-: Network redundancy.
Network redundancy is focused on ensuring our network
remains up and running at all times
to increase it's availability.
This includes the servers connections
to the network, the connections between our switches
and our routers, and our connections to the internet.
To accomplish this,
our servers often have two or more
network interface parts,
and they can be operated as a pair
or in a low balancing configuration.
In this example,
I have a network with five network cards installed.
You can see that there's currently four network cables
currently plugged into it.
This way, if one of those cards fails,
the other ones can take over the load
and the demand.
Now this can paired for redundancy,
or you can split them
and put them into two groups
so you can have additional throughput
by operating more than one at a time simultaneously.
In this example I might create two groups,
one with four network cards in it
and one with a single network card by itself.
That gives me the total of five.
Four network cards can operate in a shared load capacity,
meaning that all four will work together.
So if they were each 100 megabytes per second each,
that gives me a combined
400 megabytes per second,
but that fifth one is sitting there by itself
and it has 100 megabytes per second to use.
We use that as our backup redundancy.
So if those four went out,
that fifth one could take over,
even though it's a slower conenction.
Now to ensure our network devices have redundancy
we often use switches or routers
that are configured with multiple
and redundant network cables going up between them.
For example, I have a switch here with
two trunk ports using fiberoptic cables.
This allows me to have that switch be able
to get service from two separate routers.
And so if one router goes down
the other router can take over as the secondary
and then carry all the data from that switch
out to the network.
This gives me redundancy by allowing
us to have different pathways
out for that switch.
So, as you can see, when you're planning
for network redundancy
you need to think about it in three parts.
You need to think about it as the device,
those network interface cards and those cables.
You also need to think about it from the
switches and routers perspective
to make sure you have redundant paths inside the network.
And you need to think about it from the internet connection.
And making sure you have
redundant paths out for that as well.