1.2 Quality of Service (QoS) and Bandwidth Management
Quality of Service (QoS) is defined in several ways. QoS is a set of methods to oversee committed transmission capacity, deferral, jitter, and bundles misfortune for streams in a system. The motivation behind every QoS instrument is to impact no less than one of these four attributes and, now and again, each of the four of these.
The main reasons that can affect QoS are:
In an IP network, latency is defined as the time taken for a packet to enter and leave the network. As shown in Figure packet A enters the network at time = t0 and leaves the network at time = t1. The latency of the network, t2, for packet A, in this case, is t1 t0.
Figure 3: Network Latency Diagram
Note that latency is an end-to-end measurement of network delay. The time, t2, is the total delay introduced from various components of the network. These include transmission technology used, the speed at which packets can be forwarded at each intermediate node, and the various transmission speeds along the way.
Jitter is affected by the traffic condition in the network. As a video packet traverses the network, it has to contend with packets from other applications along the way (for example, FTP and web applications). The latter two applications have a very different characteristic from that of the video: They are bursty by nature and may transmit variable-sized packets. The network needs to ensure that the jitter for the voice and video is not affected by these applications. This is when QoS is required.
Besides solving latency and jitter issues, preventing packet loss in applications such as voice and video is critical. Although losing one packet once every great while might not adversely effect these applications, losing too many might produce undesirable results. A long silence might interrupt a conversation, or a video screen might appear blank. In the case of the bank doing surveillance using an IP camera, losing images might have serious consequences.
Packet loss also results from the traffic condition in the network. A converged network carries different application types of data, video, and voice. These different applications must contend for the resources in the network. If the network is congested, packets are dropped because no resources are available. The network must be able to prevent the loss of packets that belong to voice and video applications. This is an area QoS can help in mitigating the risk of packet loss.
(“Zippy” Grigonis, 2015)
Below examples for QOS:
Dot.edu College has a security policy in place, it can begin to apply the document and its rules to their particular environment. Dot.edu College with truly comprehensive security policies find that what they have created is a road map that helps them implement the correct security appliances, mechanisms, and controls that satisfy their particular security needs. Dot.edu College will also quickly begin to find the weaknesses in their security posture through the process of identifying important resources and associated policies and tying that information to current inadequate security controls. This documentation is sure to change over time as the computing and physical environments change, which should be expected and accepted as normal security policy maintenance. The underlying network provides an perfect place to implement core and advanced security solutions.
Scalability point of view network is setup in this manner so that we do IOS up gradation of switch without any outage and downtime or other word it can refer to the ability of a system to increase its total output under an improved load when resources are added. For instance we are using UTP cat 3 cable and now we need to upgrade it to UTP cat 6 cable.
It is signified as a percentage of period. How many days, hours, and minutes is the server electrical infrastructure operational and supplying power over a given time period? Server availability suffers whenever the electrical infrastructure fails to provide power to the room.
Most companies want extremely high availability for their server , because downtime affects their ability to be productive and perform business functions. How high, though, can vary significantly and is represented by the concept of nines. The more nines of availability, the closer to 100% up time a system or device has reached. For example, that your company brings the DC electrical system offline for one hour of maintenance every month. Assuming there are no additional outages of any kind, that means that the DC is running for all but 12 of the 8760 hours in the year. That’s 99.863% of the time, or two nines of availability.
(Van Lengen, 2015)
Common challenges faced by the network designer are as listed below:
Below are some of techniques which can be used to make a LAN secure:
A traditional hierarchical LAN design has three layers:
Each layer of hierarchical model work independently that increase scalability for ex. In college library we have required some network device connection. You can connect one uplink port to another switch on library and after according to requirement we can connect device through new switches. We can expand over network according to over requirement.