All right, let's go ahead and answer some questions about software defined
accesses or
relates back to these overlay technologies we've been talking about, especially
LISP
and VXLAN.
So again, SDA is going to run using these protocols and we're trying to build
something a little
bit better than just straight up layer two to the access layer or layer three
to the
access layer.
Keep in mind when we see an SDA fabric topology like this, these are going to
be access layer
switches.
There are switches that exist inside our access closets, inside our networks, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
There are switches that exist inside our access closets, inside our networks,
and then we
have real hosts, real people, real, well, maybe the people don't connect to the
network,
but they're laptops, they're desktops, printers, access points, all of these
access layer
devices, phones, by the way, if we have voice over IP phones, all of these
would be connecting
in via these switches.
So question number one here, what type of network exists between switch one and
switch
two?
What is going on in here?
Well, this is a layer three network.
All of these are going to be layer three endpoints, so we are routing in this WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
All of these are going to be layer three endpoints, so we are routing in this
domain.
We can run a routing protocol like OSPF or EIGRP, but either way, we are
scaling out
at layer three here, and regardless of how many edge switches we have, they're
all going
to connect to one another at layer three.
So what type of tunnel is built between switch one and switch two?
Well, at this point, we know that we are building a VXLAN tunnel.
We're not deploying a LISP tunnel because LISP tunnels are layer three, but we
are going WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
are going
to instead use VXLAN to form layer two over layer three using these tunnels.
It's a wonderful technology, came out of the data centers we talked about, and
now we're
using it for SD access.
So next, if switch one doesn't know where host B lives, what will it do?
Well, this is where LISP starts to get involved.
If we didn't have a control plane protocol, we would just have to flood it out
not only
to switch two, but potentially to all kinds of other switches until we learned
where host
B lived. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
B lived.
Instead, we don't have to worry about that.
I can use LISP to go to the control plane node.
The control plane node is going to keep track of all of these hosts.
And remember, from a LISP perspective, that's the responsibility of the MSMR.
Now we're not going to use LISP terms with software defined access.
Instead, we are going to call this a control plane node.
So I'm going to go to the control plane node and I'm going to pull down the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So I'm going to go to the control plane node and I'm going to pull down the
information.
So now I know where host B lives.
Host B is connected to switch two.
And so I'm going to send it out the VXLAN tunnel that is built that I have
built with
switch two.
Now again, if it does already have this information, so when the next packet
arrives, I don't
have to worry about this process.
I don't have to go through this twice.
I will eventually have, I mean, I'm putting this information into a cache.
I will eventually time that cache out that entry and I will drop that. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I will eventually time that cache out that entry and I will drop that.
But if the entry is still in my cache and I receive another packet, first of
all, I'm
going to refresh the cache timer, make sure I don't expire data that's actively
being
used.
And I'm just going to send it straight into the VXLAN tunnel.
And so this control plane mechanism of LISP is going to work wonderfully with V
XLAN in
order to enable our campus fabric.
Just keep in mind in all of this that LISP works for the control plane and VX
LAN works
for the data plane.
But we do still have that policy plane that's managed by ICE and especially WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But we do still have that policy plane that's managed by ICE and especially
Cisco trussec.
So this is how all of these protocols come together.
And again, why Cisco really wants us to understand how LISP and VXLAN operate.
We are expected to understand how exactly they operate independent of software
defined
access.
But I really wanted to bring this back together at the end to say, okay, now
that we know how
they work, why do we care?
We have to understand why we care.
And at the end of the day, we care because Cisco is deploying these
technologies actively WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
technologies actively
in software defined access.
I hope this has been informative for you and I'd like to thank you for viewing.