Week One AgendaAttendanceAnnouncementsCourse descriptionReview previous week informationReview current week informationQuiz

Week One ReviewCourse Objective

This course was developed to parallel the Certified Design Professional (CCDP) certification.

Build upon the base level of the CCNA knowledge and experience.

Design simple routed LAN, routed WAN, and switched LAN and ATM networks.

Use Network-layer lists.

Filter with access lists.

Use and propagate VLAN.

Evaluate existing network components.

Week One ReviewHistory of Cisco

Len and Sandy Bosack, 1980s

Worked in different departments at Stanford University. They were having trouble getting their individual system to communicate.

Build a gateway server that made it easier for their disparate computers to communicate using the IP protocol.

Week One ReviewInternetworking Basics

Networks and networking have grown exponentially over the last 20 years. This technology has evolved at light speed just to keep up with the huge increases in basic mission-critical user needs. Currently, there is a basic need to use VoIP, increase transmission speeds, and combine voice, data, and video for medium and enterprise sized networks. This will involve the design of new and/or the re-design of existing networks.

Network is where data is sent and received via cables (e.g., telephone lines or fiber optics ) or wireless relay systems. Networks contain a variety of hardware devices and software implementations to accomplish transmitting data.

Week One Review

Internetworking Basics

Network segmentation is the breaking up of a large network into smaller networks. Routers, switches, and bridges are used to create network segmentation.

Routers are used to connect networks together and route packets of data from one network to another. By default, they break up broadcast domains.

Week One ReviewInternetworking Basics

Switch is a device responsible for multiple functions such as filtering, flooding, and sending frames. It works using the destination address of individual frames. By default, switches break up collision domains.

Bridges is a device for connecting two segments of a network and transmitting packets between them. Both segments must use identical protocols to communicate. Their purpose is to filter, send, or flood any incoming frame, based on the MAC address of that particular frame.

Broadcast domain is a group of devices receiving broadcast frames initiating from any device within the group. Because they do not forward broadcast frames, broadcast domains are generally surrounded by routers.

Collision domain is the network area in Ethernet over which frames that have collided will spread. Collisions are propagated by hubs and repeaters, but not by LAN switches, routers, or bridges.

Week One ReviewInternetworking Models

Open Systems Interconnection (OSI) reference model was introduced in the late 1970s. Created by the International Organization for Standardization.

Why was standardization needed? This standard was created to allow computing installations to incorporate multiple vendor hardware and software products within their operation. Prior to this standardization, computers could only communicate with computers from the same manufacturer.

Week One ReviewLayered Approach

A reference model is a conceptual blueprint of how communications should take place. It addresses all the processes required for effective communication and divides these processes into logical groupings called layers. Designs such as the OSI Model, are known as layered architecture.

Example: Start up company. Identify the tasks involved. Group similar tasks into departments. These departments are a metaphor for the layers in this scenario.

Week One Review

Layered Approach

Similarly, software developers can use a reference model to understand computer communication processes and see what types of functions need to be accomplished on any one layer. If they are developing a protocol for a certain layer, they only want to focus themselves with this specific layers functions, not those of any other layer. Another layer and protocol will handle the other functions.

Week One ReviewLayered Approach

Advantages of using the OSI layered model are:

Allows multiple-vendor development through standardization of network components.

Allows various types of network hardware and software to communicate.

Allows changes in one layer from affecting other layers, so it doesn’t hamper development.

Week One ReviewOSI Model

The top three layers define how the applications within the end stations will communicate with each other and with users. The bottom four layers define how data is transmitted end-to-end.Application provides a user interfacePresentation presents data and handles encryptionSession keeps different applications data separate.Transport provides reliable or unreliable delivery.Network provides logical addressingData Link provides access to media using MAC addressPhysical moves bits between devices, specifies voltage, wire speed, and pin-out of cables.

Week One ReviewOSI Model

Application - File, print, message, database, and application

Presentation – Data encryption, compression, and translation services

Session – Dialog control

Transport – End-to-end connection

Network – Routing

Data Link - Framing

Physical – Physical topology

Week One ReviewOSI Model

Network devices that operate at all seven layers of the OSI model include:

Network management stationsWeb serversGatewaysNetwork hosts

Week One ReviewOSI Model

Flow control is implemented at the transport layer to prevent the receiving host buffers from being overflowed by the send host. This is an event that can result in data loss. Reliable data transport employs a connection-oriented communications session between systems, and the protocols involved ensure that the following is achieved: The segment delivered are acknowledged back to the sender upon their reception.Any segments not acknowledged are retransmitted.Segments are sequenced back into proper order upon arrival at their destination.A manageable data flow is maintained in order to avoid congestion overloading, and data loss.

Week One ReviewOSI Model

Connection-Oriented communications is a transport operation. One device first establishes a connection-oriented session with its peer system. This is called three-way handshake. Data is then transferred, and when finished, a call termination takes place to tear down the virtual circuit.

Week One ReviewOSI Model

Connection-oriented communications three-way hand shake.

Synchronize ->Negotiate connection <->Synchronize <-Acknowledge ->Connection established Data transfer (send segments) <->

Week One ReviewOSI Model

Buffer is used when a machine receives a flood of datagram's to quickly for a process to handle. Buffering can only solve the problem temporarily if the burst is small. If the flood of datagram's is too intense and the capacity is exhausted, it will discard any additional datagram's that arrive.

Week One ReviewOSI Model

Windowing is a flow control (Transport layer) method used with TCP at the Transport layer. Windows are used to control the amount in outstanding, unacknowledged data segments.The data and route update packets are used at the Network layer. The data packet to transport user data through the internetwork. Route update packets are used to update neighboring routers about the networks connected to all routers within the internetwork.

Week One ReviewOSI Model

Protocols that send route update packets are called routing protocols; examples of some common ones are RIP, EIGRP, and OSPF.Network addresses are protocol specific network addresses. A router must maintain a routing table for individual routing protocols because each routing protocol keeps track of a network with a different addressing scheme.Interface is the exit interface a packet will take when destinated for a specific network.

Week One ReviewOSI Model

Metric is the distance to the remote network. Different routing protocols use different ways of computing this distance. Hop count is the number of routers a packet passes through en route to a remote network.The Media Access Control (MAC) defines hoe packets are placed on the media. Contention media access is “first come/first served” access where everyone shares the same bandwidth. MAC is a Data Link layer function.

Week One ReviewOSI Model

Logical Link Control (LLC) is a sublayer responsible for identifying Network layer protocols and then encapsulating them. An LLC header tells the Data Link layer what to do with a packet once the frame is received.

Week One ReviewTCP/IP Model

The TCP/IP model is basically a condensed version of the OSI model. It is composed of four layers.Process/Application is the integration of the first three layers of the OSI Model. The Presentation/Application layer defines protocols for node-to-node application communication and also controls user-interface specifications.

Week One Review

TCP/IP ModelHost-to-Host parallels the Transport layer , defining protocols for setting up the level of transmission service for applications. Issues are addressed like reliable end-to-end communication and ensuring the error-free delivery of data. It handles packet sequencing and maintains data integrity. In summary, this layer shields the upper three layers from the Internet layer.

Week One Review

TCP/IP ModelInternet layer exists for routing, and providing a single network interface to the upper layers.Network Access bottom layer that handles similar functions as the Data Link and Physical layers. It provides media access.

Week One ReviewInternetwork Devices

Hubs are really multiple port repeater found at the Physical layer. A repeater receives a digital signal and reamplifies or regenerates that signal, and then forwards the digital signal out all active ports without looking at any data. Physical layer functionThe switches and bridges work at the Data Link layer and filter the network using hardware (MAC) addresses.

Week One ReviewEthernet Networking

Ethernet is a contention media access method that allows all hosts on a network to share the same bandwidth of a link. Ethernet is popular because it’s readily scalable, meaning it’s comparatively easy to integrate new technologies, like FastEthernet and Gigabit Ethernet, into an existing network infrastructure.Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD).

Week One ReviewEthernet Networking

CSMA/CD is a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium. This protocol was created to overcome the problem of those collisions that occur when packets are transmitted simultaneously from different nodes.

Week One ReviewEthernet Networking

A good collision management protocol is needed like CSMA/CD because when a node transmits in a network, all other nodes on the network receive and examine that transmission. Only bridges and routers can effectively prevent a transmission from propagating throughout the entire network.

Week One ReviewHalf- and Full-Duplex Ethernet

Half duplex uses only one wire pair with a signal running in both directions on the wire.Half duplex Ethernet typically 10BaseT.Full-duplex uses two pairs of wires. It uses a point-to-point connection between the transmitter of the transmitting device and the receive of the receiving device. There are no collisions to worry about because now it’s like a freeway with multiple lanes instead of the single-lane road provided by half-duplex.

Week One ReviewHalf- and Full-Duplex Ethernet

Typical speeds are 10Mbps, 100Mbps, and 200Mbps for FastEthernet. Full-duplex Ethernet can be used in three situations:With a connection from a switch to a host.With a connection from a switch to a switch.With a connection from a host to a host using a crossover cable.

Week One ReviewEthernet at the Data Link LayerEthernet at the Data Link layer is responsible for

Ethernet addressing, framing packets received from the Network layer and preparing them for transmission on the local network through the Ethernet contention media access method.

Week One ReviewEthernet at the Data Link LayerThere are four different types of Ethernet frames

available:Ethernet_IIIEEE 802.3IEEE 802.2SNAP

Week One ReviewEthernet at the Data Link Layer

Ethernet addressing uses the Media Access Control (MAC) burned into each and every Ethernet Network Interface Card (NIC). The MAC, or hardware address, is a 48 bit address written in a hexadecimal format.

Week One ReviewEthernet at the Physical Layer

Ethernet was first implemented by a group called DIX (Digital, Intel, and Xerox). They created and implemented the first Ethernet LAN specification, which the IEEE used to create the IEEE 802.3 Committee. This was a 10Mbps network that ran on coax, twisted-pair, and fiber physical media. The IEEE extended the 802.3 to two new committees known as 802-3U (FastEthernet) and 802.3Z (Gigabit Ethernet).

Week One ReviewEthernet CablingStraight-Through CableThis type of Ethernet cable is used to connect:

Host to switch or hub (h/s <--> host)Router to switch or hub (h/s <--> router)

Crossover CableThis type of Ethernet cable is used to connect:

Switch to switch (h/s <--> h/s)Hub to hubHost to host

Week One ReviewEthernet CablingRolled Cable

A rolled Ethernet cable can be used to connect a host to a router console serial communication (com) port.(host <--> Router/Switch)

Week One ReviewData Encapsulation

Encapsulation is a technique used by layered protocols in which a layer adds header information to the Protocol Data Unit (PDU) from the layer above.

Week One ReviewData EncapsulationApplicationPresentationSessionTransport – PDU (Segment) TCP header/DataNetwork – PDU (Packet) IP header/DataData Link – PDU (Frame)

LLC header/Data/FCSMAC header/Data/FCS

Physical – PDU (Bits) 0101110101010101

Week One ReviewSerial Transmission

Wide area network (WAN) services are typically dedicated leased lines using High-Level Data Link Control , Point-to-Point (PPP), Integrated Services Digital Network (ISDN), and Frame Relay. Typical speeds run at 2400bps to 1.544 Mbps (T-1).WAN serial connectors use serial transmission, which is one bit at a time, over a single channel. Parallel transmission sends at least 8 bits at a time.

Week One ReviewData Terminal Equipment and Data

Communication Equipment What is a DTE and DCE?DTE – router interface and they connect into DCE. A channel service unit/data service unit (CSU/DSU). The CSU/DSU then plugs into a demarcation location (demarc) and is the service provider’s last responsibility. The demarc is usually an RJ-45 female connector located near your equipment.

Week One ReviewData Terminal Equipment and Data

Communication Equipment A DCE supplies the physical connection to the network, forwards traffic, and provides a clocking signal to synchronize data transmission between DTE and DCE devices.

Handout network product icons

Week One

Routing ProtocolsAdministrative distance (AD) is used to rate the trustworthiness of routing information received on a router from a neighboring router. AD values range from 0 to 255, where 0 is the most trusted and 255 means no traffic will pass via this route.

Week One

Routing ProtocolsRoute Source Default AD

Connected interface 0Static route 1EIGRP (Cisco) 90IGRP (Cisco) 100OSPF 110RIP 120External EIGRP 170

Week One

Cisco Three Layer Hierarchical ModelA hierarchy helps us to understand where things belong, how things fit together, and what functions go where. It brings order and understandability to otherwise complex situations.Cisco’s network design model represents the following three layers:

Core LayerDistribution LayerAccess Layer

Week OneCisco Three Layer Hierarchical Model

The core layer is responsible for transporting large amounts of traffic both reliably and quickly. The main purpose of the network’s core layer is the switch traffic as fast as possible. The traffic transported across the core is common for a majority of users. If there is a failure at the core layer, every user can be affected. Fault tolerance at this layer is a critical issue.

Week OneCisco Three Layer Hierarchical Model

The core layer must be concerned about high levels of traffic, and the speed and latency of the traffic.Things you don’t want to do.Do anything to slow down traffic. This includes adding access liosts, routing between virtual local networks (VLANs), and packet filtering.Don’t support workgroup access at this level.Avoid expanding the core when the internetwork grows (i.e., adding routers).

Week OneCisco Three Layer Hierarchical Model

The core layer must perform at peak level of efficiency and speed. If performance becomes an issue in the core, give preference to upgrades over expansion.

Week OneCore Layer Design Recommendations

Design the core for high reliability.Design for speed as a major

consideration.Select routing protocols with low

convergence times.

Week OneCisco Three Layer Hierarchical Model

The distribution layer is sometimes referred to as the workgroup layer and is the communication point between the access layer and the core. The premiary function of the distribution layer are to provide routing, filtering, and WAN access and to determine how packets can access the core.

Week OneCisco Three Layer Hierarchical ModelDistribution Recommendations:

Implement tools such as access lists, of packet filtering, and of queuing.Implementation of security and network policies, including address translation

and firewalls.Redistribution between routing

protocols, including static routing.Routing between VLANs and other

workgroup support functions

Week OneCisco Three Layer Hierarchical Model

Distribution Recommendations:Definitions of broadcast and multicast

domains.

Week OneCisco Three Layer Hierarchical Model

The access layer controls user and workgroup access to internetwork resources. The access layer is sometimes referred to as the desktop layer. The network resources most users will be available locally. Ethernet switching and static routing are frequently seen in the access layer.

Week OneNetwork TermsLogical address: IP addressPhysical address: MAC addressHub: Layer one (physical). No real intelligence.Switch: Layer two.Router: Layer three.Unicast transmission: One source to one

destination.Broadcast transmission: Distribute to all devices.Multicast transmission: Group of devices.

Week OneNetwork TermsARP protocol: What is my MAC address?RARP protocol: What is my logical address?Broadcast storms: Caused when there are

redundant paths.Spanning Tree Protocol (STP): Looks for loops on

the network.

Week OneNetwork Addresses:

Class A: 0 – 127Class B: 128 – 191Class C: 192 – 223Class D: multicastClass E: Research

Week OneSubnetting:Network address: 192.168.10.0

Dotted decimal notation: xxx.xxx.xxx.xxxDefault subnet: 255.255.255.0

nnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh Subnet mask: 255.255.255.192 or /26

nnnnnnnn.nnnnnnnn.nnnnnnnn.nnhhhhhhBinary representation (192.168.10.0):

11000000.10101000.00001010.00000000Binary representation (255.255.255.192):

11111111.11111111.11111111.11000000Least significant byte (192): .11000000

Week OneSubnetting

10000000 128 /2511000000 192 /2611100000 224 /2711110000 240 /2811111000 248 /2911111100 252 /3011111110 254 /31

Week OneQuestionsHow many subnets? How many hosts per subnet?What are the valid subnets?What is the broadcast address for each subnet?What are the valid hosts?