About the bridge and router

Introduction

In this current assignment I will discuss about the bridge and router. This assignment I will explain the definition of what is a bridge and a router in detail. The bridge and router has its own advantages and disadvantages in many ways by looking thru its capability and specification wise. Bridge is a wired connection which is only use for that computer which is connected to it and router is a wireless connection which can be shared by many other computer or laptop. Secondly, I will calculate and find the subnet mask, number address in each subnet and first and last addresses in subnet.

1.The answer is yes it is possible to replace the bridge with a router. Thru coming year our technology is expanding rapidly because of that many alternative way can be done to solve networking problem. I will explain what are a router (refer to figure1.1) and a bridge (refer to figure1.2) individually in performing a task to connect thru the network. 

In telecommunication networks of today, the bridge is a device that enables us to connect to the local area network known as local area network to another local area network which uses the same protocol as Ethernet or token ring. You can imagine that the bridge device as being to be able to decide whether a certain context of message from another person to someone else is by going thru to the local area network in your current building or to someone else on the local area network in another building which is located across the street. The bridge examines or checks each message carefully on a local area network, passing thru those which are known to be within the same local area network, and forwarding those which are known to be on the other interconnected local area network.

In bridging networks of today, a computer address or a node address have no accurate or specific relationship to location where it is located. For this reason, messages are randomly sent out to every single address located on the current network and only can be accepted by the intended and matching destination node. The bridge learns which addresses are on specific network and create a learning table in order for each subsequent message to be forwarded to the correct network.

Bridging networks commonly are always interconnected local area networks since broadcasting each and every message to all available destinations would causes a flood to the larger network with unwanted traffic. For this reason, router networks such as the Internet use a scheme that assigns addresses to nodes so that a message or packet can be forwarded only in one general direction rather than forwarded in all directions.

A bridge operate at the data-link level of a network also known as physical network, is by copying a data frame from another network to the next network by moving along the communications path. A bridge contains more overhead and lesser amount of repeater. The bridge processes the packet at only the two layers; the repeater processes each frame at only on one layer. The bridge will need to look for a table and get the forwarding port together for it to regenerate its signal; only the repeater will regenerates the signal.

The transparent bridge works by using two processes known as bridge forwarding and bridge learning. If the destination address exists in the forwarding database which is already created, the packet will then be forwarded to the port number to the specific destination host which has been attached. If it doesn’t exist in the forwarding database, forwarding will be done on all parts which cause flooding. This process is referred as bridge forwarding. Moreover, as each frame reaches it destination, its source address will indicates where a particular host is located, so that the bridge knows where to forward the frames to that address. This process is called bridge learning. The key features of a transparent bridge is that the stations are not aware of the existence of a transparent bridge and reconfiguration of the bridge is not required because it can be added or removed on its own without knowing.

The advantages of bridging is that it’s self-configuring which doesn’t require any skillful technically expertise to configured it because is not as complex as the router. Secondly, the price of a simple bridge device is not expensive at all compared to the router. Thirdly, it isolate collision domain which will reduce the size of collision domain by using micro segmentation in the non-switched network. Fourthly, bridges won’t deny the introduction of management or performance information and access control. Fifthly, local area networks interconnected in the bridge are divided and the physical constraints like the number of station, repeater and segment length will not be apply. Sixthly, the bridge manages incoming trafficking and lessens the bandwidth to be wasted by avoiding all unwanted flow of data located in between the network segments. By using this method it can effectively ensure that the optimal performance on both sides of the network segment. Bridges might be functioning just like a traffic police on the city street, by controlling the movement of the legitimate data and not allowing all unwanted traffic passing through it. Bandwidth that is wasted will create unwanted delay of time and reduce the performance speed of the current network used. A bridge is therefore can also act as a bandwidth monitor, by channeling important relevant data and discarding rubbish to improve the bandwidth throughput. It also can be thought out as a traffic shaping or a managing firewall. Seventhly, the network bridges improve the functional length of a network by connecting each single local area network segments. A network is possible to be segmented and join together without requiring the need of creating IP subnets or the usage of a router. The network bridges expand the capacity of the network without the requiring for hardware equipment something like cables, and software constraints which is the firewalls. Eighthly, the bridge network is capable of connecting both similar and different local area network segments. It is connected, for an instance, an Ethernet segment connected together with a Token Ring segment, which allows both to function as one and by having similar IP address. A bridge connects local area network segments thru many different protocols, a local area network segment including the Internet and a wireless local area network (WLAN) with a local area network segment. The bridge network can also be used to connect two carrier sense multiple access or collision detection (CSMA/ CD) local area network, and a token ring local area networks with a carrier sense multiple access or collision detection (CSMA/ CD) local area network. It is important to connect different segments possessing non-similar protocols for data transmission.

The disadvantages of bridging are that the scope of broadcast has no limit in the bridge network. Secondly, extremely large networks are not being scaled in the bridge network. Thirdly, the bridge network delays the length of time for the action to do buffering and processing. Fourthly, repeater and hubs cost a lesser amount of price compared to buying a bridge.  Fifthly, a complex network topology can pose a problem for transparent bridges. For example, multiple paths that are located in between the transparent bridges and local area network can cause the bridge looping. The spanning tree protocol is to help in reducing the problems with complicated topologies.

In packet-switching networks such as the Internet which connect to the world wide web, the router is a device that is capable, in some cases, software that are inside the computer, so that it determines from one network to another network point in which a single packet should be  forwarded toward its right destination. The router is connected with at least two networks or more networks and it determine which way to send each packet containing the information based on its own knowledge of the current condition of the working networks that it is connected to. A router can be located at any gateway in where one network can be met with another network, including each point-of-presence on the Internet will surfing in the World Wide Web (WWW). A router is most of the time is included as a fraction from the network switch.

The router sometimes can create or maintain the table for the current routes used and its own conditions and using the information together with distance and cost the algorithm to decide on its own to choose the best route for each packet that’s been given. Typically, a single packet sometimes moves through a specific number of network points with the use of routers before reaching at its currently set destination. Routing will function by associating with the Network layer which is located in layer 3 where it is in the standard model of network programming, it is called the Open Systems Interconnection (OSI) model. A layer-3 switch allows the switch to be able to perform routing functions properly. An edge router is another kind of router that interfaces with an asynchronous transfer mode (ATM) network. A brouter is combined with a bridge network and a router.

For the home computer users and business computer users which owned a high-speed Internet connection by using a cable, satellite, or digital subscribe line (DSL), the router can be like a hardware firewall. This fact is true because even though if the home or the business owned only a single computer at home or at work place. Out of many of the engineers’ trust that the usage of a router provides a higher protection level against hacking by hacker compare to a software firewall inside the computer, because none of the computer Internet Protocol address are easy to be revealed to the Internet. This makes the port scan which is a technique for exploring weaknesses almost essentially impossible to be done. In addition, a router does not simply suck up the resources in the computer as a software firewall does. Commercially manufactured routers are easily to be installed, its sold at a reasonable price, and made available for hard-wired network or wireless networks.

The advantage of using a router is that the data can be travel between different networks, so that you can use the local area network and wide area network connectivity at the same time. The router has many different type of connections which can be connected to a lot of architecture, many kind of media from the internet and also for internal use within an organization. The router is useful for transferring data to others because it makes its own decision by taking the best route and paths in order to get the correct data to the target node. Router has domain that will cause smaller collisions. Wireless Internet also known as the router provides super quick broadband speed, approaching up to two megabytes per second or even quicker. More and more customers are hoping for the broader bandwidth, so the number should slowly crawl up steadily over for the next few months or years to come. Wireless internet is more reasonable and has better performance wise over the satellite broadband , this is because satellite signals typically needs to travel around tens of thousands of miles away. Wireless internet is also extremely responsive, when you are launching up the web pages, downloading emails is quicker, and able to engage in teleconferencing or video conferencing over the internet, your wireless internet system will be able to yield ultra quick transmission. Weather condition, radio frequencies distraction, and traffic congestion can all impede wireless internet flow. Moreover, with the building of transmission towers across each nation, it safe to say that if people who live within a average proximity of an urban area, those people will be more closer to the wireless Internet tower. The wireless Internet broadband service allows rural Web surfers a certain way to get into the high speed telecommunications without requiring to lay down the fiber or reconfiguring in the public switched telephone network system according to the updated digital subscribe line (DSL) standards. Thus, sending communications to a much smaller town in certain area which lacks of cable infrastructure or merely seeking to dodge the slow speed and sometimes complicate the plans associated with digital subscribe line (DSL), wireless Internet is just a beautiful method to boost your surfing time.

The disadvantages of a router is because of the cost of the router will be more as it is more expensive compared to the hub, bridge & switch. The router has more bandwidth when it is interconnected with many buildings or when it is doing some updating.The router must have a larger latency during the time when there are a lot of packets to be sorted. With the help of wireless Internet service, there still the problem of someone with bad intention, inside within the wireless traffic, hacking to get into your own connection from a distance away and its done by a person known as a hacker. So, you will need to make sure that you’re using the wireless security to make sure all the private information in it is kept safe from other stranger viewers such as hacker. There are many available firewalls which work and perform task better enough for this specific purpose or you can just go look into by using the network system which is able to create a password protected connections.

Verizon wireless and Sprint wireless are two out of many popular wireless companies in the business of today. Verizon wireless offers several different kinds of wireless devices which are often used by customer. Hand phones and wireless broadband Internet are also very popular services that they currently offering. Not only that they also provide service for personal digital assistant (PDA) and wireless personal computer (PC) cards. Wireless technology can appear in many different kind of various forms as well. You will be able to find wireless speakers for the stereo system also, wireless headphones for communicating, wireless receivers and transmitters and even microphones to talk over the net. You can also find wireless computer mouse, wireless keyboards, satellite television (TV), cordless telephones and even the garage door controller without manually doing it. In the next coming generation will probably bring us to a world filled with many kind of wireless technology devices. Hard wired devices will in the end up as being a device or a thing from the past generation, once wireless technology will enlarge. As the wireless Internet technology improves, personal digital assistants (PDA), blackberry devices, and other well known hand phones or personal computer (PC) hybrids will likely depend on it increasingly on non-fiber based transmissions. Thus by learning yourself for now about the current wireless Internet trends and developing initiatives, that you can knowingly position yourself as the earliest adopter of the next generation of Wi-Fi concerned technologies. Understanding what is what at its cutting edge of telecom tech development will also fill your overall investment portfolio.

Bridge device has some similarity with a router, but it does not analyze the data that is being forwarded. Because of this, bridges are typically quicker at transferring data, than but not as versatile as a router. For example, the bridge cannot work as a firewall like most of the routers can in which show the disadvantages of the bridge compare to the router. A bridge is capable for transferring data between different protocols such as a Token Ring and Ethernet network. A router on the other hand are like traffic police, they examine each single packet of data, get the accurate destination address and forwards it thru the network to be sent to the right address.

Bridging and routing are both method of performing data control, but it work through many kind of different methods. Bridging takes place at Open Systems Interconnection (OSI) Model Layer 2 which is referred as data-link layer while routing takes place at the Open Systems Interconnection (OSI) Model Layer 3 which is referred as network layer. This difference the meaning of a bridge and a router where a bridge directs frames by following the hardware assigned media control access (MAC) addresses while a router makes its own decisions based on the arbitrarily assigned internet protocol (IP) Addresses. As a result of that, bridges are not bothered with and are not able to recognize networks while routers can capable of doing that.

Open System Interconnection (OSI) Model Layer 2 is the protocol layer which will transfer the data located between the adjacent network nodes in the wide area network (WAN) or in between the nodes on similar local area network (LAN) segment. Data link layer also provides functional and procedural means to move the data between network entities and sometimes provide the means to spot and mostly correct errors that may happen in the Physical Layer. Data link layer is also related with local delivery of frames in between the device on similar local area network (LAN). Data link frames, as these protocol data units are used to be referred as, will not go over the limit of a local network. Inter-network routing and global addressing are bigger layer functions, allowing data link protocols to concentrate on local delivery, addressing, and media arbitration. By using this way, the data link layer is analogous to specific neighborhood traffic cop; it endeavors to arbitrate in between parties contending for gaining access to the medium. When a devices attempt to make use of a medium during the same time, frame collisions happen. Data link protocols specify how devices spot and heal from such collisions, but it will not stop it from occurring. Delivery of frames from layer 2 devices can affect the use of unambiguous hardware addresses. The frame’s header will contains source and location addresses that will show which device originated the frame and which device can be ignore to get and process it. In other word, the hierarchical and routable addresses from the network layer, layer two addresses are flat, meaning there’s no part of the address that might be able to be used in order to find out the logical or physical group to which the address come from. The data link also provides data transfer moving across the physical link. That will be able to transfer many data link protocols which do not have acknowledgments of successful frame reception and acceptance, and certain amount of the data link protocols maybe will not even have any form of checksum to find or scan for the transmission errors. In this case, higher-level protocols will provide flow control, error finding, and acknowledgments and retransmission.

Open System Interconnection (OSI) Model Layer 3 is the network layer job is to do end-to-end packet sending including routing thru intermediate hosts, where else the data link layer job is to do node-to-node frame sending on similar links. The network layer will also provides functional and procedural means of transferring changeable length data sequences from one source to one location host thru a single or multiple network while maintaining the standard of the service and error control functions.

This difference the meaning of a bridge and a router where a bridge directs frames by following the hardware assigned media control access (MAC) addresses while a router makes its own decisions based on the arbitrarily assigned internet protocol (IP) Addresses. As a result of that, bridges are not bothered with and are not able to recognize networks while routers can capable of doing that.

When designing or creating a network, one can choose to insert multiple segments into a single bridged network or to divide them into many different networks interconnected by using routers. If a host is physically transferred from the current network area to next network in a routed network, it has to obtain a new internet protocol (IP) address; if the system has been transferred within the bridged network, it doesn’t have to be change or modified anything.

The consequence which by replacing a bridge with a router is that the router will cost more expensive than the price of a bridge and more complex to be set up or understand compared to a bridge. Secondly, router operates only at the first three-layers of the network while the bridge operates only at the first two layer of the network. Thirdly, is that router are not created to provide direct filtering compared to a bridge which does it. Fourthly, a router normally requires a longer amount of time which makes it time consuming in order for it to search for the routing table compared to searching for the filtering table which takes up lesser amount of time to be searched. Fifthly, a router is required to decapsulate and encapsulates the specific frame and modified the current physical addresses in the frame because the physical addresses in the arriving frame define the old node and the present router; both must be change to the physical addresses following the current router and the next hop. The bridge does not modify the current physical addresses. Changing addresses, and other fields, in the frame means causing a lot of unwanted overhead.

2a) Log² 500=8.95 extras 1s=9 possible subnets: 29=512 mask: 9+8=/17

b) 232-17=215=32768 addresses for each subnet

c) The first subnet:

The first address is the starting address of the block.

16. 0. 0. 0

In order to find the last address, you need to write 32,767 (one lesser than the number of

addresses in each subnet) in base 256 (0.0.127.255) and adding it with the first

address (in base 256).

First address in subnet 1: 16.0.0.0

Number of addresses: 0.0.127. 255

Last address in subnet1: 16.0.127.255

d) The last subnet:

Note that the subnet 500 will not be the last possible subnet; but it will be the last subnet used by the organization. In order to find the first address in subnet 500, you will need to add

16,351,232 (499 Ã- 32678) in base 256 (0. 249.128.0) into the first address in subnet

First address in subnet 1: 16.0.0.0

Number of addresses: 0.249.128.0

First address in subnet 500: 16.249.128.0

Now you can be able to calculate the last address in subnet 500.

First address in subnet 500:16.249.128.0

Number of addresses: 0.0.127.255

Last address in subnet 500: 16.249.255.255

Conclusion

In conclusion, we learn that bridges and router has their own advantages over each other. For example, the bridge will not be distracted by any other device which will intercept the connection because it uses cable to connect to the network without moving thru the air. Another example is that the router is able to be connected by many other computers within a certain range in distance unlike bridge which is able to be used by a single connected computer only. There are consequences of replacing the bridge with the router is that the router will cost more than the price of the bridge.

Abstract

In telecommunication networks of today, the bridge is a device that enables us to connect to the local area network. The bridge examines or checks each message carefully on a local area network. In bridging networks of today, a node address have no accurate relationship to location where it is located. Bridging networks commonly are always interconnected local area networks. A bridge operates at the data-link level of a network by copying a data frame from another network to the next network. A bridge contains more overhead and lesser amount of repeater. The transparent bridge works by using two processes known as bridge forwarding and bridge learning. The advantages of bridging is that it’s self-configuring which doesn’t require any skillful technically expertise. The disadvantages of bridging are that the scope of broadcast has no limit. The router is connected with at least two networks or more networks and it determine which way to send each packet. Routing will function by associating with the Network layer which is located in layer 3 where it is called the Open Systems Interconnection (OSI) model. The advantage of using a router is that the data can be travel between different networks. The disadvantages of a router is because of the cost of the router is more expensive than the hub. Bridging and routing are both method of performing data control. Bridging takes place at Open Systems Interconnection (OSI) Model Layer 2 while routing takes place at the Open Systems Interconnection (OSI) Model Layer 3. Protocol layer will transfer the data located between the adjacent network nodes and network layer job is to do end-to-end packet sending. The consequence which by replacing a bridge with a router is that the router will cost more expensive.

Reference

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12) (figure1.1) Available from:http://www.belindahaikes.com/VisualCultureandTechnology/VC&T1998/68573-router-diagram.gif

13)(figure1.2) Available from:http://www.oreillynet.com/network/2001/03/16/graphics/Figure4_2.jpg