* Classless routing in a network. * Examples of classless routing protocols are RIPv2, OSPF, IS-IS, EIGRP and BGPv4. The following protocols support the VLSM (variable length subnet mask) and CIDR (Classless inter-domain routing protocol). Classless routing protocols send the subnet mask as well as the network address in the routing update. If I was working for an established or new company that needed a lot of hosts, I would choose classless because you can set the amount of hosts. Unlike classful routing where the amount of hosts are automatically set. For example if you have an IP address of 192.165.1.2 and you need 1024 hosts then your subnet mask would be 255.255.252.0/22 the slash 22 is the CIDR. This says that I borrowed 22 network bits to come up with 1024 hosts. IP classless routing is used to tell the router: To not drop any packet when the default route is configured. Which Means to use classless addressing that is not bound to a network class A, B or C used by Classful routing.

* SWITCHING IN ETHERNET (LAN’S) The most common used network is a local-area network (LAN). Ethernet is the most used and often shared-media of an LAN. Most if not all Apple computers and PCs come with 10/100 Ethernet ports for home use. The ports facilitate a user to create a small home bound network although connect to the Internet via a DSL. A 10/100 port means that the network interface supports both 10BASE-T at 10 megabits per second (Mbps) and 100BASE-T at 100 Mbps. In a public Ethernet environment, each device has to run for network bandwidth via the carrier sense multiple access with collision detect mechanism. In a switched Ethernet situation, each sender and/or receiver pair has the complete bandwidth available for use. Ethernet hubs which are used on layer 1 of the OSI model (physical layer) repeat only the physical signal a hub does not look at a source or destination address. Ethernet bridges and switches, used on layer 2 of the OSI (data link) look for and use the source and destination MAC address to build an interface table and to determine which piece or segment ought to receive the frame. Routers used on layer 3 of the OSI (network layer) use the network address to construct a routing table. A user or IT administrator should always consider and not forget about Ethernet switch Latency. Ethernet switch latency is when data enters a switch to the time it takes the data to leave the switch.

* HOW TO DESIGN A BASIC LOCAL AREA NETWORK (LAN)
In order to design a basic local network, first you have to know what a network is. A Network carries data in many types of environments, such as homes, small businesses, and large enterprises. In a large enterprise, a number of locations might need to communicate with each other, and you can describe those locations as follows. Might want to see or ask yourself or client what the network is being used for. How much security are you going to need? Is this for home and work use, are you going to need wireless. Approximately how many workers is the client going to have or how many computers are in the home.
If the network was going to be used for a corporation I would ask are we connecting to an existing domain. Meaning is this same in a different state or location. If I was adding or building onto an existing network. Say for instance my mom works for the VNA and she had surgery she had to work from home. So the IT administrator sent her home with a work laptop. But then she couldn’t log into the server, because he didn’t allow her access. You want to make sure when designing a LAN your design includes: * Functionality * Scalability * Adaptability * Manageability You also want to consider the following: * The function and placement of servers * Collision domain issues * Segmentation issues * Broadcast domains

* THE OPERATION OF THE SPANNING TREE PROTOCOL (STP)

The Spanning Tree Protocol (STP) is a link-management protocol that is part of the IEEE 802.1 standard for bridges and switches. The spanning-tree uses an algorithm that provides path redundancy in the network. STP prevents network loops created by multiple active paths between stations. Spanning tree example is like trying an alternate route to work because you’re android or GPS states it’s a faster more efficient route. However when you attempt it there is construction and detours everywhere. Now you are going in circles never making it to work. The same happens with data that attempt to communicate with a network port and doesn’t get a response. Then the data just continues to loop (Loops are when one or more route, exists between nodes in a network) until it gets a response. Establishing path redundancy, STP creates a tree spanning across all the switches in an extended network and forces redundant paths into a standby, or blocked, state. STP allows only one active path at a time between any two network devices, preventing loops, but establishes redundant links as a backup if the primary link fails. If a network piece becomes hard to find for whatever reason, the spanning-tree reconfigures the logical topology by reestablishing the link and activating the standby path. Without a spanning tree in place it is possible to have a traffic jam or flood the router.

* THE FUNCTION OF VIRTUAL LOCAL AREA NETWORKS (VLAN)
A VLAN spans one or more switches, which allows host devices to perform as if they are on the same network segment. A layer 3 device such as a router is required for traffic to move between VLANs. There are three major functions of VLAN’s 1. Limits the size of broadcast domains 2. Improves network performance 3. Provides a level of security
Example of a VLAN, imagine you own a small business. Within your business you need several different offices or departments all located in one building. Two years later, the business has expanded and, the network administrator wants to ensure that all the office computers share the same security features and bandwidth controls. The main building still houses the original network, as well as the human resources department. However the other departments have been placed randomly in the other building on other floors. Creating a large LAN and wiring each department together is possible but not all that simple when or if a problem happened. So it’s easier and more fault tolerant to cluster users and their computers by which department they work in. This process is called VLAN switching, which can be either used either with static or dynamic routing. When creating a VLAN you have to weigh all the options and see if you as the network administrator want to use VLAN trunking protocol (VTP) as an option

* COMMON VLAN TRUNKING PROTOCOLS (VTP) * VLAN Trunking Protocol (VTP) IS a simpler way for maintaining reliable VLAN configuration throughout a network.VTP is used to allocate and synchronize the identifying information about VLANs. VTP servers use trunk links to connect switches in the network. VTP is a Layer two (data-link) messaging protocol it allows VLAN configuration reliability throughout a common administrative domain. It does this by managing the additions, deletions, and name changes to the VLAN across the entire network. VTP minimizes accidents or faults with the configurations, such as duplicate VLAN names or incorrect VLAN-type. A machine operating as a VTP client cannot create, change, or delete VLANs. However a switch in CL mode will send VTP messages. Also a VTP CL does not save VLAN configurations in nonvolatile memory. VTP operates in one of three modes : A. Server mode B. Client mode C. Transparent mode
In VTP transparent mode a switch can create, delete, and modify VLANs, but the changes will not follow or be saved to other switches within the domain, only the local switch is affected. The default mode for VTP is server mode, however VLANs are not produced over any network until a management domain name is specified and trunking has been recognized. A Catalyst switch in service of VTP server mode will create, modify, and delete VLANs. As well as other configuration parameters for the entire VTP domain. VLAN configurations are saved in the Catalyst nonvolatile random-access in VTP server mode