Besides connecting the arioso network segments, the backbone may have its own devices that can be accessed by other network segments Metropolitan area network (MAN): MAN spans a city and is Often used to connect remote BANS. MAN in some cases can be considered a citywide BAN and as the geographic distances they cover have increased, especially With the use Of fiber-optics. BANS connect networks between floors off building, across a city, or between states and countries. BAN and MAN are sometimes used interchangeably, based on the scope of the BAN.
Network Segments: Each individual LANA owned by an organization is referred to as a outwork segment. Horizontal Segment: A moderate. To large-scale organization might have a network segment on each floor off multistory building, Because each nonvoter segment, or CAN, typically occupies its own floor, this type of network segment is often referred to as a horizontal network, For example, assume that a business occupies three floors tot a building. On each floor is a separate CAN, or horizontal network segment Vertical Network: Lana could, and probably would, be connected to each other by a BAN.
This type tot multi-tool connection is an example off vertical network. The BAN in this instance is the central connecting cable running vertically from floor to floor that enables the horizontal networks to communicate with each other, part of configuration analysis includes determining how each network segment connects to the BAN. Generally, each network segment is connected to the BAN using either a switch or a router. Deciding which Backbone Protocol to use? Questions to ask: 1) Traffic Demands 2) Constant Communication 3) Mostly Independent Gigabyte Ethernet: is a very popular choice for Bans.
The Siege’s initial standard for Gigabit Ethernet is the 802. 2 standard. Gigabit Ethernet allows for a data rate Of 1 ,OHO Mbps, or 1 Gaps. A major advantage of all of the officially recognized forms of Gigabit Ethernet is that each form builds on the standards of the preexisting Ethernet protocol, This means that the MAC layer and access method for Gigabit Ethernet are the same as those for standard and Fast Ethernet. Additionally, Gigabit Ethernet supports both half- and full-duplex communications. Other protocols that might be used for a backbone include Frame Relay (FRR) and Asynchronous Transfer Mode (ATM).
Frame Relay and ATM are also frequently associated with WANTS. As such, discussion tot Frame Relay and ATM will be reserved for Chapter 7, which focuses on WANTS Backbone Architecture: two most common BAN architectures are distributed and collapsed. Factors that influence a business’s decision as to which architecture to use include business needs, the condition of the physical facility (sometimes called the plant or campus), how users need to communicate, and the budget. The larger and more complex the organization, the more critical the decision becomes as to what type of backbone architecture to use.
It can be very costly to change an existing backbone architecture once one has been put in place. Distributed Backbone: runs throughout the entire enterprise. This type of backbone uses a central cable to which the network segments are connected. The central cable, Which is the backbone, requires its own protocol, such as Gigabit Ethernet; it is also its own network. The backbone is considered to be distributed because each network segment has its own cabled connection to the backbone. The backbone is distributed to the Lana by connecting the Lana to the backbone.
They maybe connected with routers and switches. In some cases even servers. A distributed backbone typically has separate routers that connect each logical network to the backbone. Because separate routers are used, intervention traffic may have to pass through several routers to reach its destination. One advantage of a distributed backbone is that it allows resources required by most, if not all, intertwining users to be placed directly on the BAN. Collapsed Backbone: connects all of the Nortek segments to a central, single router or switch.
This central device is, in effect, the backbone, The network segments typically once to the central backbone device by means of a hub, switch, or router. Because only a single,central backbone device is used, cabling is greatly reduced. Furthermore, additional connecting devices are not required. A collapsed backbone can result in significant cost savings. Backplane: is an internal, high-speed communications bus that is used in place of the connecting cables found in a distributed backbone Because fiber-optic cabling is used to connect network segments to the collapsed backbone’s backplane, long distances are possible.
With fiber-optic cabling, network segments may be widely scattered cross a building or even a campus. Backbone Fault Tolerance: is the capability of a technology to recover in the event of error, failure, or some other unexpected event that disrupts organizational communications and functions. Should the backbone fail for Some reason, intertwining may no longer be possible. In such an event, business could come to a standstill and, depending on the recovery time, irreparable damage may occur. However, if fault tolerance has been built into the backbone, intertwining will likely still be possible.
Fault tolerance Will determine its ability to survive an error, damage, r some other unforeseen circumstance. Redundant Backbone: Should one backbone become unavailable, the other can still be used for intertwining traffic. Furthermore, using a redundant backbone also allows for the load balancing of intertwining traffic. Placing half of the network segments on each backbone, intertwining traffic is shared, or balanced, across the backbones, resulting in improved communications performance. It is also VERY expensive. Wiring Closet: The patch panel is usually housed in the wiring closet.
The wiring closet may also contain servers that provide resources across he enterprise. In a multiform design, wiring closets are usually placed one above the other. Placing the wiring closets in vertical alignment greatly facilitates their connection. Data Center: usually moderately to largely spaced and house all of the necessary networking equipment for the entire enterprise in a central location. As with wiring closets, data centers should be tightly secured and environmentally appropriate for the equipment they house. The data center may contain routers, switches, servers, and even .NET. Org segment hubs that connect individual devices to their network segment. Rack: Hubs, Servers, Switches, Routers are bolted to them. Packet Errors: Related to Early Collisions and Late Collisions Early Collisions: Collisions in an Ethernet network are to be expected, and the collisions themselves are not a problem. However, when too many collisions occur, say, 5 percent or more of the total packets, then corrective measures are needed. If this happens too Often, the segment network may have to be split. Late Collisions: can be caused by excessive cable lengths. Another potential cause is the use of too many repeaters.
Late collisions can result in lost packets that require retransmission by higher-level protocols. Runts: Too small of a packet, may result from a defective NICE. They are also caused when a transmitting device stops transmission in the middle of a packet due to the detection of a collision. Runts can never be entirely eliminated, because they result from normal collisions, hut when the number of runts is greater than the monitored number of collisions, a problem is indicated, may be caused by a defective N I C, Giants: Too large of a packet, and usually caused by a jabbering NICE.
Jabbering: NICE is one that is transmitting continuously and incorrectly. Unlike runts, giants are not the result of a normal Ethernet operation, and therefore indicate a definite problem. Whereas a bad NICE is the mostly likely cause of a giant, another hardware device may also be faulty or a cable segment may be defective. If a NICE or cable segment is found to be the cause of the problem, the best solution is to remove and discard the failing component and replace it with a new one. Broadcast Storm: When the total broadcast traffic reaches or exceeds a rate of 126 packets per second, a broadcast storm results.
The major problem with such a storm is that it is self-sustaining resulting in a flood of garbage packets that eventually consume all network bandwidth, preventing any other valid communications from occurring. SMS (Switched Multipliable Data Services): supports the exchange Of data between Lana in different parts of a city or between network segments over a large campus. SMS is a packet-switched datagram service for high-speed MAN traffic. SMILE (Switched Multipliable Data Services Interface Protocol): provides for three layers Of protocols that define user information frame structuring, dressing, error control, and overall transport.
