Instructor: Now let's talk
about the VPC Reachability Analyzer.
So it's a really cool feature
because it's a network diagnostics tool
that helps you troubleshoot network connectivity
between two end points in your VPC.
So instead of having to dig through
the network configuration
and understand where the error is happening,
this builds a model of network configuration
between these two end points,
and then it will build and check the reachability
based on the configuration within your AWS accounts.
It doesn't not actually send back it
from source to destination.
It just analyzes your configuration
and tell you what's happening, which is very, very powerful.
So if we take an example of two EC2 instances, okay,
it says A and B.
They may be in different VPCs,
they have different ENIs
and they may have different security groups, okay?
And we're trying to figure out whether or not
Instance A can talk to Instance B.
So there's a bunch of things that need to happen, okay?
So first it goes from the Instance A to the ENI
then to the security group,
then to the network SCLs maybe,
and then to the security group
and through the ENI to Instance B,
and so all along the way,
this Network Reachability Analyzer Tool
from the VPC function is going to check
whether every single point is configured properly.
And in which case it will say, yes,
these two can communicate, they are reachable,
but in case they're not reachable,
for example, because of security group issue,
then it will automatically detect that one security group
will not allow traffic in.
And therefore your Instance B will not be reachable
from Instance A but all of this is done
by just analyzing network configuration,
not by sending packets.
So this is the idea,
and this is why it's super cool,
because he will tell you exactly.
Hey, your route table right here
is just not properly configured.
So the use cases for this is to do a troubleshooting of
connectivity issues and to ensure the network configuration
is made as intended.
So that's it for this lecture,
I hope you liked it.
And I will see you in the next lecture.