Talk:Network switch/Archive 2

Clarification about the common use of the marketing term "switch"

To my knowledge generally when you're talking about a switch you're talking about a layer 2 switch. This is also known as a bridge or a workgroup switch. I think that although it is important to inform people that "switch" is really just a marketing term, and could mean one of many different pieces of networking hardware, it might be more useful to have the common definition somewhere in the first two paragraphs. I'm really not too sure on the specifics (workgroup switch = bridge = layer 2 switch?) so I will not edit it myself, but if someone has a good understanding of this topic, I highly recommend making this change. 74.14.228.158 17:44, 11 September 2007 (UTC)

I cannot agree that the general usage of "switch" is limited to layer 2. In older "switches", there were performance considerations that made layer 2 faster than layer 3, but, with such things as Ternary Content Addressable Memory (TCAM), the forwarding performance is as fast at layer 3 as layer 2. Layer 2 topologies also converged more slowly than a well-designed layer 3 system, and are limited by the spanning tree algorithm such that they cannot load-share multiple paths between two points (yes, I recognize inverse multiplexing can reduce this).

It may be worth considering how layer 2 "switches" began to differ from "bridges". The major initial changes were first microsegmentation, then full duplex Ethernet. Other functions came later, but they complement layer 3 techniques.

I strongly advise against making such a change in the first two paragraphs, based on 15 years or so of both implementing "switched" networks and designing network elements. I may use layer 2 only for cost reasons in a small network, but my small/home office network would not work without layer 3 as well as layer 2 elements, Howard C. Berkowitz 18:23, 11 September 2007 (UTC)

I agree that "in common usage" switch means ethernet switch. I suggest that this page is too broad.

I've boldly replaced technical discussion of CAMs in the introduction with "marketing terminology" explanation that already appears later in the article and is well supported by other linked articles within Wikipedia. I too have 15 years or so of networking experience including several years work in the IEEE 802.1 standards working group, the organization that likes to think they define these things.--Kvng (talk) 21:29, 2 August 2008 (UTC)

If a "network switch" page is necessary, perhaps it could refer as this page does to the concept of switching in networks in general, with separate articles referenced. Cisco here refers to "lan switching" http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/cs010.htm perhaps a page discussing the most common thing that people refer to in networking as a "switch" (a layer-2 ethernet switch) and what this is. Then there could be a page describing what is meant by "layer-3 switching" (which seems like a marketing term to me also) --Boscobiscotti (talk) 22:53, 8 January 2008 (UTC)

note about suspected copyvio.

I actually suspect that the page contains text copied from a printed source; however, that is only a hunch. The http://www.sencilo.com/network-switches.php site is mentioned in the {{subst:copyvio}} template only because it was what I found with a google search, not because I think that it's the original source. 69.140.152.55 (talk) 07:04, 13 June 2008 (UTC)

Evidence suggests the copyright violation was the other way around. Searching with the linked text, you find this paragraph:[1]

“ The network switch, packet switch (or just switch) plays an integral part in most Ethernet local area networks or LANs. Mid-to-large sized LANs contain a number of linked managed switches. Small Office, Home Office (SOHO) applications typically use a single switch, or an all-purpose converged device such as gateway access to small office/home office broadband services such as DSL router or cable, WiFi router. In most of these cases, the end user device contains a router and components that interface to the particular physical broadband technology, as in the Linksys 8-port and 48-port devices. User devices may also include a telephone interface to VoIP. ”

If you examine the history of the article, you can see that text develop organically. The first signs of that text come with this edit, where the contributor introduces the parenthetical "(or just switch for short)", in June of 2006. Much later, that was abbreviated to the current "(or just switch)", here. In May of 2007, the words "packet switch" were added to that string, here. Later that month, we see a new phrase emerging: "In the majority of cases, this is an ethernet local area network with dozens or more stations", here. This will later evolve into "plays an integral part in most Ethernet local area networks or LANs"--here,here, here and here. You can continue to see that paragraph developed, with some major additions including this, up to the point that it was moved further down the page into its present position, here. I have no doubt that this paragraph, at least, was developed on Wikipedia. --Moonriddengirl ^(talk) 14:54, 1 July 2008 (UTC)

Thank you for the thoughtful comment. Based on what you say, I tend to doubt that [2] is the original; however, I am suspecting that some of the content on the page was originally from a print source. This is a hunch. Without the source, I can't be sure. 69.140.152.55 (talk) 01:11, 11 August 2008 (UTC)

Circular use of "switch" and "router" as "marketing" terms

Under the "Role of switches in networks" section:

Again, "switch" is principally a marketing term; interconnection of different Layer 3 networks is done by routers.

Under the "Layer 3" section:

Router is a marketing term for a Layer 3 switch, ...

As stated this seems too circular to be helpful to anyone reading the article. Some kind of clarification or overhaul is requested.

-Onceler (talk) 18:00, 11 October 2008 (UTC)

... or is this circularity as clear, true, and accurate as can be stated? Ooh silence ... scary ... -Onceler (talk) 07:18, 1 December 2008 (UTC)

I have edited the Layer 3 section. Router is definitely not a marketing term for layer-3 switch - click the link and see for yourself. --Kvng (talk) 00:32, 3 December 2008 (UTC)

Thanks for your revision. -regards, Onceler (talk) 08:34, 19 December 2008 (UTC)

Marketing vs. technical terminology

Ethernet data forwarding entities as per the standards organizations that define these things:

• Repeater (802.3)
• Bridge (802.1)
• Router (IETF)

"Switch" does not appear in this list.

Types of "Switches" you can buy:

• "Switch" that is not 802.1D compliant. This is sometime given the technical designation "Buffered Repeater".
• A "Switch" compliant with 802.1D is typically seen as a multi-port Bridge.
• Many "Switches" feature varying levels of Router functionality in addition to their Bridging capability.

"Switch" can mean many things. It is not a precise term (I call it a marketing term). That's what I am trying to convey in my contributions to this article. --Kvng (talk) 16:55, 22 January 2009 (UTC)

collisions

Switch with 4 ports, for example: As the article notes, A & B can communicate (in full duplex even) without disrupting simultaneous communication between C & D, unlike a hub which merely repeats the raw signal from any node to all (other) nodes (so a hub can only have one node communicating in half duplex before collisions begin being observed by at least some nodes, although perhaps full duplex is possible if all but two nodes silently ignore everything?). But what about if instead, B & C both want to individually communicate with A (leaving D idle) using a switch? In such a case, will a switch repeat both signals (to A from B and from C) such that they collide, or will it cache and reorder the packets (to prevent any possibility of collisions)? And is this possibly what distinguishes a mere switch from a router? Cesiumfrog (talk) 05:52, 19 September 2010 (UTC)

Connections to a hub always operate half-duplex. On a switch, data sent from multiple ports to a single port will be buffered by the switch. If the pattern persists, the switch can run out of buffer space and packets will be discarded. --Kvng (talk) 06:15, 19 September 2010 (UTC)

Industry Analysis

This section simply makes no sense. It is very ungrammatical, but impossible to correct as its meaning and intention are obscure. Maybe somebody who knows what it's trying to say can help.

Section no longer exists. -—Kvng 04:23, 6 January 2013 (UTC)

Incorrect revenue figure

"There are currently 6 major players competing for market share of the $3.659 Billion Dollar networking and telecommunications industry. According to a Dell'Oro report for 1Q06 the market leaders in descending order are Cisco, Nortel, Hewlett-Packard, Foundry Networks, 3Com, and Extreme Networks."

This figure is obvious nonsense - Cisco alone has an annual revenue of $24 billion. Maybe the wrong thousands separator was used? Furthermore, using a currency symbol in combination with a currency name is redundant (both are commonly understood to refer to the United States Dollar). Other issues: capitalization and the fact that it doesn't state whether the figure pertains to the national (US) or international market. Maybe someone who has correct numbers could fix this, else it should be removed. Aragorn2 13:50, 24 August 2006 (UTC)

Statement no longer exists in article. -—Kvng 04:25, 6 January 2013 (UTC)

De-facto meaning

While WP drowns in technical details, the current article doesn't describe what's the difference between a switch, a hub and a bridge. The devices are different de facto, my CompTIA Network+ book (ISBN 978-0-7897-3796-0) claims that switches are smart hubs that redirect a traffic session only to the intended host. A bridge is, according to the book, more limited: it decides whether to block or let through data traffic from one network to another.

I think the intro and Function section are confused about the function. Functionally a switch is used as a junction connecting computers in a network, while a bridge is used to connect (usually only) two networks. Rursus dixit. (^mbork³!) 16:12, 7 August 2011 (UTC)

Clarifying myself: those things are mentioned, but not initially where they should be, and mostly drowning in techspeach ("operating at OSI 2 layer") obscuring the essence of the usage. The text needs shuffling, so that the article starts with the function and the usage, then the jargon can escalate step-by-step to make us nerds drool. Rursus dixit. (^mbork³!) 16:21, 7 August 2011 (UTC)

I agree that there is too much jargon in the lead. I do not, however, see any technical issues. The idea of a bridge as a two-port device dates back to when Ethernet networks were built with coax or Ethernet hubs. Now that these are gone, we have to update our terminology. The 802.1Q standard defines layer 2 switch behavior and "bridge" is the terminology used throughout. --Kvng (talk) 16:19, 11 August 2011 (UTC)

I agree that terminology has to be updated, but jargon sometimes evolves into common technical meaning different to the technical standards. Can a non-blocking packet switch be fairly described as a bridge, or even a switching hub? "Switching hub" is as obsolete as the original thin-net bridges -- and both terms belong in a history section instead of the intro. "Bridge" is still used to describe point-to-point wireless devices, which could be a useful comparison since they don't switch packets they just send them through to the other end of the link. A laymans description of the Layer 2 concept should still be in the intro because thats the core of its definition. Maybe intro could say: "Switches send data between devices physically connected to them, with basic ones being unaware of the data's final destination or internet address". Webwat (talk) 03:34, 13 October 2013 (UTC)

I think we'd all need to take a look on how these devices do their job – simply looking at what they do quickly blurs the distinction between repeaters, bridges and routers. What is commonly called "switch" is per definition (IEEE 802.3) a multiport bridge. What does a bridge do? A bridge takes a decision based on the destination's MAC address. A simple two-port device just decides whether it forwards a given frame or not. A multiport bridge makes this decision for each port it's got, essentially deciding where to forward it to.

In this line of thought, a repeater (hub) does not take any decision, and a router's decision is based on layer 3 information (commonly the IP address). Zac67 (talk) 10:16, 13 October 2013 (UTC)

Lead cleanup

Problems I have identified in the lead:-

1. It fails to summarise key aspects of what a "switch" is or does.
2. It contains too much technical information.
3. The lead is messy. For instance, it contains three or four different names for the switch.
4. Some of the content in the overview could be moved to the lead section to help summarise the subject.

Things I have done to correct this:

• Moved some of the technical content to the overview section, under a new subsection called Technical Details.

Things I recommend to be done:

1. Complete rewrite of the lead and to incorporate some of the content from the overview section.
2. Remove the many different names for the switch in the lead and maybe create a new (sub)section that explains the different naming.
3. The lead should give a general overview of the topic and avoid too much technical information. A little bit of technical information can be OK if it explained correctly, or can be understood by a broad audience.
4. Move the content outlining the difference between a switch and a hub to a new subsection.

--Hrbm14 (talk) 01:51, 5 February 2015 (UTC)

Hello! Well, the lead section clearly says that "a network switch [...] is a computer networking device that connects devices together on a computer network, by using a form of packet switching to forward data to the destination device" – please don't get me wrong, but how could that be made more understandable to Joe Averages? If we wanted even simpler words, we could only say that it's a device with multiple square holes one plugs some cables into, and all that just to be able to login into Facebook. :) The article is technical, that's what it is. — Dsimic (talk | contribs) 23:02, 10 February 2015 (UTC)

Hi,

Firstly, I would like to thank you for your feedback. I understand that this topic has to be inherently technical. My concerns was that the lead did not give a complete summary of the topic and, therefore, the technical content did not flow properly.

I have included a draft copy of a lead that might be better. Please feel free to make amendments as you see fit. The following things were changed:-

1) Removed "a form of". It is cleaner to write, "... Switches use packet switching" rather than "Switches use a form of packet switching". The words, "a form of" are, in my opinion, redundant.

2) Cleaned up the explanation relating to the "hub verses switch".

3) Other clean ups.

The revised lead is here. I posted it here to get feedback first.

A network switch (officially MAC bridge) is a computer networking device that receives, processes and forwards data to destination device(s) using packet switching. Unlike network hubs, switches only send the received data to the device that requests it. Multilayer (or layer-3) switches are those switches which have the capability of routing the packets based on IP addresses.

Ethernet Switches (sometimes also known as a switching hubs, bridging hubs or a MAC bridges) that operate at the data link layer of the OSI model process and forward Ethernet frames based on the source and destination MAC address stored within the header of the frame. The first Ethernet switch was introduced by Kalpana in 1990.. Switches also exist for various other types of networks including; Fibre Channel, Asynchronous Transfer Mode and InfiniBand.

Thanks, --Hrbm14 (talk) 01:51, 11 February 2015 (UTC)

You're welcome, and thank you for your contributions in the first place. Speaking of your proposal, unfortunately some of the details were lost in the process; for example, technically speaking, receiving device doesn't request or ask for anything to be forwarded to it, it's more about either the sending device initiating the forwarding of packets, or forwarding them due to the switch configuration. Also, we shouldn't limit the description to Ethernet switches, no matter how common they are. Went ahead and incorporated some of your changes into the lead section, together with some other improvements – please check it out. — Dsimic (talk | contribs) 06:55, 11 February 2015 (UTC)

References