Lecture 3-1 PDF: Campus Area Networks

Dr./ Ahmed Mohamed Rabie 1 2  A campus network is an enterprise network (hundreds or thousands of users) where we have one or more LANs in one or multiple buildings. Everything is geographically close to each other so we typically use Ethernet (and Wireless) for connectivity. T...

Dr./ Ahmed Mohamed Rabie 1 2  A campus network is an enterprise network (hundreds or thousands of users) where we have one or more LANs in one or multiple buildings. Everything is geographically close to each other so we typically use Ethernet (and Wireless) for connectivity. Typically the company owns everything on the campus hardware, cabling, etc. 3  A campus area network (CAN) is a computer network that spans a limited geographic area. CANs interconnect multiple local area networks (LAN) within an educational or corporate campus. Most CANs connect to the public Internet. CANs are smaller than metropolitan area networks (MAN) and wide area networks (WAN), which stretch over large geographic areas. 4 5  Typically, the organization that owns the campus also owns and operates all the networking equipment and infrastructure for the CAN. In contrast, MANs and WANs may combine infrastructure operated by several different providers. To support many users we require a lot of switch ports which means a lot of switches. We need a physical design to connect these switches to each other and also a good logical design to make it work. 6  There are several benefits of Campus Area Network (CAN), such as – Affordability: To construct CAN networks we use hardware devices like hub, switches, cables which are affordable. Easy accessibility of data: We can easily access the data that are present in different departments with the help of CAN. 7  Wireless medium: With the help of wireless connection we are able to link offices which are present in different buildings. Higher speed: CAN is supported to transfer large files or data with high speed over a network with the help of the internet. Protection: CAN networks have firewalls and proxy servers which are used for security purposes. Share internet connection: CAN network will share internet connection. 8  The disadvantages of CAN are as follows − It does not support a maximum number of nodes. It can connect only up to 64 nodes because of electrical loading. CAN maintenance is costly when compared to other networks like LAN, SAN,WAN etc. It can support up to 40 meter length. There are undesirable interactions in between all nodes. 9  Campus Area Network is used in different applications like as School Campus: CAN is used in the school campus for getting accessibility in different departments such as administrative office, hostel, libraries, athletic facilities, research labs, two different buildings etc. University Campus: CAN Network is also very useful in university to make connection with various departments and buildings as well. 10  Network Models 11 12 13  The Intelligent Information Network (IIN) offers companies an understanding of how the role of the network is evolving to meet business needs. The IIN vision is essentially the concept of network simplification through the alignment of technology and business priorities. Together these comprise the foundation of the IIN. 14  Marketing (Users) Services Infrastructure (Routing – Switching- Security- Wireless) IIN Network Model 15  The goal of the IIN is to build intelligence across multiple protocols and infrastructure layers to allow the network to be more aware of the needs of its users and respond efficiently to those needs by allocating needed resources and/or applications regardless of the nature of the connected device. The network aligns itself with the business priorities of an organization through services, availability, adaptivity, and resilience. 16  Campus Network Devices 17  1- Layer 1 Switching : A hub is a physical layer networking device which is used to connect multiple devices in a network. They are generally used to connect computers in a LAN. A hub has many ports in it. A computer which intends to be connected to the network is plugged in to one of these ports. When a data frame arrives at a port, it is broadcast to every other port, without considering whether it is destined for a particular destination or not. 18 19  All the devices connected to a hub are in a single collision and single broadcast domain. A collision occurs when two devices send a packet at the same time on the shared network segment. The packets collide and both devices must send the packets again, which reduces network efficiency. Collisions are often in a hub environment, because each port on a hub is in the same collision domain. 20  A broadcast domain is the domain in which a broadcast is forwarded. A broadcast domain contains all devices that can reach each other at the data link layer (by using broadcast. All ports on a hub by default in the same broadcast domain. 21  2- Layer 2 Switching : A layer 2 switch is a type of network switch or device that works on the data link layer and utilizes MAC Address to determine the path through where the frames are to be forwarded. It uses hardware based switching techniques to connect and transmit data. A layer 2 switch requires MAC address of NIC on each network node to transmit data. 22  Switch mainly performs these functions: Learning: The switch learns the MAC address of the device on the switch port on which it receives the frame. Forwarding: The switch does 2 types of message forwarding : (a) Unicast: The switch unicasts the frame to the destination only when it has an entry for destination MAC address in its MAC address table. 23  (b) Unknown Unicast: When a switch receives a unicast frame for a destination for which the switch has no entry in its MAC table then the switch simply broadcasts the frame through all ports (except for the one from which it was received). This is known as flooding. Flooding causes in switch when frame send from unknown mac address, multicast, and broadcast. VLANs is suitable for controlling flooding technique. 24 25  Filtering: The frame will be forwarded through that switch port only for which the switch has already learned the MAC address in its MAC table. Loop avoidance (Listening): For redundancy, two switches are connected to each other through two links which can also result in layer 2 loops. These loops are avoided by switching by using the STP(Spanning tree protocol) protocol. 26  Every port on a switch is in a different collision domain, i.e. a switch is a collision domain separator. So messages that come from devices connected to different ports never experience a collision. This helps us during designing networks but there is still a problem with switches. They never break broadcast domains, which means it is not a broadcast domain separator. All the ports on the switch are still in a single broadcast domain. If a device sends a broadcast message, it will still cause congestion. 27  Microsegmentation refers to the process of segmenting a collision domain into various segments. Microsegmentation is mainly used to enhance the efficiency or security of the network. The microsegmentation performed by the switch results in the reduction of collision domains. Only two nodes will be present as a result of the collision domain reduction. 28  Microsegmentation is a phenomenon in the direction of fewer users per segment. Micro-segmentation enables the creation of dedicated or private segments, i.e., one user per segment. The key advantage of microsegmentation is that it lets every node gain access to the entire bandwidth available in the transmission channel rather than sharing the bandwidth with others. 29  So, there is no need for them to content with other users for the available bandwidth. Due to this fact, the chance for collisions to occur is cut down tremendously, particularly in a full-duplex mode, where concurrent transmissions in both directions are enabled. When a network switch interface receives more traffic than it can process, it either buffers or drops the traffic. Buffering is generally caused by interface speed differences, traffic bursts and many-to-one traffic patterns. The most common cause of switch buffer is some variation of the many-to-one traffic pattern. 30 31  Layer 2 Switching Methods: LAN switches are characterized by the forwarding method that they support, such as a store-and- forward switch, cut-through switch, or fragment-free switch. In the store-and-forward switching method, error checking is performed against the frame, and any frame with errors is discarded. With the cut-through switching method, no error checking is performed against the frame, which makes forwarding the frame through the switch faster than store-and-forward switches. 32  1- Store and forward switching : In this switching technique, when the switch receives the frame, it stores the frame data in buffers until the full frame has been received. During the this process, the switch analyses the current frame for information about its destination. This switching technique is required for Quality of Service (QoS) analysis on converged networks where the classification of the frame for traffic prioritization is necessary. For example, VoIP data streams need to have high priority over other kind of traffic. 33 34  2. Cut-through switching : In this switching technique, the switch acts upon the data as soon as it is received, even if the full frame is not received (transmission is not complete). The switch buffers is enough of the frame to read the destination MAC address so that it can find the port where it supposed to send the data. The switch takes the destination MAC address from switching table, determines the outgoing interface port, and forwards the frame onto its destination through the designated switch port. This switching technique does not involve any error check process by the switch. 35 36  3- Fragment-free switching: In this switching technique there is a trade-off between the high latency – high integrity of store and forward switching and the low latency – reduced integrity of fast-forward switching. The switch stores and perform a small error check on the first 64 bytes of the frame before forwarding. This switching technique includes the concept of store and forward switching and fast-forward switching. This switching technique only stores the first 64 bytes of the frame because the most network errors and collisions occur during the first 64 bytes and tries to enhance fast-forward switching by doing a small error check to ensure that a collision has not occurred before forwarding the frame. 37 38