multiple Access with Collision Detection (CSMA/CD) „ The access method used in Ethernet „ Collision „ In Ethernet networks, the interference of one network node’s data transmission with another network node’s data transmission „ Jamming „ Part of CSMA/CD in which, upon detection of collision, station issues special 3232--bitbit sequence to indicate to all nodes on Ethernet segment that its previously transmitted frame has suffered a collision and should be considered faulty

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CSMA/CD Algorithm

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Ethernet Collision Domain

„ On an Ethernet network, an individual network segment is known as a collision domain „ Portion of network in which collisions will occur if two nodes transmit data at same time „ Data propagation delay „ Length of time data take to travel from one point on the segment to another point „ The last bit must be sent out before the first bit arrives at the farthest end of the network

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14 55--44--33 Rule (10Base#) 5 segments, 4 repeaters, 3 populated segments

hub/repeater

10Base2

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Ethernet Frame

„ Padding „ Bytes added to data portion of an Ethernet frame to make sure this field is at least 46 bytes in size „ Ethernet frame types ( caveat) „ IEEE 802.3 (“Ethernet 802.2” or “LLC”) „ Novell proprietary 802.3 frame (or “Ethernet 802.3”) „ Ethernet II frame „ IEEE 802.3 SNAP frame

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Ethernet Frame

Q1: What is the size of Ethernet address (known as MAC Address)? Q2: What is the minimum size of an Ethernet frame? Note: the answer is NOT 72 (why?)

Preamble: for circuit synchronization SFD: Start of Frame Delimiter

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15 Ethernet Address

„ Also known as Media Access Control (MAC) address „ Six bytes „ Block ID (3 bytes): unique to a vendor „ Device ID (3 bytes): unique to a device „ Exercise: „ How do you find the MAC address of your PC? „ How do you find the MAC address of the PC next to you? „ If your PC has two Ethernet cards, do you have one MAC address or two MAC address?

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Switched Ethernet

„ Traditional Ethernet LANs, called shared Ethernet, supply fixed amount of bandwidth that must be shared by all devices on a segment „ Switch „ DiDevice t hat can separate networ k segments into sma ller segments, with each segment being independent of the others and supporting its own traffic „ Switched Ethernet „ Newer Ethernet model that enables multiple nodes to simultaneously transmit and receive data over logical network segments

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Switched Ethernet

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16 Bridges „ Filtering database „ Collection of data created and used by a bridge that correlates the MAC addresses of connected workstations with their locations „ Also known as a Bridge Forwarding Table, MAC Address Table, MAC Forwarding Table, Source Address Table, Content Address Memory

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Bridge Forwarding Table (I)

P4 P1

P2 P3

99:88 :77 :22 :22 :22 99:88:77:44:44:44 99:88:77:66:66:66

99:88:77:33:33:33 99:88:77:11:11:11 99:88:77:55:55:55

P1 99:88:77:11:11:11 P3 99:88:77:44:44:44 P1 99:88:77:22:22:22 P4 99:88:77:55:55:55 P2 99:88:77:33:33:33 P4 99:88:77:66:66:66

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Notes on Switch and MAC Address

„ MAC address is used for transmission within an IP subnet. When data is sent to another IP subnet, IP address is needed. „ A rou ter separates LAN into m ultiple IP su bnet, and an Ethernet switch learns all MAC addresses of its own IP subnet. „ Ethernet switch on one IP subnet does NOT learn MAC addresses of another IP subnet.

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17 Bridge Forwarding Tables (II)

Network Network 192.168.1.0 192.168.2.0 99:88:77:11:11:11 99:88:77:22:22:22 P1 P2 SW1 P11 P21 SW2

P12 P13 P14 P22 P23 P24

192.168.1.10 192.168.1.12 192.168.2.10 192.168.2.12 11:22:33:01:01:01 11:22:33:03:03:03 11:22:33:04:04:04 11:22:33:06:06:06 192.168.1.11 192.168.2.11 11:22:33:02:02:02 11:22:33:05:05:05

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Bridge Forwarding Table (II(II--cont.)cont.)

Network Network 192.168.1.0 192.168.2.0 99:88:77:11:11:11 99:88:77:22:22:22 P1 P2 SW1 P11

P12 P13 P14 Port MAC Address P11 99:88:77:11:11:11 P12 11:22:33:01:01:01 192.168.1.10 192.168.1.12 P13 11:22:33:02:02:02 11:22:33:01:01:01 11:22:33:03:03:03 192.168.1.11 P14 11:22:33:03:03:03 11:22:33:02:02:02

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MAC Forwarding Table of SW2

Network Network 192.168.1.0 192.168.2.0 99:88:77:11:11:11 99:88:77:22:22:22 P1 P2 P21 SW2

Port MAC Address P22 P23 P24

P21 99:88:77:22:22:22 P22 11:22:33:04:04:04 192.168.2.10 192.168.2.12 P23 11:22:33:05:05:05 11:22:33:04:04:04 11:22:33:06:06:06 192.168.2.11 P24 11:22:33:06:06:06 11:22:33:05:05:05

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18 Ethernet – problem with loop

The network will be flooded with broadcast messages quickly.

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IEEE 802.1D Spanning Tree Algorithm and Protocol (STP)

Solution: STP blocks certain switch ports so that the network is transformed from a loop topology to a loop-free topology (or a tree topology). Also note that the connectivity must be maintained after the STP calculation.

()(root)

blocked port New standard with faster failover time: RSTP (802.1w)

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Using Switches to Create VLANs

„ Virtual local area networks (VLANs) „ Network within a network that is logically defined by grouping its devices’ switch ports in the same broadcast domain „ Broadcast domain „ Combination of ports that make up a Layer 2 segment and must be connected by a Layer 3 device „ Collision domain vs. Broadcast domain

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19 Using Switches to Create VLANs

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VLAN Challenge

SW1 SW2 SW3

WS1 WS2 WS3 WS4 WS5 WS6

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Solution –VLAN Trunking

SW1 SW2 SW3

WS1 WS2 WS3 WS4 WS5 WS6

VLAN Trunk: a physical link that carries Ethernet frames of multiple VLANs Question: how do we distinguish frames of different VLANs?

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20 Tagged MAC Frame

(IEEE 802.1Q standard)

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VLAN Router (R)

SW1 trunk SW2 SW3 trunk trunk

WS1 WS2 WS3 WS4 WS5 WS6

WS1 => WS6 (L2 Comm): WS1 => SW1 => SW2 => SW3 => WS6 WS1 => WS2 (L3 comm): WS1 => SW1 => SW2 => R => SW2 => SW1 => WS2

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Competing LAN Technologies

However, there is really no competition against Ethernet.

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21 Token Ring „ Standard: IEEE 802.5 „ Standard Speeds: 4M and 16M bps. „ Token Ring networks use the token passing routine and a starstar--ringring hybrid physical topology „ The 100-Mbps Token Ring standard is known as HighHigh--SpeedSpeed Token Ring (HSTR) „ On a Token Ring network, one workstation, called the active monitor, acts as the controller for token passing

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Token Ring (w/ MAU)

„ Multistation Access Unit (MAU) „ Regenerates signals

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Ethernet vs. Token Ring

„ You may argue 1 or 2 advantages of token ring over shared Ethernet. „ More efficient use of bandwidth „ Fairness to each workstation „ There are no arg u ments when comparing with switched Ethernet. „ You may still find token ring today, but it is very unlikely to deploy a new network with token ring.

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22 „ Logical topology whose standard was originally specified by ANSI in midmid-- 1980s and later refined by ISO

Fiber Distributed Data Interface (FDDI)

Used to be a popular technology at the campus backbone, but not any more. Why?

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Asynchronous Transfer Mode (ATM)

„ Logical topology that relies on a fixed packet size to achieve high data transfer rates of DS3 (45M), OCOC-- 3 (155M), OCOC--1212 (622M), and more „ The fixed packet in ATM is called a cell (53 bytes) „ A unique aspect of ATM technology is that it relies on virtual circuits „ ATM uses circuit switching, which allows ATM to guarantee a specific quality of service (QOS)

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IP/Ethernet over ATM

„ Multiple Encapsulation over ATM (RFC 2684) IP Ethernet RFC 2684 ATM

„ Classical IP over ATM (RFC 1577) „ ATM LAN Emulation (LANE) „ Multiprotocol over ATM (MPOA)

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23 Review Questions

„ What is the OSI layer for the following networking device: NIC, repeater, hub, bridge, Ethernet switch, router „ What is the IRQ of your Ethernet PCI adapter? „ Can you support full duplex with a hub? Why? „ What is the difference between a hub and an Ethernet switch? „ What is the difference between an Ethernet frame and a tagged EEhthernet frame ? „ What is a router? For a typical home network, do you need a router? Give an example that you will need one and another example that you do not need one. „ Describe the difference between static routing and dynamic routing. What are routing protocols? Given three examples of routing protocols. What is the routing protocol used on THE INTERNET?

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Review Questions (cont.)

„ Give an example for the following network topologies: bus, ring, and star. „ Comparison of three switching thnlitechnologies: cir iritmcuit, message, and ndpkt packet. Which one is used on the data networking today? „ Describe the process flow of CSMA/CD.

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Chapter Summary (cont.)

„ Describe the differences (advantages and disadvantages) of cutcut--throughthrough and store-store-andand-- forward modes employed in the Ethernet switch. „ SiTAlih(STA)WhiSTA?Spanning Tree Algorithm (STA): What is STA? Why do we need it? What will be the problems if you do not apply STA? Can you draw two diagrams showing a network (logical and physical) topology with and without STA?

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24 Review Questions (cont.)

„ What are the differences between shared Ethernet and switched Ethernet? „ Given a switched Ethernet network, populate the MAC forwarding table on each Ethernet switch. „ List all Ethernet standards and their speed. „ What is the mix and max Ethernet frame size (802.3 and 802.1Q frame)? „ Why is VLAN trunk and why is it needed? Draw a diagram to show how VLAN tagging is used.

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Review Questions (cont.)

„ Token Ring: „ What is a token? „ Draw an example of network diagram for token ring „ What is the top speed of token ring? „ HowwwWy is FDDI used on the network? Will you consider FDDI for a new network deployment? Why? „ ATM: Is ATM a viable technology for LAN deployment? Why?

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Lab Exercise

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25 TDC363 –Lab01– Lab01

LAN Lab Core SW Internet LAN Lab Router

SW01 (192.168.1.1)

140.192.40.5 SW02 (192.168.1.2) 192.168.1.5

Linux-05 140.192.40.7 192.168.1.7 Windows-07

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Linux Access

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Ethernet Switch Access

telnet 192.168.1.1 (SW01) telnet 192.168.1.2 (SW02)

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26 MACMAC--AddressAddress-- Table

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show interface (physical port)

Note that each physical port (interface) has a MAC address.

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