Ring topology. Network topologies

Casting network has many names: cape, cape, mantle, cover, parachute . Oddly enough, fans of casting net fishing and especially specialists in this fishing are quite rare in our country. There are many reasons for this. Historically, for a long time, fishing with a cast net was traditional way fisheries in mainly southern countries (South America, Asia). Fishermen in those parts have been doing this kind of fishing since childhood and achieve amazing results.

Tourists watch in amazement as a native fisherman throws an incomprehensible package far away, which on the fly unfolds into a large round net, which soon returns from the muddy waters with a rich catch. Amazement gave way to a completely legitimate desire: we want to fish the same way! As a result, the casting network quickly began to conquer non-traditional countries.

The fishing principle is as follows: the net is assembled on the hand in a certain way (so that it can easily unfold in flight), then it is thrown horizontally onto the water and covers an area of ​​​​water corresponding to the diameter of the opened net. After the loaded part of the net sinks to the bottom, the net is pulled out by the cord attached to the base. It is possible to catch fish in the water column without lowering the gear to the bottom, but this requires a net of a slightly modified design.

Casting network (American type) example

Casting networks are divided into two large groups: American type and Spanish. The American type is more convenient when casting, more catchy and easier to make with your own hands. The Spanish type has one advantage: in places with underwater terrain that is inconvenient for fishing, it is less likely to get caught on stones, driftwood, etc.

The casting net is a network fabric in the shape of a regular circle, along the edge of which a cord is sewn, equipped with very often set lead weights. To pull the net, use a central braided cord (twisted cord is not suitable in any case), thick enough (so as not to cut your hands when quickly retrieving the tackle), usually at least 5–6 mm. Its standard length is 4–4.5 m, but many amateurs, having mastered the tackle perfectly, increase the length of the cord by 1.5–2 times. At the end of the cord there is a loop with a diameter of 20–25 cm.

In American networks, the other end of the central cord is attached to numerous slings (veins) stretched to the cargo cord; in Spanish networks, it is attached to the central part of the network. This constructive difference determines and various jobs network after casting.

When pulling out an American-type tackle, the central cord, with the help of veins, pulls the weight cord to the center and practically collects it together into a compact lump, thereby tightening the net and forming a bag with closed exit. When pulling out a Spanish-type net, the sinkers converge towards the center under the influence of the cord's pull and their own gravity, closing the exit, and the catch remains in the pockets of the net located along its perimeter.

On American gear, in the very center of the net there is a small round hole (5–6 cm in diameter), and the net fabric along its edge is attached to a plastic or fluoroplastic sleeve. One hole is drilled in the sleeve (for the smallest nets) or several (6–8 cm for the largest ones), through which the vein slings slide.

The net fabric (with fairly small meshes, from 9 to 15 mm) is taken from both monofilament and twisted thread.

Tips for making an American-style casting net

If someone wants to make an American-style casting net with their own hands, they should follow several rules:

1. Lead sinkers are placed on the load cord evenly and very often, with a distance between their centers of no more than 10–12 cm. The weight of the sinkers is from 20 to 35 g, depending on the size of the net; their shape is a highly elongated cylinder; spherical loads, especially those capable of falling into a network cell, are not applicable. If you do not use purchased sinkers, but cast them yourself, you must carefully process each one, eliminating all irregularities and casting defects.
2. Veins (slings) are made of fishing line (monofilament, braided makes fishing difficult) with a thickness of 1 mm or more, their length is not much greater than the radius of the tackle. The veins are attached to the load cord quite often, at least every 0.5 m, and accordingly, their number increases with the size of the gear. If not one, but several holes are drilled in a plastic sleeve, then through each one it is necessary to pass those veins that lead to the corresponding edge of the network, avoiding crossing. Sharp edges on the edges of holes, any irregularities and burrs are unacceptable.
3. The knot that brings the veins together is made as compact and neat as possible, without the tails of the fishing line sticking out to the side. Since there is a torque when casting, it is better to connect it to the central pulling cord through a swivel of sufficient strength. Sometimes a plastic disk with a diameter of 3–4 cm with holes along the edge (according to the number of veins) is placed in front of the knot, and each vein is passed into its own hole.

DIY casting network video:

What size net should I start learning casting with?

A question that does not have a clear answer. On the one hand, the smaller the radius of the net, the easier it is to cast, and the learning stage goes much faster. However, having perfectly mastered casting a three-foot net (mostly suitable for catching live bait), it is quite difficult to retrain for larger gear. Much depends on physical parameters fisherman: the higher his height and longer than an arm, the easier it will be to learn how to cast a large net.

I advise you to first decide: why, exactly, do you need a casting network? For those who like to catch predators with live bait, a casting net is an indispensable auxiliary tool. IN in every sense irreplaceable: never when catching live bait with a fishing rod or a small fish of any other design will you start catching predators as quickly after arriving at the reservoir as if you had a compact casting net in your backpack, ready for immediate use. You can start hunting for pike or pike perch faster by only bringing live bait with you, which is not always convenient.

So if you plan to use a casting net only as a bait fish, buy an easy-to-learn three-foot net, and the problem with live bait will disappear forever. In addition, as a bonus, sometimes (especially in muddy water or when casting at night) you can hook a large fish. But if it is assumed that the casting net will become the main fishing tool for quite large fish, then it is better to start mastering the tackle with a net with a radius of at least 1.7–2 m. It will, of course, take longer to learn how to cast, but then switching to even a ten-foot net will not be a problem will make up.

Casting technique

The figure shows the casting phases for both American and Spanish types of nets. The fisherman stands on the shore, but still it is best to start training not on a river or lake, but on some lawn or trimmed lawn. Naturally, in field conditions, on a reservoir, before starting preparation, the net is thoroughly cleaned of mud and other aquatic vegetation remaining from the previous cast.

Phases of casting the net

The traction cord is collected in rings in left hand, the tackle is taken with an outstretched hand central part(or by the sleeve - for an American-type net), shake it gently so that the net stretches and straightens. If the load cord has formed a loop somewhere, it must be straightened with your free hand. Then the upper part of the tackle is intercepted with the right hand (from a quarter to half of the net, depending on its radius) and assembled with one or two loops - also in the left hand. Next comes the turn of the cargo cord. He grabs two points with the same left hand and right, and the hands are placed wide enough so that the remaining free part of the net is stretched as much as possible.

If you watch foreign videos, you can see how specialists sometimes, at this stage of preparation for casting, take one sinker in their teeth in order to achieve an even greater stretch of the net.

The next stage is the actual casting itself. It is performed after two or three swinging movements or after one wide swing (in this case, the fisherman’s body turns almost 180°). The most important thing at this moment is the plane in which the tackle moves. The casting net, unfolding on the fly, should fly along the flattest trajectory and finally turn into a circle shortly before touching the water. The latter depends on the strength of the throw, the ability to measure which comes exclusively with training.

Another point where I disagree with foreign instructors: for the most part, they recommend that the loop at the end of the cord be wrapped around the left hand before casting. This works out well during training, but on a pond, when your hands are wet, the tackle can easily fly into the river or lake along with the cord. It is safer to attach the loop to your waist belt.

The described casting technique is not the only possible one. Almost every catcher, with the acquisition of experience, begins to modernize it, adjusting it to his individual characteristics and for specific fishing conditions. For example, you can not collect the traction cord in rings on your hand, but leave it lying under your feet (provided that the shore is clear enough and the cord does not get caught on branches, roots, snags, etc.). The preparation time for casting is reduced, which increases the number of casts per fishing trip and, accordingly, the size of the catch.

Nets with a small radius (up to 1.7 m, for the tallest fishermen - up to 2 m) can be cast without being collected in loops top part networks. Both hands, raised and spread as wide as possible, take the weight cord, the excess cord is collected into loops, 2-3 in each hand, so that the lower edge of the net does not reach the ground 30-40 cm, then the net is thrown, or rather thrown onto a body of water with a characteristic movement reminiscent of those used to throw a wide tablecloth on a table or a sheet on a bed. I even happened to see how two people cast a casting net: two short teenage boys were catching, each of whom could hardly throw the tackle on their own - they took the net by the weight cord, standing on either side of it, stretched it wide in the horizontal plane and, swinging in unison, they were sent into the pond.

Selecting a location

Places that are too deep, with fast currents, with a snaggy or boulder-covered bottom, and with abundant underwater vegetation are definitely not suitable for fishing with a casting net. Steep underwater slopes - the so-called "" - also do not allow you to capture fish holding above them. When fishing from the shore, you should avoid places that are heavily overgrown with trees, bushes, and even such annual vegetation as wormwood, weeds, and so on. at least There should be a clean and level space for a couple of meters around the fisherman.

There is no point in fishing from cliffs, from embankments and bridges that rise above the surface of the water by more than 2 m - the sinker of a net, even a properly cast one, when it falls from high altitude begin to come together, and instead of a regular flat circle, the tackle takes on the shape of an elongated cone. Fishing in unfamiliar places is always fraught with snags, damage to the net and broken veins.

Network sampling

As soon as the load cord of the abandoned net touches the bottom, which is determined by the weakening of the traction cord, the tackle begins to be pulled out with a sharp jerk. This jerk allows, firstly, to quickly bring the sinkers together, closing the exit for the caught fish, and secondly, it raises the net above the bottom, reducing the likelihood of snags.

Fishing tactics

Casting net fishing is no less versatile than fishing, and can be used in a wide variety of conditions, on very different bodies of water and for catching fish with different habits and lifestyles.

Live bait fishing

The easiest way to catch live bait and small fish in general is with a casting net. You just need to choose the right place and make a successful cast, sometimes just one, and if the small fish move in dense schools, then after the first cast three to four dozen fish go into the bucket; Now you can move on to catching a predator with live bait. Neither a boat nor wading fishing is required to obtain live bait; casting is done from the shore. You just need to look in clear water, where minnows lie on a sandbank or schools of perch or roach swim near the seaweed.

Catching big fish

Larger fish are almost always caught blindly, in places where they accumulate. Even when you see a school of such fish in shallow water, you shouldn’t approach them with a casting net; if a fisherman sees a fish, then the fish sees the fisherman, and the flight of the net makes it quickly retreat to the side. During the spring run of fish, it is very convenient to choose places on the river in front of any natural obstacle with a flat bottom and a shallow depth of 0.5 to 1.5 m. Casting is carried out in approximately the same way as spinning fishing: first, the net covers the nearby areas towards the fisherman, then those located at an average distance, then the furthest ones, as far as the length of the towing cord allows. It should be borne in mind that the fish is not very frightened by the splash of a casting net falling on the water (this splash is not loud if the cast is done correctly); the fish does not rush away, but usually rolls slightly downstream. Therefore, the section of the river chosen for fishing should always be fished, moving along the bank downstream.

Spring fishing is done during the day, but as the water clears, the best catches occur at dusk or at night. In summer, when underwater vegetation appears in large quantities of water bodies, the number of places suitable for blind fishing is sharply reduced. It is much more interesting at this time to hunt with a casting net, tracking down single specimens of large fish.

Tench fishing is very exciting. They practice it in shallow areas of the river with a very slow current and a muddy bottom. A sign confirming that the tench is feeding in this place is a chain of bubbles rising from the bottom disturbed by the fish. A boat is not needed; tench feeding areas are usually located close to the shore, sometimes, if the river is not wide and the banks are steep enough, literally a meter from the water’s edge. If at the fishing site there are overly dense thickets of aquatic vegetation, such as water lilies, several clearings should be made in advance, 2-3 times larger than the size of the net. Large bream also often reveal their feeding sites with bubbles. But catching him with a casting net is much more difficult. Bream is more careful, feeds in deeper holes and most often manages to escape from the net that is lowered onto it.

Pike fishing convenient on hot sunny days, traveling together in a boat around shallow bays and channels framed by thickets of reeds or cattails. The boat should have low sides, from whose wide bow it is convenient to cast. Having spotted a pike, usually frozen in mid-water not far from the wall of reeds, the fisherman points it out to the rower, and when the boat approaches a sufficient distance, he throws a net over the fish.
Spring fishing for pike in shallow spawning areas is more productive, sometimes carried out from the shore, but more often by wading. Here you need to master long casting; it is difficult to get close to the spawning pike. Having noticed a place where fish are splashing, the fisherman throws a net over it from the maximum possible distance, and often, along with the caviar pike, pulls out a couple of milk jugs. Unsuccessful casts are also common, when the underwater vegetation on which the pike spawns prevents the net from closing correctly. The spawning of large (kilogram and above) crucian carp does not last long, one or two mornings, but if you manage to get to it with a casting net, the catch will be very pleasing. The place to throw here is sometimes determined not only by splashes, but also by indirect signs: by the movement of the stems of aquatic plants protruding above the water, by the so-called “whiskers” that a shallowly floating fish forms on the surface of the water. big fish, by small fish jumping out of the water in all directions (the fry don’t know whether a peaceful or predatory fish is swimming up to them).

Carp spawning is similar to crucian carp, but carp is a more cautious fish and often spawns in shallow waters further from the shore, overgrown with aquatic vegetation. Therefore, it is better to approach it by boat, maintaining maximum silence.

Casting network - video casting

But it has two design differences:

The network is closed in a ring - thus no terminators are required;
- one of the computers on the network creates a “token” that is passed from computer to computer. Transport protocol, on the basis of which such a network usually operates, is called Token Ring.

What is a marker?

A token is a three-byte frame that is sent from one network node to another. There are two modes of network operation with a marker: normal (network data transfer speed up to 4 Mbit/s) and with fast marker release (data transfer speed up to 16 Mbit/s). Experiments with the introduction of this technology into a 100 megabit network failed, so over time this technology was abandoned in present moment it is outdated and is unlikely to ever come across on your life path.

What is the marker used for?

In order not to clog the network with unnecessary transit traffic and to avoid collisions, a marker is introduced. The principle of operation is this: only the computer that received the token can start transmitting data to another host on the network. If the computer that received the token is not transmitting data, then the token goes to next computer. The remaining computers on the network that are in at the moment do not have a marker, are listeners. The exception to this rule is networks operating in fast token release mode. In these networks, the computer that starts the transmission immediately generates a free token.

The computer that receives the token and has information to transmit changes one bit in the token and starts starter pack which flies to its destination. Having flown a circle, a marker, or next package data is returned to the sending station. In this case, the sending station can check the information from the returned packet and check whether the packet was delivered to the recipient. After this, the package is destroyed.

Token Ring technology has had both its fans and its opponents, however, it, like any other technology, has its pros and cons.

Higher reliability of data transmission, because the network is used in a more “organized” manner and there are no collisions;
- low cost of installation, although more cable is required;
- if one network node fails, the remaining nodes continue to operate fully (unless the cable is damaged).

Each workstation on the network is connected by cable to another workstation and one or more servers. Word topology means a diagram of the physical arrangement of cables connecting computers into a single network. In general there are three types of topology computer network.

Tire. All computers on the network are connected to each other in series. The network connection starts with the server and ends latest system online.

Star-shaped. Each computer on the network connects to a central access point.

Ring. Each computer on the network is connected to others in a ring or loop pattern.

Several topological schemes can be combined in one network. Such networks are called hybrid. For example, hubs of multiple star networks can be connected via a bus network, thereby forming a star bus network. Networks with a ring topology can be combined in exactly the same way.

Bus topology

Sometimes between the two most distant friend A single cable is laid from each other's workstations, bypassing all other stations and servers. This connection method is called bus topology(Fig. 9). However, this connection method has a significant drawback: if the workstation or cable and connections fail for some reason, all other objects located further down the line will lose contact with the network. This topology is used when creating a local network using thick and thin Ethernet cables. However, the advent of cheaper and more compact unshielded twisted pair cables, which are also suitable for fast data transfer, makes the previous disadvantage bus topology less obvious. If problems occur with specific computer or by cable connection, all stations located behind this system can be disconnected from the network. Problems with thin Ethernet (10BASE-5) networks often occur due to the AUI device becoming loose on the coaxial cable. In addition, T-adapters and termination resistors on a thin 10BASE-2 Ethernet network can also become loose or be disabled by the user, causing serious damage to the functioning of the entire network or its individual components.

Another disadvantage of 10BASE-T occurs when connecting a new system to a network between existing systems. As a result, separation may be required network cable between computers into shorter segments, which is necessary to connect the network card and T-adapter of the new computer.

Res. 9. In a serial bus topology, all network devices are connected to one cable

Ring topology

Discussions about networking often refer to a ring topology, in which each workstation connects to the next and the last one connects to the first (similar to a bus topology with connected ends). There are two main types of networks using a ring topology:

FDDI, which uses a physical ring topology;

Token-Ring, using a logical ring topology.

In fact, it is not physically necessary for the cables to be connected in a ring. In fact, the ring only exists inside the Token Ring hub (the so-called MultiStation Access Unit - MSAU). The Token-Ring topology diagram is shown in Fig. 10. The signal sent by one computer goes to the hub, and from the hub it is sent to the next computer, after which it goes to the hub again. In this way, the data travels to each computer until it reaches the computer that sent it again, which retrieves it from the ring. Thus, although the physical topology of the wires is star-shaped, data in such a network is transmitted through the so-called logical ring.

A logical ring is more convenient than a physical ring topology, since such a system has higher fault tolerance. In a bus network, a cable failure brings the entire network to a standstill. In Token Ring, the multi-user access module can simply disconnect the failing computer from the logical ring, allowing the rest of the network to continue operating.

Res. 10. Data transmission in the Token-Ring network

Ring (computer network topology)

The work in a ring network is that each computer relays (renews) the signal, that is, acts as a repeater, therefore the attenuation of the signal throughout the ring does not matter, only the attenuation between neighboring computers of the ring is important. In this case, there is no clearly defined center; all computers can be the same. However, quite often in the ring there is special subscriber who manages or controls the exchange. It is clear that the presence of such a control subscriber reduces the reliability of the network, because its failure will immediately paralyze the entire exchange.

Computers in a ring are not completely equal (unlike, for example, a bus topology). Some of them necessarily receive information from the computer that is transmitting at this moment earlier, while others - later. It is on this feature of the topology that methods for controlling network exchange, specially designed for the “ring,” are based. In these methods, the right to the next transmission (or, as they also say, to take over the network) passes sequentially to the next computer in the circle.

Connecting new subscribers to the “ring” is usually completely painless, although it requires a mandatory shutdown of the entire network for the duration of the connection. As with the bus topology, maximum quantity The number of subscribers in the ring can be quite large (1000 or more). The ring topology is usually the most resistant to overloads; it ensures reliable operation with the largest flows of information transmitted over the network, because, as a rule, there are no conflicts (unlike a bus), and there is no central subscriber (unlike a star) .

In a ring, unlike other topologies (star, bus), a concurrent method of sending data is not used; a computer on the network receives data from the previous one in the list of recipients and redirects it further if it is not addressed to it. The mailing list is generated by a computer, which is the token generator. The network module generates a token signal (usually about 2-10 bytes to avoid attenuation) and transmits it to the next system (sometimes in ascending order of the MAC address). The next system, having received the signal, does not analyze it, but simply transmits it further. This is the so-called zero cycle.

The subsequent operating algorithm is as follows - the GRE data packet transmitted by the sender to the recipient begins to follow the path laid by the marker. The packet is transmitted until it reaches the recipient.

Comparison with other topologies

Advantages

• Easy to install;
• Almost complete absence of additional equipment;
• Possibility of stable operation without a significant drop in data transfer speed under heavy network load, since the use of a marker eliminates the possibility of collisions.

Flaws

• The failure of one workstation and other problems (cable break) affect the performance of the entire network;
• Complexity of configuration and setup;
• Difficulty in troubleshooting.
• The need to have two network cards,at each workstation.

Application

It is most widely used in fiber-optic networks. Used in FDDI, Token ring standards.

Links

• Computer network topology: bus, star, ring, active tree, passive tree

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See what “Ring (computer network topology)” is in other dictionaries:

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This term has other meanings, see Tire (meanings). A common bus topology is a common cable (called a bus or backbone) to which all workstations are connected. At the ends of the cable there are terminators, ... ... Wikipedia

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Mesh topology is a basic fully connected topology of a computer network in which each workstation... Wikipedia

A bus topology is a common cable (called a bus or backbone) to which all workstations are connected. There are terminators at the ends of the cable to prevent signal reflection. Contents 1 Networking ... Wikipedia

Computer network ( computer network, data transmission network) a system of communication between two or more computers and/or computer equipment (servers, routers and other equipment). Various ... ... Wikipedia can be used to transmit information

Did you know What is the falsity of the concept of “physical vacuum”?

Physical vacuum - the concept of relativistic quantum physics, by which they mean the lowest (ground) energy state of a quantized field, which has zero momentum, angular momentum and other quantum numbers. Relativistic theorists call a physical vacuum a space completely devoid of matter, filled with an unmeasurable, and therefore only imaginary, field. Such a state, according to relativists, is not an absolute void, but a space filled with some phantom (virtual) particles. Relativistic quantum field theory states that, in accordance with the Heisenberg uncertainty principle, virtual, that is, apparent (apparent to whom?), particles are constantly born and disappeared in the physical vacuum: so-called zero-point field oscillations occur. Virtual particles of the physical vacuum, and therefore itself, by definition, do not have a reference system, since otherwise Einstein’s principle of relativity, on which the theory of relativity is based, would be violated (that is, an absolute measurement system with reference to the particles of the physical vacuum would become possible, which in turn would clearly refute the principle of relativity on which the SRT is based). Thus, the physical vacuum and its particles are not elements of the physical world, but only elements of the theory of relativity, which do not exist in the real world, but only in relativistic formulas, while violating the principle of causality (they appear and disappear without cause), the principle of objectivity (virtual particles can be considered, depending on the desire of the theorist, either existing or non-existent), the principle of factual measurability (not observable, do not have their own ISO).

When one or another physicist uses the concept of “physical vacuum,” he either does not understand the absurdity of this term, or is disingenuous, being a hidden or overt adherent of relativistic ideology.

The easiest way to understand the absurdity of this concept is to turn to the origins of its occurrence. It was born by Paul Dirac in the 1930s, when it became clear that denying the ether in its pure form, as was done by a great mathematician but a mediocre physicist, was no longer possible. There are too many facts that contradict this.

To defend relativism, Paul Dirac introduced the aphysical and illogical concept of negative energy, and then the existence of a “sea” of two energies compensating each other in a vacuum - positive and negative, as well as a “sea” of particles compensating each other - virtual (that is, apparent) electrons and positrons in a vacuum.