Someone asked me today the difference between a router and a hub. I answered to the best of my knowledge but I'm curious if I got everything. So I pose you this question. What is the difference between just a normal hub and a router?

Generally, most define a hub as a device for connecting multiple ethernet devices into a single collision domain. A hub in itself is a layer 1 device in terms of OSI. Switches are hubs that can do simple "routing." I use the term routing very cautiously since it does not route in the typical sense. They "route" at layer 2 of OSI, or the MAC level of ethernet.

A "router" in the typical sense is a layer 3 device in terms of OSI. It routes data between logically disparate networks at the network layer and sometimes higher.

Now, those were the technical definitions. Layman's definitions are as follows. Hubs are used for hooking up more than a single ethernet device. Switches are souped up hubs. Routers are devices that relay data between networks. Residential NAT/Firewall/Routers generally have a built-in switch so a lot of people get confused and think they are switches.

-Weaver

Thanks Weaver. That's what I said it a Layman's term. Now next time someone asks me I can tell them the technical definition too (if they care).

just 2 add switch into the mix here we go.


A hub is typically the least expensive, least intelligent, and least complicated of the three. Its job is very, very simple: anything that comes in one port is sent out to the others. That's it. Every computer connected to the hub "sees" everything that every other computer on the hub sees. The hub itself is blissfully ignorant of the data being transmitted. For years, simple hubs have been quick and easy ways to connect computers in small networks.

A switch does essentially what a hub does, but more efficiently. By paying attention to the traffic that comes across it, it can "learn" where particular addresses are. For example, if it sees traffic from machine A coming in on port 2, it now knows that machine A is connected to that port, and that traffic to machine A needs to only be sent to that port and not any of the others. The net result of using a switch over a hub is that most of the network traffic only goes where it needs to, rather than to every port. On busy networks, this can make the network significantly faster.


A router is the smartest, and most complicated of the bunch. Routers come in all shapes and sizes, from the small four-port broadband routers that are very popular right now, to the large industrial strength devices that drive the internet itself. A simple way to think of a router is as a computer that can be programmed to understand, possibly manipulate, and route the data its being asked to handle. For example, broadband routers include the ability to "hide" computers behind a type of firewall, which involves slightly modifying the packets of network traffic as they traverse the device. All routers include some kind of user interface for configuring how the router will treat traffic. The really large routers include the equivalent of a full-blown programming language to describe how they should operate, as well as the ability to communicate with other routers to describe or determine the best way to get network traffic from point A to point B.

the power of google.although i knew this info i feel rather to google it then type it up.besides im not google.

Nevetheless, a very good description.

-Weaver

Simply a router is a managed switch that "routes" packets.

A switch 10/100 will allow every poart to connect at 100MB and transfer data as such.

A hub splits the bandwidth among the connections so if you have 5 connections on a 10/100 hub they get 20MB each.

robrowe wrote:

A hub splits the bandwidth among the connections so if you have 5 connections on a 10/100 hub they get 20MB each.

While theoretically this sounds logical, in practice it is far from the truth. This assumes that ethernet is 100% efficient. Anyone who understands ethernet knows this is not true. Ethernet's efficiency on a given collision domain is inversely proportional to the number of nodes on that collision domain. For those quick to retort, make sure you understand that efficiency != throughput the way I am using it here. Ethernet's CSMA/CD logic adds considerable overhead and kills efficiency as the number of nodes increases on a given collision domain.

-Weaver

OK Weaver now you have us all confused

While there are many factors to consider I was just trying to keep it simple. Nothing in this world is 100% efficient. If it were then perpetual motion would have been perfected and things would be much different.

For my home network I prefer to use a server as a gateway instead of a router. I seem to get better throughput that way then the rest of my network is connected to that server via a 10/100/1000 switch with GB uplink.

I am by no means a networking god but I try to do my best

robrowe wrote:

OK Weaver now you have us all confused While there are many factors to consider I was just trying to keep it simple. Nothing in this world is 100% efficient. If it were then perpetual motion would have been perfected and things would be much different. For my home network I prefer to use a server as a gateway instead of a router. I seem to get better throughput that way then the rest of my network is connected to that server via a 10/100/1000 switch with GB uplink. I am by no means a networking god but I try to do my best

I think you misunderstood the tone of my post. I apologize if you took offense to it. I never insult or try to make someone appear stupid on purpose, publically at least.

I believe you thought I was nitpicking at saying that your analysis of a 100 Mb/s ethernet being split up to 5 20 Mb/s chunks when 5 nodes are on the network was incorrect.

Yes, everyone knows that nothing is 100% efficient. However, ethernet is nowhere near efficient, especially when multiple nodes are on a single collision domain. I wouldn't have made the comment if ethernet was 95% efficient or even 90% efficient. Ethernet is terribly inefficient, usually around 60% and goes down from there when multiple nodes are on a single collision domain. Switching changes this, and the bottlenecks are usually the switches or NIC's themselves.

-Weaver

John, what the best connection that can be achieved with a wireless router?