+Fr Robert Ballecer, SJ What is the difference between router and a switch? I 'm talking ab...

[G+_Bostjan Cadej]

 

 

+Fr. Robert Ballecer, SJ What is the difference between router and a switch?

 

I'm talking about home routers and switches, not those in enterprise einvironments. When does router the same work as a switch? DHCP is additonal service so this is not routers job, or is it?

What is the difference between router and a switch?

[G+_Ben Reese]

I don't dress quite as nice, but I'll try to answer your question.

 

First, there is little difference on the surface between an enterprise router or switch and home router or switch.

 

The confusion is understandable since most home routers have a 4-port switch built in, but they serve different purposes. The switch connects all the devices together physically, while the router tells the data how to get to it's destination. Both are needed to have a functional network, which is why home routers have switches built-in.

 

DHCP is typically a function of routers, but you're right that it doesn't have to be. If you turn off DHCP, you'll have to use another device for DHCP or use static IPs on all devices.

[G+_Fr. Robert Ballecer, SJ]

Good question... thanks for asking.

 

Here is a really, REALLY broad-strokes answer that's not COMPLETELY correct, but should at least let you understand the basic difference.

 

A switch routes packets WITHIN a network.

A router routes packets BETWEEN networks.

[G+_Daniel Armstrong]

I seem to recall watching a TWIET episode covering this.

[G+_Fr. Robert Ballecer, SJ]

Daniel Armstrong yup... a while back.

 

The basic principle is the same: route packets to where they should be. But once you get more than a few hundred (thousand if it's a high-end switch) entries, the table you need to keep to properly route the packets is just too big.

 

That why we have high-end routers and BGP: They can route packets in the right direction even if they don't know EXACTLY where it is.

 

Here's what a conversation would look like: (Again... EXTREMELY simplified)

 

Switch:

Sender: "Hey... I have a frame from "x" that needs to go to "y"."

Switch: ""y" is on port 3"

 

Router:

Sender: "Hey, I have a packet from "x" that needs to go to "y" on domain "a""

Router 1: "I don't know who "y" is, but I think domain "a" is on router 2"

Router 1: "Hey Router 2, I've got a packet from "x" that needs to go to "y" on domain "a""

Router 2: "Yeah... I've got domain "a", I'll forward to "y"

[G+_Dominick Valentic]

Fr. Robert Ballecer, SJ If I remember right a switch also likes to shout out those packets to every port as opposed to being a little more precise about it like a router

[G+_Ben Reese]

Dominick Valentic?, a hub will broadcast to every port, but a switch is supposed to keep a table of where everyone is. I suppose it will probably broadcast if it doesn't already know where you are.

[G+_Dominick Valentic]

Nope you're right....it was a hub I was thinking about....completely forgot about those ;P

[G+_Bostjan Cadej]

Fr. Robert Ballecer, SJ  Could you please explain this (router/switch) on the show.

By the way do you know what was like in the beginning of the internet, when there were no private IPs, like 192.168.x.x and so on? What was the role of router and switch then?

[G+_Michael Belew]

A managed switch could do similar things as a router. A router actually on the internet is more than a NAT router typically used at home. Using border protocols to find best routes for packets.

[G+_Steve Martin]

There is a very good description at https://goo.gl/QMauQS. The site is called ask Leo, but it isn't ”our” Leo.