Do you understand the interconnection of the Internet ? A switch creates multiple collision domains , but these collision domains belong to the same broadcast domain ; while each interface of a router belongs to a different broadcast domain , please be sure to understand this.
Bridging existed before routers and hubs , so people often confuse bridges and switches because they basically do the same thing , dividing a LAN into multiple collision domains. In fact , there are no bridges available today , just LAN switches , but they use bridging technology , so Cisco and others still refer to them as multiport bridges.
Does this mean that switches are just smarter multiport bridges? More or less , but with some important differences. Switches do provide bridging functionality , but their management capabilities are vastly improved. Also , most bridges have only two or four ports , which is a major drawback. While you may come across bridges with as many as 16 ports , some switches have hundreds of ports , which is nothing compared to that .
Using bridges in a network reduces collisions in broadcast domains and increases the number of collision domains in a network. Doing so will provide users with higher bandwidth. Don’t forget that using a hub can lead to more congestion on the Ethernet. Be sure to plan your network design carefully.
Remember that the router not only makes each LAN interface a separate broadcast domain , it also splits collision domains. The
router sits at the center , linking all the physical networks together . This layout was necessary given the system’s legacy of bridges and hubs . While I sincerely hope you don’t come across a network like this , the message conveyed is important.
The top of the Internet uses a bridge to connect the hub to the router. The bridge splits the collision domains , but all hosts connected to the two hubs belong to the same broadcast domain. Also , the bridge only creates three collision domains (one for each port) , which means that all devices connected to the same hub belong to the same collision domain. This is bad and should be avoided if possible , but better than having all hosts belong to the same collision domain. So do n’t do this at home , this inefficient design should go to a museum , it’s a perfect example of what to do , it’s a bad design for today’s web. It lets us know the ins and outs of network interconnection , and you must understand the concepts explained in it.
Also note that the bottom three hubs connected to each other are also connected to the router , and they form a collision domain and a broadcast domain , making this bridged network look much better .
Although bridges/switches are used to segment networks , they cannot isolate broadcast and multicast packets.
Of the networks connected to this router , the best is the switched network on the left. Why? Because each port of the switch belongs to a separate collision domain , but that’s not good enough because all devices in that network belong to the same broadcast domain. This can actually be bad , do you remember why? All devices have to listen to all broadcasts , that’s why. The larger the broadcast domain , the less bandwidth is available to users , the more broadcasts must be processed , and the network’s response time will be slow enough to cause an office riot. Therefore , in today’s networks , it is important to keep broadcast domains small.
Here , I put the LAN switch in the center of the network, and the router connects only the logical networks. With this configuration, virtual LANs (VLANs) are created to divide the Layer 2 switched network into logical broadcast domains. However , it is important not to forget that
even in a switched network environment , routers are still required to support inter-VLAN communication . Obviously , the best network is one that is properly configured to meet the business needs of a company or client. Optimal network design is one that uses the correct combination of LAN switches and routers in the network. I hope this article helps you understand the basics of routers and switches so that you can make the right decisions based on your specific situation.
Let’s take a moment to take a closer look. In the Internet shown in the figure , how many collision domains and broadcast domains are there? There are 9 collision domains and 3 broadcast domains . I hope your answer is the same. Broadcast domains are the easiest to identify because , by default , only routers divide broadcast domains. Given that there are 3 router connections , there are 3 broadcast domains. But do you understand that there are 9 collision domains? If not , let me explain. The bottom network with only hubs has one collision domain; the top network with bridges has three collision domains plus five in the switched network (one for each switch port) , for a total of nine.
Each switch port corresponds to a collision domain , and each VLAN corresponds to a broadcast domain. In your opinion , how many collision domains are there? The answer is 12: Please don’t forget that each connection of the switch corresponds to a collision domain! Since the figure does not list VLAN information , we assume that it is the default , that is, only a broadcast domain. Should
-World Switches Replace Existing 10/100MbUs Switches?
Suppose you are a network administrator of a large company , and you want to buy a new batch of switches , but the boss thinks the cost is too high , so he asks you to discuss. Should you try to convince your boss? That is, do you really need to buy it?
If you can afford it , you should. The newest switches offer features that older 10/100Mbts switches don’t (currently , a 5 year old switch is pretty old) , but most companies don’t have an unlimited budget to buy a brand new gigabit switch. It’s also possible to build decent networks using 10/100 Mbits switches—provided they’re designed and implemented correctly, of course. Sooner or later you’ll have to replace those switches , please plan and budget for that Another good question is , for all the users, servers and other equipment , do they need to be connected to 1Gbit/s or better switch ports? Yes , absolutely New high-end switches are needed! Because the bottleneck of the internet is no longer the servers and mainframes , but the routers and switches – especially older routers and switches! Every desktop and router interface has to be at least gigabit , if affordable , preferably 10 Gbit/s or even higher. So do it your way! Put in a request to buy a brand new Switch , and you’ll be a hero in no time.
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