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130 votes
Accepted

Why do switches say 10/100/1000?

Not the same thing at all. Indeed, there exists no such thing as "up to". 10/100 Mbit/s uses the same cable (ignoring different specifications for the shielding, which is negligible from the switch's ...
  • 4,452
77 votes
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Why is a router needed?

I think generally routers serve as an access point, DHCP, firewall and switch as an easy solution for people who don't know much about networking No, routers are a separate kind of device from APs ...
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64 votes
Accepted

Why use half duplex at all?

Full duplex requires more than half duplex. Typically full duplex is achieved by having two separate data paths. That means two sets of wires, separate sets of transmission and receiving electronics ...
  • 85k
56 votes
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Do 'dumb' (non-smart, non-managed) switches have an IP address?

An unmanaged switch does not even know what IP is. It will forward IP packets as well as many other protocols without ever understanding what the difference is. All the switch needs to know in order ...
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52 votes
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How should I connect 7 devices to a switch module with four ethernet interfaces? Is there a preferred topology?

The thing to keep in mind is that the link between the switch and the router is shared between all devices trying to communicate across the link. If: the devices predominantly connect to the ...
44 votes
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Crossover cable or straight through between multiple hubs/switches

Most modern hardware – Ethernet switches and computer Ethernet interfaces – implements Auto-MDIX, automatically choosing the correct mode for each physical connection. (This is now a required part of ...
  • 387k
39 votes

Why do switches say 10/100/1000?

They are entirely different standards - it's not like an ADSL connection that essentially does "the best it can" to get data to you at your hoped-for speed [the famous "up to" advertising lies claims ...
  • 41.3k
39 votes

My ISP doesn't use a modem. How does this work?

There could be a modem connecting to the switch/router gear that is in the other side of that Ethernet connection, however a modem is not mandatory. Depending where you are, it is entirely probable ...
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38 votes
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Why are there no wireless switches?

Switches are intelligent networking devices that take signals in from a particular port and then rebroadcast it on a specific port that it knows has previously hosted the intended recipient. In the ...
  • 85k
36 votes
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My IP addresses changed from 192.168.2.xxx to 192.168.1.xxx. I can't reach the switch anymore

Temporarily change one of your computers' IP address to be in the 192.168.1.0/24 range and you should be able to connect to your switch (you will be disconnected from the Internet). Then just ...
  • 486
31 votes
Accepted

My ISP doesn't use a modem. How does this work?

Modems are not a requirement, at all. They just happen to be the common case in many parts of the world because they allow usage of existing (quite often old) telephony or cable television ...
28 votes

Can I connect a PC to a PoE switch?

Updated answer for 2016. The good news is: if you have a switch or injector that doesn't claim to be "passive" and conforms to 802.3af (the PoE standard) or 802.3at (the PoE Plus standard), it will ...
27 votes
Accepted

Do I need MAC addresses if I'm connecting Raspberry Pi Zeros together together on a subnet via a switch?

If you are networking in any way with common networking interfaces you have MAC addresses whether you know it or not but you shouldn’t really have to worry about them. So, I understand your question ...
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27 votes
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How does the computer know which switch to send the packet to?

It doesn't send it to a switch at all. It sends it out of whichever interface has the correct IP address and subnet or, if both are valid, whichever it believes is faster or has the fewest hops to the ...
  • 85k
24 votes
Accepted

Multiple switches - how does it work?

If Switch 1 doesn't know what port the frame (not packet!) is meant to go to, it will flood all ports (except the port the frame originated from). One of those ports will be connected to Switch 2, ...
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24 votes
Accepted

How a switch works when it's aware of MAC address but the sending PC isn't aware of MAC of destination MAC

The ARP request will of course go through. The switch doesn’t know about ARP. It only knows about Ethernet (ie. MAC addresses on Ethernet frames), not protocols on top of it. (Some switches offer ...
  • 55.1k
22 votes

Why use half duplex at all?

With the exception of some networking connections (e.g., router to internet, server to local network), most usage - whether older serial or parallel, USB, ethernet or almost anything else is mostly ...
19 votes
Accepted

Is a switch just a simple router?

No, switches are not just simplified routers. Although many devices combine functions of both routing and switching, the two functions are distinct. Switches create networks, routers connect distinct ...
  • 2,106
17 votes

How should I connect 7 devices to a switch module with four ethernet interfaces? Is there a preferred topology?

Unless you already have a 5-port switch lying around and are too poor to afford buying the 8-bit switch, the second alternative is certainly the better one, in general. There may be valid reasons for ...
  • 4,452
15 votes
Accepted

Why does my HP switch appear to be reporting inconsistent information?

I finally figured it out: My company has bought many HP switches over time of similar types (1700-8 (J9079A), 1800-8G (J9029A), 1810G-8GE (J9449A)) and installed them without changing the IP address ...
14 votes

How switch will learn MAC in these situations?

Switches don't send packets to discover the MAC addresses, they listen to the traffic and in that way they create a table relating the MAC address with the port from where the frame came. In the ...
  • 16.9k
12 votes

Why are there no wireless switches?

With (wired) ethernet, you can have switched because you can have a non-shared medium (individual cables not all hard-wired together like they would be in a hub). With wireless, you inherently have a ...
11 votes

How a switch works when it's aware of MAC address but the sending PC isn't aware of MAC of destination MAC

An ARP request is simply a message that says "You there at IP whatever! What's your MAC address?" Even though ARP deals with discovering layer 2 addresses, it's inherently a layer 3 request because it'...
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11 votes

How does the computer know which switch to send the packet to?

It depends what sort of a setup you have. You could have two network interfaces on the computer, connected to two completely distinct networks. In that case, the packets would go out of the interface ...
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10 votes
Accepted

Can I use Cat6 cables on a Cat5 switch?

What makes Cat 5 and 6 cables different are their electrical specifications and therefore signal transmission capabilities. Category 6 cable has better specifications than 5 or 5e, enabling it to so ...
9 votes
Accepted

Maximum Bandwidth through gigabit switch

With a well-designed Ethernet switch, it's possible to get the full port speed into each port and the full port speed out each port, all simultaneously (switch ports are full-duplex). A switch ...
  • 98k
9 votes

Can I create two separate private networks with only one IP address using only two routers and a switch?

As presented in the drawing, no. Firstly a standard ISP residential contract provides a single public IP address; more than that usually requires a substantially more expensive commercial contract. I ...
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8 votes

Why are there no wireless switches?

The closest concept to a wireless switch is a signal booster or repeater, which are devices that do pretty much exactly what they sound like. Nobody calls them a switch though, because they're ...
8 votes

Can I plug my modem to an ethernet switch for my router to use?

No, your Linksys CM3024 is a pure DOCSIS modem (that is, it does not include any gateway/router functionality), and the DOCSIS specification doesn't allow a modem to talk to more than one device. ...
  • 98k

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