Week Two Agenda

Week Two AgendaAnnouncementsReview previous week informationCurrent week informationDiscuss lab assignment

Review Week One Internetworking Terminology

Network segmentation is the breaking up of a large network into smaller networks. Routers, switches, and bridges are used to create network segmentation.Router is used to connect networks together and route packets of data from one network to another. By default, they break up broadcast domains.


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.

Bridge 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.

Review Week One Internetwork Devices

A hub is really a multiple port device found at the Physical layer.

A repeater receives a digital signal and re-amplifies or regenerates that signal. Then forwards the digital signal out all active ports without looking at any data. Physical layer function

Review Week One Internetwork Devices

The switches and bridges work at the Data Link layer and filter the network using hardware (MAC) addresses.

Review Week OneInternetworking Terminology

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. Provide example

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. Provide example


Flow control is implemented at the transport layer to prevent the receiving host buffers from being overflowed by the send host.

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.


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.

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.

Routed Protocols (such as IP and IPX) are used to transmit user data through an internetwork.


Routing Protocol are used to update routing tables between routing tables. Example of routing protocols: RIP, EIGRP, and OSPF.

Network addresses are protocol specific network addresses (192.160.18.0). 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 designated for a specific network.


The Media Access Control (MAC) defines how 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.

Logical Link Control (LLC) is a sub-layer 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.


An IP address is a software address assigned to each machine on an IP network. It designates the specific location of a device on the network.

A MAC address is hard-coded on a network interface card (NIC) and is used to locate hosts on a local network. The MAC address is a 48 bit (6byte) address written in a hexadecimal format. MAC format: Organizationally Unique Identifier

I/G I/G OUI Vendor assigned


ARP protocol requests what is my MAC address?

RARP protocol requests what is my logical address (IP)?

Broadcast storms are caused when there are redundant paths.

Spanning Tree Protocol (STP) looks for loops on the network. STP’s job is to find all links in the network and shut down any redundant ones, thereby preventing network loops from occurring.


Logical 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.

Review Week OneLayered Approach

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.

Review Week OneLayered Approach1. Advantages of using the OSI layered model

are:2. Allows multiple-vendor development through

standardization of network components.3. Allows various types of network hardware

and software to communicate.4. Allows changes in one layer from affecting

other layers, so it doesn’t hamper development.

Review Week OneOSI Model

The top three layers define how the applications within the end stations will communicate with each other and with users. Application provides a user interface.Presentation presents data and handles encryption.Session keeps different applications data separate.


The bottom four layers define how data is transmitted end-to-end.Transport provides reliable or unreliable delivery.Network provides logical addressing.Data Link provides access to media using MAC address.Physical moves bits between devices, specifies voltage, wire speed, and pin-out of cables.


Application - File, print, message, database, and applicationPresentation – Data encryption, compression, and translation servicesSession – Dialog controlTransport – End-to-end connection (connection-oriented)Network – Routing Data Link - FramingPhysical – Physical topology


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.


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, until completion, then a call termination takes place to tear down the virtual circuit.

Review Week OneTCP/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.

Review Week One

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.

Review Week One

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.

Review Week One

• The four layers of the TCP/IP architecture can be compared to certain levels of the OSI model. It’s important to know what each level of the TCP/IP protocol architecture does, and how these layers map to the OSI model.

• The Application Layer of the TCP/IP model performs much the same tasks as the Application, Presentation, and Session layers of the OSI model.

Review Week One• The Transport layer in the TCP/IP architecture

is similar to the Transport layer in the OSI model. This layer can use TCP or UDP as well.

• The Internetwork layer in the TCP/IP architecture uses IP addresses to determine how packets should be routed. Remember that the OSI model uses IP addresses, or “Layer 3 Addresses”, at the Network layer. The two layers do much the same thing. This layer is also referred to in the TCP/IP model as the Internet layer.

Review Week One

• The Network Interface layer in the TCP/IP architecture serves to define the protocols and the hardware needed to actually deliver the data across the network. The Network Interface model does the work of both the Data Link and Physical Layers in the OSI model.

Review Week OneEthernet 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 Fast Ethernet and Gigabit Ethernet, into an existing network infrastructure.Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD).


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.


Carrier Sense Multiple Access/Collision Detection (CSMA/CD)The LAN access method used in Ethernet. When a device wants to gain access to the network, it checks to see if the network is quiet (senses the carrier). If it is not, it waits a random amount of time before retrying. If the network is quiet and two devices access the line at exactly the same time, their signals collide.


When the collision is detected, they both back off and each wait a random amount of time before retrying.

What is the difference between CSMA/CD and CSMA/CA?


What is the difference between CSMA/CD and CSMA/CA?

• CSMA/CA: it is also similar to CSMA but the only difference is that it is used for the wireless media i.e. 802.11; where the computer nodes are hidden.

Review Week OneHalf- Duplex Ethernet

Half duplex uses only one wire pair with a signal running in both directions on the wire.Half duplex Ethernet typically 10BaseT.It uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur.

Review Week OneFull-Duplex Ethernet

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.

Review Week OneHalf- and Full-Duplex Ethernet

Typical speeds are 10Mbps, 100Mbps, and 200Mbps for Fast Ethernet. Full-duplex Ethernet can be used in three situations:

Review Week OneEthernet at the Data Link Layer

Ethernet 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.

Review Week OneEthernet 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 (Fast Ethernet) and 802.3Z (Gigabit Ethernet).

Review Week OneEthernet 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

Review Week OneEthernet CablingRolled Cable

A rolled Ethernet cable can be used to connect a host to a router console serial communication (com) port.(host <--> Router/Switch)When preparing design drawings, you should specify the types of cables used between one device and another.

Review Week OneData 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.

Review Week OneData Encapsulation

Application Presentation Session Transport – PDU (Segment) TCP header/DataNetwork – PDU (Packet) IP header/DataData Link – PDU (Frame)

LLC header/Data/FCSMAC header/Data/FCS

Physical – PDU (Bits) 0101110101010101

Review Week OneSerial 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.

Review Week OneRouting Protocols

Administrative distance (AD): Used to rate the trustworthiness of routing information received on a router from a neighboring router

Route Source Default ADConnected interface 0Static route 1EIGRP (Cisco) 90IGRP (Cisco) 100OSPF 110RIP 120External EIGRP 170

Review Week OneCisco Three Layer Hierarchical Model

A 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


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.


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.Don’t anything to slow down traffic. This includes adding access lists, 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).


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.

Review 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.


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

Review 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


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.

Review Week One

Review Week OneNetwork Addresses:

Class A: 0 – 127 0xxxxxxxClass B: 128 – 191 10xxxxxxClass C: 192 – 223 110xxxxxClass D: Multicast (224 – 239)Class E: Research (240 – 255)What happens if you have a large network address and create four networks from it? You perform subnetting, because it allows you to take a large network and break down into smaller ones.

Review Week OneSub netting: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

Review Week OneSub netting

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

Review Week OneSubnet Questions

How 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?

Week TwoInternetworking Terminology

Packet-switched networks is one based on the transmission of data packets. Dividing a continuous stream of data into small units called packets, enables data from multiple devices on a network to share the same communications channel simultaneously, but requires precise routing information. Packet switch is a physical device that makes it possible for a communication channel to share several connections, its functions include finding the most efficient transmission path for packets.


Leased lines are permanent connection between two points leased from the telephone company.Circuit-switched network is used with dial-up networks such as PPP and ISDN. Passes data, but needs to set up the connection first, similar to making a phone call.


DSL is a high-bandwidth connection over the traditional copper telephone lines. DSL utilizes modems at either end of the wire. It is another technology that enables SPs to deliver a wide range of services to their customers.


Convergence this is the process for all routers in an internetwork to update their routing tables and create a consistent view of the network, using the best possible path. No user data is passed during a convergence time.Latency is the time it takes a data packet to get from one location to another.Cable is a high-speed copper platform that supports analog and digital video services over coaxial cables.


Internet Control Message Protocol (ICMP) is used by IP for many different services. ICMP is a management protocol and messaging service provider for IP. Its messages are carried as IP datagram's. If a router receives a packet destined for a network that the router doesn’t know about, it will send an ICMP Destination Unreachable messages back to the sender station.


If a routers memory buffer for receiving an incoming datagram is full, ICMP messages are sent out.Each IP datagram is allotted a certain number of routers, called hops, that it may go through.An ICMP message is sent to the sending station informing them that the packet was dropped.The ping command uses ICMP echo messages to check the physical connectivity of machines on an internetwork.


Flood (Broadcast and multicast frames). Learning

Week TwoReasons Requiring Redesign

If troubleshooting network problems becomes too frequent or even impossible to manage.

Week TwoCisco Vision of Intelligent Networks

Network architecture exists today largely because there is an enormous variety of network application-level business solutions and a constant need to integrate applications into a new architecture. Cisco’s vision and infrastructure enables customers to build a more intelligent network infrastructure. The Cisco Service Oriented Network Architecture (SONA) focuses on service and applications rather than a traffic transport-oriented view.

Week TwoCisco Vision of Intelligent Networks

Integrating networked resources and information that have been largely separate entities.Sharing intelligence across multiple products and infrastructure layers.Full network component participation in the delivery of services and applications.

Week TwoEvolving to an Intelligent Information Network

Phase 1: Integrated transport is to consolidate all services (data, voice, and video) into an IP network for secure network convergence.

Phase 2: Integrate Services when the network infrastructure is converged, IT resources can be pooled and shared, or virtualized, to flexibly address the organization’s changing needs.

Week TwoEvolving to an Intelligent Information Network

Phase 3: Integrated application is where focus to the network application-aware so that it can optimize application performance and more efficiently deliver networked applications to users.

Week TwoSONA Framework

Networked Infrastructure layer: This layer insures that all IT resources interconnect across a converged network foundation. The objective is to provide connectivity, anywhere and anytime.Interactive Services layer: This layer includes both application networking services and infrastructure services. This will enable efficient allocation of resources to applications and business processes delivered through the network infrastructure.


Application layer: Includes business applications and collaboration applications. The objective of this layer is to meet business requirements and achieve efficiencies by leveraging the Interactive Services layer.

Week Two

Week TwoSONA FrameworkWhat are the benefits?

Functionality: Supports the organizational requirements.Scalability: Supports growth and expansion of organizational tasks by separating functions and products into layers.Availability: Provides the necessary services, reliability, anywhere, anytime.


Performance: Provides the desired responsiveness, throughput, and utilization on a per application basis through the network infrastructure and services.Manageability: Provides control, performance monitoring, fault detection.


Efficiency: Provides the required network services and infrastructure with reasonable operational costs and appropriate capital investment on a migration path to a more intelligent network, through step-by-step network services growth.Security: Provides for an effective balance between usability and security while protecting information assets and infrastructure from inside and outside users.

Week TwoPPDIOO Network Lifecycle

Prepare phase: The network is built.Plan phase: A network design specification is produced.Design phase: Includes fault detection and correction and performance monitoring.Implement phase: Network requirements are identified.Operate phase: Business requirements and strategy related to the network are established.

Week TwoPPDIOO Network Lifecycle

Optimize phase: Based on proactive management of the network.

Week TwoDesign Methodology

Step 1: Identify your customer requirements.Step 2: Characterize the existing network and

sites.Step 3: Design the network topology and solutions, which includes the following:

Possibly building a pilot or prototype network.

Creating a detailed design document.

Week TwoDesign Mythology1. Planned application and network services.2. Organizational goals.3. Technical goals.4. Technical constraints.

Week TwoTypical Organizational Design Constraints

BudgetTime frame for window of opportunity

Availability of personnelExperiencedTrainable

PoliciesSchedule

TimelineNew applications

Week TwoTypical Organizational Goals1. Increase revenue2. Shorter development cycles3. Improved customer support4. Open the organization’s information

infrastructure

Week TwoDetermining Factors Affecting the Scope of the

Design Project1. Is the design for a new network or is a

modification of an existing network?2. Is the design for an entire enterprise network,

a subset of the network, or simply a single segment or module?

3. Does the design address a single function or the entire network’s functionality?

4. What OSI protocol layers are involved.

Week TwoNew Application Schedule

New network designs often are driven by the introduction of new network applications. The implementation time frame for new applications are often tightly connected and influence the availability time for network design.

Week TwoEvaluate Capacities

If parts of the network provide insufficient bandwidth and cannot be increased because of technical reasons, the situation must be resolved by implementing other means.Traffic analysis provides helpful information about applications and protocols used in the network and might reveal any shortcoming in the network.Audits can be useful in revealing marginal situations that might require temporary changes to the network.

Week TwoEvaluate Capacities

A saturated Ethernet segment occurs at 40 percent network utilization.A WAN link saturates at about 70 percent network utilization.Network characterization can be a lengthy process. Factors to consider are the size of the network, and complexity, the experience of the network engineer, the quality of the documentation and communication, the efficiency of the tools.

Week TwoDesign Methodology

Use a design document to list and identify the network. Categories are as follows:

IntroductionDesign requirementsExisting network infrastructureDesignProof of ConceptImplementation planAppendixes

Week TwoImplementation Process

Step 1: Plan the implementation.Step 2: Implement and verify the design.Step 3: Monitor and optionally redesign.

Week TwoNetwork Design Tools

A pilot network: Tests and verifies the design before the network is implemented to the real world. Could be a subset of the existing network.A prototype network: Tests and verifies a redesign in an isolated network before it is applied to the existing network.


Top-Down Approach can be used to design a network solution, after the organizational requirements and documenting the existing network. This approach allows the designer to view the picture before worrying about the details.Botton-up Approach has a limited usage. If the network is small or if the network is faced with a critical situation, should this approach be used.


Decision tables or truth tables are used to make systematic decisions when there are multiple choices. Decision tables facilitate the selection of a certain choice from many choices and can provide helpful justification why a certain solution was chosen. Simulation and verification tools and services.

Week TwoDesign Verification

The network designer should be involved in the implementation phase to assist in the design verification and take corrective action if necessary. He/she should be available after the implementation phase for a period of time to answer questions and provide training for those performing network support.Documentation should be in a central location and maintained to provide reliable information for new personnel.

Week TwoSite Contact Information

Site location, name, address, and shipping addressSite contact’s name and all the possible ways to reach that person (phone, cell phone, pager, and e-mail address).Site ownerHours of operationAccess procedures, including those for security, safety, and union labor.Specific location of equipment.

Week TwoAssignmentsAssignment 1-3 Concept Question #1 due May

2, 2011Good example to review before starting project.Case Study: Read ACMC Hospital Network

Upgrade, page 121. Answers Appendix A.

Week Two Agenda

Documents

agenda week

remote network

network area

large network

different routing protocols

example of routing protocols

specific network addresses

individual routing protocols