Another copper cable you may come across a direct attachment cable or DAC cable the cable comes in various
lengths up to 15 meters use as copper twinax and has a set piece on each end.
And SFP or small form factor pluggable is a hot pluggable transceiver and may support various media
types such as fiber or copper.
This replaces X or kickabout interface converters and the one shown here is an enhanced small form pluggable
or SFP plus that supports data rates up to 10 gigabits per second.
So a deck cable is inserted into an SFP plus slot and allows for a 10 gigabit per second connection
between two devices on the PS or SFP Plus's will support fiber that can go to great lengths.
But this cable allows for 10 gigabit copeck connectivity between two devices over a short distance such
as seven meters a roll over cable is a special cable used to connect to the consuls of networking devices.
It allows you to connect from the serial port on your PC or laptop to the console of a router or switch.
So if you've got a serial port or comport on your PC you can connect directly to the console of a Rotto
a switch using a rollover cable.
However a lot of modern day PCs don't have serial ports so you'll need to get a USP to serial port converter
which has a USP connection on one side and a D-B nine male connector on the other side.
This would allow you to connect a D-B nine female console cable to your PC with either a Arjay 45 connector
on the other side or another D-B 9 connector.
Most Cisco switches and routers use an RJ 45 connector but you may come across some devices from other
vendors such as HP that use a D-B 9 connector for the console port.
So a DC 9 serial would connect to your PC and either an RJ 45 or nine serial would be connected to the
console of the networking device that you want to configure in a rollover cable.
All pins are inverted or rolled over.
So pin one is connected to pinot pintu is connected to pin 7 3 to 6 and so forth and so on until you
get to pin 8 which is connected to pin 1.
You could use a standard cat 5 a cat 6 cable as a rollover cable and then just change the peanuts on
the ends from straight through to rollover.
But typically this is not required as most networking devices are shipped with console cables.
This video has explained a lot about Ethernet and data flows in the next video.
We'll look at how traffic is forwarded by Hubbs bridges switches and routers
in
now that we've looked briefly at cabling I'd like to explain how networked devices operate.
And the first device that we're going to look at is a hub a hub is a layer one device in the overside
model and you would use a cat 5 unshielded twisted pick cable with an RJ 45 connector to connect your
laptop as an example to a port on a hub.
Hubs aren't very popular today and have been superseded by switches and I'll explain in a few minutes
why.
But for now let's assume that you are connecting your PC to a hub.
It's important that you understand how a hub operates however because the wireless operates in the same
way like a physical hub would.
So when you connect to a wireless network you'll often encounter the same issues that you would encounter
when connecting to a physical hub.
So for now let's assume that you are connecting your PC physically to a hub hubs have multiple ports
and thus multiple devices can be connected to a hub at the same time.
The number of ports available depends on the hub model.
But as you can see in both of these examples a hub has various ports that you can connect devices to.
So in this topology let's assume that you have four devices connected to a hub on ports one to four.
It's important to realize that a hub is a physical layer device.
It's not intelligent and does not understand the frames going through it.
It's basically a multi port repeater and it will amplify or repeat the frames that it receives on one
port.
Out of all other ports.
So it's once again simply a multi port repeater with no intelligence.
The physical topology of a hub is a star topology in a star topology you have a central device which
in this case is a hub and devices hanging off that central device as spokes which resemble the spokes
in a bicycle wheel.
Each spoke device is connected to the central device with its own cable and all transmission or communications
between devices or through the central device.
In other words if he wants to communicate with C the traffic will flow through the hub and will not
flow directly between the two devices.
They were some major advantages to using hubs and UDP rather than 10 base two.
The first advantage is a cable break if a cable broke.
In this typology it would only affect device a.
And it would not affect the rest of the network in 10 days.
2 If a cable broke it would affect all devices in that network here.
However other devices such as C and B can still communicate even though the cable is broken to device
say.
Another advantage is that you can extend distances easily.
A bus typology is limited in size in a 10 base t environment such as this.
The distance between a device such as A and the hub needs to be 100 metres but you can extend the distance
by adding another hub.
In other words you add a nother multi-port repeater and repeat or regenerate the signal to extend the
distance of the network to distances greater than 100 meters.
So in this example E could be one hundred meters away from its hub and the two hubs could be 50 meters
apart.
So in this example we've extended the network further then the restriction of 100 meters.
So a device E could be 100 metres from its hub it could be a cable length of 50 metres between the two
hubs and a could be 100 metres away from its hub a network now has a length of 250 metres which is well
over the limitation of 100 meters.
Now there are restrictions on the number of hubs that you can daisy chain together.
But the point is it's possible to extend that apology by adding more hubs and more devices to the network.
These were therefore great reasons to move away from 10 base to and 10 base 5 and implement a UDP or
untrusted pay networks using hubs.
Another advantage is that UDP cabling is cheaper and easier to manage and therefore it became common
to use hubs and 10 base T rather than 10 base 2 or 10 base 5 in the past.