Network Switch 101

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zodiacfml

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The article is all over the place. It will just confuse a basic consumer. Layer 3 switches need not to be mentioned as they are for organizations. Networking "hub" need not also to be mentioned as you cannot purchase a "new" one anymore and the article doesn't explain well why it causes collisions. I also don't know why it has to mention enterprise equipment and racks.

One thing it also fails to mention are home Wi-Fi routers. They are all in one devices that almost have four extra LAN ports for connecting a LAN cable. These ports are made possible as they have an integrated "switch" device. If that is sufficient then a consumer might not need a switch.

In some larger homes, you might want to add a switch connected to a Wi-Fi router to increase the number of available of ports. First reason, a homeowner might need LAN ports immediately in wall outlets. Second, for installing and filling the home with Wi-Fi access points. Third reason is for other IP devices such as security cameras, IP phones, and others. So, one major feature excluded in the article is PoE. An advanced home network might need to deploy a PoE switch if it has security cameras and Wi-Fi access points at the same time to avoid the need of using power adapters for each networking device. PoE discussion can be expanded as it has two power level standards which can be an issue with Wi-Fi ac standard access points.
 

boju

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I fried a switch once...

Wanted a USB to RJ45 dongle for the WiiU instead of using it's wireless. EB games/Dick Smith didn't sell Nintendo's dongle anymore so got near enough what i thought might work. One of those USB to RJ45 but came with two ends, i thought one end was just another spare LOL. Was a USB to USB extension over Cat5 cable and had the RJ45 straight into the switch, matter of minutes it was a lesson learned...

Not proud of it, but was funny.
 

ubercake

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You are pretty critical of a "Switch 101" summary on a web site. You want to read about home wifi routers and PoE in a "Switch 101" article that does a good job of bringing the definition of the basic functionality of a switch to people. Maybe you're looking for the wrong information in an article that clearly isn't called "here's how you connect and configure your entire home network 101".

This article sticks to the subject of switches and brings it down to a pretty understandable level for most people. It really is well organized and summarizes things at a general level.

I would think PoE and the like could be addressed in a 102 article that describes what else a switch is capable of and also get into topics on managed switches and their value.
 

ghavadi

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Router vs Switch.. That's what I wanted to read about.
you can't compare two different things.you only can compare layer 3 switches with routers.but still not the same functionality.
 

joex444

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You can easily compare a router and a switch. Switches have ports that are treated equally and do not have a DHCP server built into them. Routers have one port that is designated a WAN port, meant to connect to the Internet, and shares that connection to its LAN ports (and wireless clients) thanks to its built-in DHCP server.
 

joex444

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To be clearer, if you have a DHCP server *somewhere* on your network and you connect an Ethernet cable that ultimately connects to your DHCP server to one port of, say, a 5 port switch then the other 4 ports will automatically become DHCP clients of the DHCP server that is "upstream" via this 5th port. This is why connecting a desktop to a switch that is connected to a router also works.
 

ghavadi

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Hmm great point.But layer 3 switches like the Cisco 3750 you can create Dhcp-pools,and can work as a dhcp server.

 

falcompsx

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full duplex vs half duplex is not the cause / solution to collisions on a network. That is mostly caused by a hub vs a switch. Hubs function as repeaters, every packet of data that a port receives, is sent out every other port. This creates a lot of unnecessary traffic. On a switch, there is a MAC address table and every packet is routed to the port that has the destination MAC address connected and only to that port. Collisions occur when two devices are sending simultaneously and their transmissions "collide" causing a spike in voltage and the data is then destroyed. TCP/IP protocols handle this event by detecting the increased voltage and basically doing a reset(i'll not go into the specifics of how this happens, but it does). The reason a hub can cause this to happen and switches are almost immune to the problem is simple. Imagine you have a 4 port hub, if two devices transmit at the same time, bam, collision. If you replace that hub with a switch, assuming the two sending devices are sending to different recipients, the switch is smart enough to basically route the data to the correct port. Its almost like having a traffic light instead of an uncontrolled intersection. In an example with a 4 port hub, this doesn't really present a problem, but as you grow to a larger and larger hub with more and more connections, the problem grows exponentially and happens more and more frequently. Switches on the other hand, just keep on sending data only to one port or the other.

Back to duplex, assuming an ethernet connection, half duplex vs full duplex will NEVER cause a collision because transmit and receive are on seperate wires. The real difference between half and full duplex are bandwith. Full duplex is effectively double the bandwith of a half duplex connection. 100mbps half, can send, or receive at 100mbps max. Full duplex can send AND receive at 100mbps in each direction at the same time without any delays, so effectively you have 200mbps of bandwith. What is useful about this is for troubleshooting purposes, if you have a slow network connection, one of the first things to check is the negotiated speed. If you have a gigabit network, you should see 1gbps as your connection speed(1gbps is always full duplex, 1gbps half duplex doesn't exist in ethernet specs) if you see 100/half, you know something is wrong. Either a bad cable, driver, or some other issue is preventing your connection from negotiating properly at the maximum supported speed.
 

ubercake

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You don't even need a DHCP server running to connect devices to the internet through a router.
 

beetlejuicegr

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Nice article, i am having a very simple gigabit switch here at home but due to some PC relocation temporarily, my pc was stuck with the ethernet ports of the router. You can't imagine my frustration at working with 100Mbps. Hope they start making gigabit routers as a base. I wonder why they dont tbh.
 

Kewlx25

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full duplex vs half duplex is not the cause / solution to collisions on a network. That is mostly caused by a hub vs a switch.
Full-duplex cannot have collisions. The only reason hubs have collisions is because they cannot be full-duplex. Switches can have collision only when in half-duplex mode. So yes, collisions is a duplex issue.
 

trifler

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Indeed. Too many people jump on wireless without thinking. Wireless obviously has its conveniences, but one should not give up on wired for fixed location devices.

Another thing I find most people don't think of is that printers can be connected directly to a switch using Ethernet instead of using USB to connect to a computer. This allows all of your devices to use it without having to turn on the computer, as you need to with a USB connection. You also don't have to use network sharing. It's easy and convenient.
 

zodiacfml

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He has a point. Considering the audience here in TH are home users, the article does not touch on this Wi-Fi router and switch comparison. Many of us wouldn't need to purchase a switch if there's an existing Wi-Fi router already as the switch is only to expand the number of LAN ports. These days, wireless convenience trumps the performance and reliability of cable connectivity.

Router vs Switch.. That's what I wanted to read about.
you can't compare two different things.you only can compare layer 3 switches with routers.but still not the same functionality.
 

zodiacfml

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full duplex vs half duplex is not the cause / solution to collisions on a network. That is mostly caused by a hub vs a switch.
Full-duplex cannot have collisions. The only reason hubs have collisions is because they cannot be full-duplex. Switches can have collision only when in half-duplex mode. So yes, collisions is a duplex issue.
He is right. It is due to a hub device. You cannot buy a hub anymore which is why we don't have issues anymore with collisions. Switches/Wi-Fi routers are cheap enough these times. I was not even able to buy or touch a hub device ever. It could have one advantage though, over a switch, it doesn't need power or power adapters to work which can be useful in times where there is no easy way to get to a power outlet.
 

InvalidError

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Hubs aren't plain passive devices: they have a chip that takes the data from whichever port it detects incoming data from and then drives the data out on all TX pairs. Smarter hubs detect which port sent data first and then blank out all other ports until the current port's packet is done to reduce wire time wasted on collisions and jabber, almost guaranteeing that one packet will always get through.

For most intents and purposes, hubs died with 10Base-T some 15+ years ago.
 

jehanne

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Remember, the 7-layer OSI is a reference model; the 4-layer IP model is a protocol model. Unless you are a student preparing for the CCNA exam, it does not help "Joe 6-pack" much to discuss the OSI model. Ditto for Layer 3 switching (which, refers to the IP model and not the OSI one); a Layer 3 switch, in addition to switch frames (a Layer 2 function), also switches packets, a Layer 3 function typically done by a Router. A home router combines the router with a 4-port switch!
 

Ryangrant

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I'm finding that Link Aggregation is becoming more popular among small businesses and home users that do heavy media transfering over their LAN. Link Aggregation support is not supported on many of todays routers/switches and is something the consumer needs to look out for if they're wanting to consider aggregation on their network. The LACP protocol is a very popular one among the link aggregation community for consumers and businesses.
 

computertech82

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Missing the part where some switches are INTELLIGENT switches and have built in dhcp server (aka assigns ip address). A non-intelligent switch = no ip assigned, needs something else to assign them, or static ips.
Article all over the place. Makes something simple, hard........
 

willie nugs

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The only part of this article that I've read so far is the first section called "Network Switch Basics" and I feel fully qualified by now to say this article sucks.

Now I want to go write a proper Network Switch 101 article and submit it to tomshardware.com for publication.

I'm sorry for the harsh words, Eric Bliss. But this article truly does suck.
 

Flying-Q

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Top Picture - the blue shroud on the cable terminator is upside down.

The small hood on the shroud is supposed to cover the spring clip to prevent snagging and damage. Whoever made that cable is ignorant or incompetent or both. To use that picture as an exemplar at the beginning of the article sets the stage for the rest of the article. It rambled and digressed unnecessarly for a '101' style; it would have benefitted from being more structured as well as shorter and to the point. The first two sentences of the conclusion would have sat better in the introduction.

I have been an avid consumer of all things 'Toms' since the site's inception. Sadly, I have seen better descriptions of a switch from 15 year-olds in their IT class, this is not at the usual 'Toms' standard. Eric Bliss, I can see you have an articulate writing style, but this piece hints a lack of planned structure and appears rushed. Please get better.

Q
 

Kewlx25

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Thanks for the trivia knowledge. I never knew this. I wish my hubs did this back in the day. Playing Counterstrike on a LAN and someone starts doing a file transfer and the hub's collision light turned solid and ping shot up.
 

zodiacfml

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Top Picture - the blue shroud on the cable terminator is upside down.

The small hood on the shroud is supposed to cover the spring clip to prevent snagging and damage. Whoever made that cable is ignorant or incompetent or both. To use that picture as an exemplar at the beginning of the article sets the stage for the rest of the article. It rambled and digressed unnecessarly for a '101' style; it would have benefitted from being more structured as well as shorter and to the point. The first two sentences of the conclusion would have sat better in the introduction.

I have been an avid consumer of all things 'Toms' since the site's inception. Sadly, I have seen better descriptions of a switch from 15 year-olds in their IT class, this is not at the usual 'Toms' standard. Eric Bliss, I can see you have an articulate writing style, but this piece hints a lack of planned structure and appears rushed. Please get better.

Q
LOL. I missed that! I knew there was something wrong in that image.
 
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