Occasionally we need to separate one type of traffic from another, perhaps
because the traffic belongs to different customers or one type is less secure.
One method of doing this is by creating additional routing
tables, which prevents the traffic from routing outside of its allowed area.
In the Junos world, this is done with routing instances
but you may be more familiar with the Cisco name, the RF Light.
Not everyone will have use this.
So let me give you a brief overview.
Routers have routing tables.
By default, they have one for each address family.
That's one routing table for IPv4, another for IPv6,
and there may be others, but will focus on IP v4 for now.
This routing table is known as the global routing table.
Using very
light, we can create additional virtual routing tables
and assign layer three interfaces to them.
We can also configure routing protocols to use them.
There are plenty of reasons while we might want to do this,
but for an overview, let's focus on just one.
We have an enterprise network which consists of servers,
workstations, printers, and other devices.
We also have need for an additional network
for third parties to install their equipment on.
Maybe this is to install monitoring systems for our air
conditioning or solar power or something like that.
We decide that this network should be entirely separate
from our regular network for security reasons.
Rather than buying all new Radisson switches.
We can use features like VLANs and via RF light relay
and separate traffic at Layer two by creating virtual LANs
and via flight separates traffic at Layer three by creating virtual routing tables.
While VLANs might provide some separation.
A router could easily pass traffic between VLANs.
But if we virtualize the routing table as well,
we create a fully separated virtual network
This is the base technology that service providers use to allow
multiple customers to use their equipment while still keeping them separate.
I understand this concept may be confusing.
I've compressed a lot of information into a very short time.
I have a video dedicated just to this topic,
so feel free to watch that first and then come back here.
The Juniper equivalent of the flight is called Routing Instances.
There are several types of these.
The most common of which are listed here are the types that match v RF Lot.
The closest are the no forwarding and virtual router type.
Both of these types create an extra routing table.
The virtual router type also creates a new forwarding table,
while the no forwarding type does not
release from a no forwarding instance
Going to the global forwarding table,
we might use a no forwarding instance if we want to run
more than one instance of, I don't know, routing protocol.
Unlike Cisco, Juniper does not let you run multi instance routing
protocols, but you can have one per routing instance.
We'll try this in the lab on the website if you want to see it in action.
The forwarding type is used with filter based forwarding.
You may know this by the name policy based routing.
The idea is that we use firewall filters to match certain traffic
and then apply different routing rules.
This is a clever way of bypassing the regular routing table.
Routing instances
are defined under the routing instances hierarchy.
We simply define a name and the instance type
We also add layer three interfaces under the routing instances.
We'll see the effect of this soon.
Config from other hierarchy areas can also go on to here
for example routing options so we can add a static route
to the routing instance.
Here's an interesting message
on this platform we require a license
to run the virtual Raza routing instance.
This is a warning message only.
So in the lab, this won't stop you from using them
to see a list of instances
use show route instance.
We can see the instance name and we can see that
it is the virtual routing type
We also see the name of the new routing table that is associated with it.
This is the name of the instance followed by INET zero
By adding the detailed keyword,
we are also able to see the interfaces associated with the instance.
If we want to look at the contents of this routing table,
we can use show round table followed by the routing table name.
This includes the direct and local routes that are created by adding an interface
as well as the static route that we configured
This is one of those cases where similar technologies exist
between different vendors, but they all have different names.
Try to get used to the Juniper names if you can,
especially if you want to pass the exam.
We've now reached the end of part four and we're nearly at the end of the series.
In the final part, we're looking at monitoring and troubleshooting
Juniper devices.
Click that video and I'll see you over there.