WEBVTT 0:00:02.020000 --> 0:00:05.220000 In this video I'd like to show you how to actually configure switch virtual 0:00:05.220000 --> 0:00:09.360000 interfaces in a real Cisco switch and just a couple of ways you can monitor 0:00:09.360000 --> 0:00:12.400000 their effectiveness and see if they're working correctly or not. 0:00:12.400000 --> 0:00:16.280000 So those are the goals or objectives for this video to configure SVIs 0:00:16.280000 --> 0:00:21.260000 for IP routing and to monitor those SVIs for routing effectiveness. 0:00:21.260000 --> 0:00:23.500000 Let's go ahead and do that. 0:00:23.500000 --> 0:00:25.040000 So here I have my topology. 0:00:25.040000 --> 0:00:29.680000 As you can see here in the upper right hand corner I've got two hosts. 0:00:29.680000 --> 0:00:33.360000 Now in reality those hosts are routers but let's just pretend they're 0:00:33.360000 --> 0:00:37.120000 hosts. And they're already pre-configured with these IP addresses and 0:00:37.120000 --> 0:00:40.920000 subnet masks. I've got switch one. 0:00:40.920000 --> 0:00:43.700000 Switch one as you can see has already been pre-configured with a couple 0:00:43.700000 --> 0:00:51.940000 VLANs. So we have VLAN two which is on fast Ethan at zero slash one and 0:00:51.940000 --> 0:00:54.840000 that's what we see in the picture in the upper right hand corner. 0:00:54.840000 --> 0:00:56.120000 And we have another VLAN. 0:00:56.120000 --> 0:01:00.780000 VLAN three which is on fast Ethan at zero slash two. 0:01:00.780000 --> 0:01:05.640000 So my layer two connectivity, my layer two configuration has already been 0:01:05.640000 --> 0:01:07.380000 completed on the switch. 0:01:07.380000 --> 0:01:11.740000 All I need to do now is configure my switched virtual interfaces and get 0:01:11.740000 --> 0:01:13.900000 my routing to work. 0:01:13.900000 --> 0:01:15.840000 So step number one. 0:01:15.840000 --> 0:01:20.100000 I'm going to configure a switched virtual interface appropriate for VLAN 0:01:20.100000 --> 0:01:24.620000 two. So that would be interface VLAN two. 0:01:24.620000 --> 0:01:28.620000 That is a switched virtual interface and now it knows that whatever IP 0:01:28.620000 --> 0:01:33.920000 address I put in here is going to be in the same broadcast domain as VLAN 0:01:33.920000 --> 0:01:38.180000 two. So I'll use IP address two, two, two. 0:01:38.180000 --> 0:01:43.100000 Why don't we say one? 0:01:43.100000 --> 0:01:51.720000 No shutdown. Now we're going to repeat the process for VLAN three. 0:01:51.720000 --> 0:01:55.200000 Interface VLAN three. 0:01:55.200000 --> 0:01:58.000000 Put an IP address in that. 0:01:58.000000 --> 0:02:03.860000 3331 and the appropriate subnet mask. 0:02:03.860000 --> 0:02:13.660000 No shutdown. Now if we look in our running config, we will see those in 0:02:13.660000 --> 0:02:20.040000 there. Switch virtual interfaces are usually at the bottom. 0:02:20.040000 --> 0:02:23.120000 So you have to scroll through all of your physical interfaces first to 0:02:23.120000 --> 0:02:25.380000 see them. So there we go. 0:02:25.380000 --> 0:02:29.640000 We've got interface VLAN two and it is not administratively down because 0:02:29.640000 --> 0:02:31.760000 we don't see the shutdown command. 0:02:31.760000 --> 0:02:33.860000 And we see interface VLAN three. 0:02:33.860000 --> 0:02:37.980000 Notice we also have interface VLAN one which is the default switched virtual 0:02:37.980000 --> 0:02:42.100000 interface but I don't have any hosts in VLAN one so I don't need to put 0:02:42.100000 --> 0:02:43.860000 an IP address on that. 0:02:43.860000 --> 0:02:48.760000 Now one other thing I want to show you. 0:02:48.760000 --> 0:02:52.660000 Before we leave here, we want to make sure that these layer three switched 0:02:52.660000 --> 0:02:56.080000 virtual interfaces are actually up and ready to go. 0:02:56.080000 --> 0:03:02.820000 My favorite command for that is show IP interface brief. 0:03:02.820000 --> 0:03:07.280000 Here, your switch virtual interfaces show up at the top. 0:03:07.280000 --> 0:03:13.500000 And those one thing, both of them are in the up down state. 0:03:13.500000 --> 0:03:18.060000 Why is that? Well, here's something you need to know about switch virtual 0:03:18.060000 --> 0:03:22.620000 interfaces. Even though the switch virtual interface knows that it is 0:03:22.620000 --> 0:03:27.320000 part of VLAN two or VLAN three in this particular case. 0:03:27.320000 --> 0:03:30.920000 In order for the switch virtual interface itself to be up and ready to 0:03:30.920000 --> 0:03:37.260000 go, the broadcast domain like VLAN two needs to have at least one physical 0:03:37.260000 --> 0:03:42.140000 interface participating in that broadcast domain that is up and active. 0:03:42.140000 --> 0:03:47.260000 If VLAN two doesn't have any physical interfaces in it or if all the physical 0:03:47.260000 --> 0:03:51.680000 interfaces that are configured to be part of VLAN two are down, the switched 0:03:51.680000 --> 0:03:54.920000 virtual interface will also be down. 0:03:54.920000 --> 0:03:58.600000 And we can see right here, let's take a look at, well, I don't even have 0:03:58.600000 --> 0:04:05.240000 to look at show VLAN just by looking at this, actually not this command, 0:04:05.240000 --> 0:04:07.460000 show IP interface brief. 0:04:07.460000 --> 0:04:14.100000 You can see that all of my interfaces are administratively down. 0:04:14.100000 --> 0:04:18.400000 Some of these, well, for example, fast Ethan at zero one is in VLAN two, 0:04:18.400000 --> 0:04:22.120000 well, that's administratively down and fast Ethan at zero two, which is 0:04:22.120000 --> 0:04:26.000000 in VLAN three. That is administratively down. 0:04:26.000000 --> 0:04:32.020000 So there are no functional physical interfaces in these VLANs, which means 0:04:32.020000 --> 0:04:35.500000 my switched virtual interfaces can't come up. 0:04:35.500000 --> 0:04:38.180000 Now watch what happens. 0:04:38.180000 --> 0:04:40.920000 I'm going to go into my physical interface of interface fast Ethan at 0:04:40.920000 --> 0:04:44.560000 zero one. I'm going to issue the no shutdown command. 0:04:44.560000 --> 0:04:48.880000 And within seconds of doing this, not only will we see fast Ethan at zero 0:04:48.880000 --> 0:04:54.180000 one come up and become active, then we'll see my switched virtual interface, 0:04:54.180000 --> 0:04:56.140000 my SVI for VLAN two. 0:04:56.140000 --> 0:05:01.040000 In other words, interface VLAN two will also come up. 0:05:01.040000 --> 0:05:09.300000 There the physical interface just came up and we should see any moment 0:05:09.300000 --> 0:05:31.900000 now, the interface is going to be a little bit different. 0:05:31.900000 --> 0:05:35.260000 Well what's happening right now, why it's taking so long, there we go, 0:05:35.260000 --> 0:05:40.500000 is because not only does the physical interface itself have to be up, 0:05:40.500000 --> 0:05:44.660000 remember that physical interface of fast Ethan at zero slash one is running 0:05:44.660000 --> 0:05:46.680000 the spanning tree protocol. 0:05:46.680000 --> 0:05:50.040000 And spanning tree takes a little bit of time to figure out what it's going 0:05:50.040000 --> 0:05:54.080000 to do. Once spanning tree put that port into the spanning tree forwarding 0:05:54.080000 --> 0:05:59.880000 state, then my layer three switched virtual interface was able to come 0:05:59.880000 --> 0:06:02.700000 up. See watch that'll do the same thing. 0:06:02.700000 --> 0:06:06.960000 Interface fast Ethan at zero slash two. 0:06:06.960000 --> 0:06:14.680000 Now let's get this ready, show spanning dash tree interface fast zero 0:06:14.680000 --> 0:06:24.120000 slash two. Okay, no shut. 0:06:24.120000 --> 0:06:27.920000 Alright now we're going to see that the interface physically comes up, 0:06:27.920000 --> 0:06:30.640000 there it comes up right there the physical interface, but it's not in 0:06:30.640000 --> 0:06:33.060000 the spanning tree forwarding state yet. 0:06:33.060000 --> 0:06:37.940000 Right now it's listening, a few more seconds it will go into the learning 0:06:37.940000 --> 0:06:46.600000 state. Now it's learning and once it transitions from learning into forwarding, 0:06:46.600000 --> 0:06:51.260000 then we will see our switched virtual interface follow it and come up 0:06:51.260000 --> 0:06:56.980000 as well. So right about now it should be going into the forwarding state. 0:06:56.980000 --> 0:07:02.460000 There we go. We can see it's forwarding. 0:07:02.460000 --> 0:07:09.860000 So now my two switched virtual interfaces are up and ready to go. 0:07:09.860000 --> 0:07:14.520000 Now can I route between them? 0:07:14.520000 --> 0:07:22.820000 Well let's see. Let me go to host a. 0:07:22.820000 --> 0:07:28.020000 First of all let's do a debug ARP so that we can watch him ARP for his 0:07:28.020000 --> 0:07:29.480000 default gateway. 0:07:29.480000 --> 0:07:32.920000 He already knows that his default gateway is two two two one. 0:07:32.920000 --> 0:07:35.100000 That's already been pre-programmed. 0:07:35.100000 --> 0:07:38.240000 So I'm going to have him ping three three three three. 0:07:38.240000 --> 0:07:42.640000 As soon as I hit enter here, we should see him arping for his default 0:07:42.640000 --> 0:07:49.160000 gateway and getting an ARP reply. 0:07:49.160000 --> 0:07:53.540000 I may have turned off debug output. 0:07:53.540000 --> 0:07:56.780000 So hold on just a second. 0:07:56.780000 --> 0:07:59.140000 Let's see if he did it in the background. 0:07:59.140000 --> 0:08:03.840000 Okay well the debug did not display. 0:08:03.840000 --> 0:08:11.580000 Let me display that for you. 0:08:11.580000 --> 0:08:14.040000 Let's clear the ARP. 0:08:14.040000 --> 0:08:21.440000 Clear ARP. How about two two two one. 0:08:21.440000 --> 0:08:33.440000 All right. Well because we're dealing with Cisco devices here, if this 0:08:33.440000 --> 0:08:38.760000 was a real PC or laptop this wouldn't be happening but Cisco routers remember 0:08:38.760000 --> 0:08:40.700000 host A is really a Cisco router. 0:08:40.700000 --> 0:08:42.100000 It's not a host. 0:08:42.100000 --> 0:08:46.420000 When you do the clear ARP command, he tries to resolve it again. 0:08:46.420000 --> 0:08:47.760000 He says, oh yeah, really? 0:08:47.760000 --> 0:08:48.780000 You want to clear my ARP cache? 0:08:48.780000 --> 0:08:51.020000 Well I'm going to relearn it even if you don't want me to. 0:08:51.020000 --> 0:08:54.500000 So here we go. See two two two two that's host A. 0:08:54.500000 --> 0:08:58.760000 He's actually sending an ARP request for two two two one. 0:08:58.760000 --> 0:09:03.360000 And because two two two one is there, he receives an ARP response. 0:09:03.360000 --> 0:09:06.600000 So we see that because of the debug. 0:09:06.600000 --> 0:09:10.820000 But just because he knows who his default gateway is, does that mean he 0:09:10.820000 --> 0:09:13.120000 can now ping 3333. 0:09:13.120000 --> 0:09:20.500000 And the answer is no. 0:09:20.500000 --> 0:09:25.600000 Why is this? The switch has two switched virtual interfaces with correct 0:09:25.600000 --> 0:09:28.360000 IP addresses. They are up. 0:09:28.360000 --> 0:09:30.920000 They are responding to ARPs. 0:09:30.920000 --> 0:09:35.100000 It's because like I mentioned in the previous video, just because a switch 0:09:35.100000 --> 0:09:38.480000 has a bunch of switch virtual interfaces does not give him the permission 0:09:38.480000 --> 0:09:43.200000 or right to route between those switch virtual interfaces. 0:09:43.200000 --> 0:09:48.020000 We have to turn on IP routing in the switch to enable him to do that. 0:09:48.020000 --> 0:09:51.300000 So let's do that as our final thing right here. 0:09:51.300000 --> 0:09:53.560000 So let's go to switch number one again. 0:09:53.560000 --> 0:09:58.800000 IP routing. Actually, before I do IP routing, look at this. 0:09:58.800000 --> 0:10:03.640000 So before IP routing is on, if I type show IP route to look at the routing 0:10:03.640000 --> 0:10:06.820000 table, I see nothing. 0:10:06.820000 --> 0:10:08.960000 Routing table is empty. 0:10:08.960000 --> 0:10:15.380000 So even though I have IP addresses on this switch, there they are. 0:10:15.380000 --> 0:10:19.220000 They're connected to interfaces, which are up up. 0:10:19.220000 --> 0:10:25.860000 Those do not create connected routes in my routing table until I type 0:10:25.860000 --> 0:10:33.880000 IP routing. Now, my routing table is magically populated with connected 0:10:33.880000 --> 0:10:39.500000 routes. Now my switch knows he has permission to do routing. 0:10:39.500000 --> 0:10:45.760000 So now if I go back to host A and ping the remote destination, my ping 0:10:45.760000 --> 0:10:52.080000 is successful, which proves that my intervLAN routing, making use of those 0:10:52.080000 --> 0:10:56.760000 switch virtual interfaces, is functional. 0:10:56.760000 --> 0:11:00.820000 So I hope this video and this entire course on intervLAN routing using 0:11:00.820000 --> 0:11:04.920000 both router on a stick, as well as using switch virtual interfaces has 0:11:04.920000 --> 0:11:06.040000 been helpful to you. 0:11:06.040000 --> 0:11:10.280000 I really hope that now your mind is very clear on the differences between 0:11:10.280000 --> 0:11:13.680000 a VLAN and a switched virtual interface. 0:11:13.680000 --> 0:11:16.880000 A lot of people confuse the two and they're not the same at all. 0:11:16.880000 --> 0:11:21.460000 Remember, a VLAN is just the name of a broadcast domain. 0:11:21.460000 --> 0:11:27.580000 A switched virtual interface like interface VLAN is a layer three entity, 0:11:27.580000 --> 0:11:32.320000 a layer three host residing within that broadcast domain. 0:11:32.320000 --> 0:11:34.380000 They are not one and the same. 0:11:34.380000 --> 0:11:36.180000 So I hope this video was useful for you. 0:11:36.180000 --> 0:11:40.640000 And if you're using this as part of your CCNA pursuits, best of luck on 0:11:40.640000 --> 0:11:41.520000 getting your CCNA.