All right, so regarding the actual traffic flow and what's going on,
I always like to do a visual representation of that traffic flow.
So let's imagine that you and I are sitting at this VM at 10, 10, 0, 10.
The first thing it could be is, does this computer have a valid IP address?
So we check out the IP address on the platform we're at,
whether it's a Macintosh or it's a Windows computer or Linux verify its IP
address,
and also verify that it has a default gateway because we're trying to reach
something that's not on the local subnet.
So I'd verify, in this topology, for example,
maybe we're using .1 here at this gateway one. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
maybe we're using .1 here at this gateway one.
So it would go ahead and have a default gateway pointed to .1.
And then from a routing perspective, I just want to make sure that the routing
tables here on this gateway and the tier zero gateway and all the rest,
make sure that they all have a route, either a default route here or a
connected route here that lead to that 10, 90, zero address space.
I would also probably use a tool like Trace or some flavor of that, like Trace
Route,
just to verify the path that the packets are taking as they go through the
network.
And that way it can help us identify where it stopped. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And that way it can help us identify where it stopped.
For example, did it make it pass the gateway one?
Did it make it pass the tier zero gateway?
And that can also give us some clues about as far as how far it's making it
through the network.
We could also use the NSX manager as a tool to help us verify the path, for
example, to 10, 90, 0.1 and see the output there.
So let's presume for the sake of this discussion that the routing here on these
three gateways is all set up correctly.
The gateway on the client machine is also set up correctly.
So if those are all correct, what else could it be?
Well, if the client forwards the packet and going to 10, 90, 0, 1, it goes to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Well, if the client forwards the packet and going to 10, 90, 0, 1, it goes to
gateway one, it goes to tier zero.
And then it actually goes to this gateway up here, this router, then the router
is going to need to respond back,
assuming we're not doing that yet.
It's going to need to respond back to the 10, 10, 0, dot 10 address.
So this device right here is going to look at this routing table.
And it's at that point, unless we've actually set up specific routing
instructions on this router or are using a dynamic routing protocol.
I call it OSPF to train this router about how to forward back to these networks
.
That's very likely the reason we're not getting the responses back because this WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
That's very likely the reason we're not getting the responses back because this
router probably has a default route that goes out this way towards the internet
and doesn't have these specific routes going back to the 10, 10 network.
So to verify that we could go to this external router based on whatever
platform it is, Juniper, HP, Cisco, etc.
Take a look at that router and then take a look at the routing table and see
whether or not it has routes for the 10, 10, 0 network that would lead back
down in this direction.
And if it doesn't, we could then go ahead and fix it.
We're getting solutions. We could do static routes and say, hey, dear Mr.
external router to get to the 10, 10, 0 network. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
external router to get to the 10, 10, 0 network.
Go ahead and forward it down here to Gateway 0 to this IP address here on the
segment or even better yet, we could use OSPF.
So if we use the OSPF between here and here, we could train our tier zero
gateway to advertise these subnets, the 10, 10, 0 network and the 10, 20
network via OSPF through redistribution.
And that way this router right here would know, Oh, to reach the 10, 10 network
.
I need to send packets this way or to reach the 10, 20 network.
Again, I need to forward pack it this way at which point our tier zero gateway
would make the appropriate forwarding decision down to the appropriate tier one WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
would make the appropriate forwarding decision down to the appropriate tier one
gateway and then forward it down to the final destination.
And one other element it could be it could be that on these tier one gateways,
if we didn't check the box, it says, I want to go ahead and advertise connected
subnets up to the tier zero router.
That could also cause a problem because even if we redistribute tier one routes
on our tier zero gateway into OSPF, if these tier ones were never configured to
advertise those directly connected networks up to the tier zero, then we'd have
two problems.
This gateway zero wouldn't know how to reach the 10, 10, 10, 20 and our
external gateway would not have those routes either. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
external gateway would not have those routes either.
So thank you for taking a couple minutes to walk through this challenge with me
regarding a customer who didn't have full connectivity because of a lack of
routes because that gave us an opportunity to remind ourselves the importance
of
OSPF in an NSX to physical world environment and that is to share the routes so
that our routing tables are accurate, both on the NSX side and also on the
physical network side as well.
So again, thanks for joining me in a set of videos and also you my friend in
the very next skill.
Until then, I hope this has been informative and I'd like to thank you for WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Until then, I hope this has been informative and I'd like to thank you for
viewing.