Week Two Agenda Announcements Review previous week information Current week information Discuss 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.
Review Week One Internetworking Terminology 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 One Internetworking 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
Review Week One Internetworking Terminology 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.
Review Week One Internetworking Terminology 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.
Review Week One Internetworking Terminology 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.
Review Week One Internetworking Terminology RoutingProtocol are used to update routing tables between routing tables. Example of routing protocols: RIP, EIGRP, and OSPF. Network addresses are protocol specific network addresses (22.214.171.124). 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.
Review Week One Internetworking Terminology 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.
Review Week One Internetworking Terminology 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
Review Week One Internetworking Terminology 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.
Review Week One Internetworking Terminology Logical address: IP address Physical address: MAC address Hub: 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 One Layered 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 One Layered 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.
Review Week One OSI 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.
Review Week One OSI Model The bottom four layers define how data is transmitted end-to-end. Transportprovides 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.
Review Week One OSI Model Application - File, print, message, database, and application Presentation – Data encryption, compression, and translation services Session – Dialog control Transport – End-to-end connection (connection-oriented) Network – Routing Data Link - Framing Physical – Physical topology
Review Week One OSI Model 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.
Review Week One OSI 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, until completion, then a call termination takes place to tear down the virtual circuit.
Review Week One TCP/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 Model Host-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 Model Internet 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 One Ethernet 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).
Review Week One Ethernet Networking 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.
Review Week One Ethernet Networking 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.
Review Week One Ethernet Networking 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?
Review Week One Ethernet Networking 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 One Half- 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 One Full-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 One Half- 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 One Ethernet 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 One Ethernet 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 One Ethernet Cabling Straight-Through Cable This 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 Cable This type of Ethernet cable is used to connect: Switch to switch (h/s <--> h/s) Hub to hub Host to host
Review Week One Ethernet Cabling Rolled 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 One Data 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 One Data Encapsulation Application Presentation Session Transport – PDU (Segment) TCP header/Data Network – PDU (Packet) IP header/Data Data Link – PDU (Frame) LLC header/Data/FCS MAC header/Data/FCS Physical – PDU (Bits) 0101110101010101
Review Week One Serial 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 One Routing Protocols Administrative distance (AD): Used to rate the trustworthiness of routing information received on a router from a neighboring router Route SourceDefault AD Connected interface 0 Static route 1 EIGRP (Cisco) 90 IGRP (Cisco) 100 OSPF 110 RIP 120 External EIGRP 170
Review Week One Cisco 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 Layer Distribution Layer Access Layer
Review Week One Cisco 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.
Review Week One Cisco 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. 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).
Review Week One Cisco 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.