[AUDIO LOGO]
Hello, and welcome to Implementing L3 VPN
advanced features.
So we've already gone through all the basics
of getting L3 VPN up and running in our environment.
But now, we want to jump in and take a look
at some modifications that we can make to this environment,
if we have a need to do so.
So the first thing we're going to do
is jump in and take a closer look at penultimate hop-popping
or PHP operation.
This is where the next to last router
actually removes the forwarding label because the egress PE
theoretically doesn't need that forwarding label
to get to its own loopback.
This can, however, have some unintended consequences.
So we're going to look at those details.
Then we're going to take a look at TTL propagation.
When a packet comes in to the MPLS environment,
the default behavior is to copy the TTL
from the original packet onto the newly created label.
This is not always desirable behavior, however,
because if a customer does a trace through our environment,
they'll get to see all of the P routers in our core,
and that might not be desirable.
Then, we'll take a look at something called route leaking.
There are occasions, where we might need routes to actually
go from one VRF to another, either maybe
between customers or between different departments
at a company, maybe.
Or it would also be another way to possibly implement
central service VPNs.
So there's a couple of reasons we might want to do this,
but we're going to want to do it in a controlled fashion.
And finally, we'll wrap up with looking at conditional label
advertisement or what we would generically call label control.
We'll take a look at how we can control
which labels get advertised to peers for which prefixes,
as well as which labels we're accepting
for which prefixes from peers.
So again, we can either filter outbound or inbound.
So as you can hear, we've got some pretty cool stuff
to cover here.
Hopefully, you'll find this entertaining.
Let's go ahead and jump in and get started configuring
all of these things.
And I'll see you in the next video.