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Implementing Cisco IP Switched Networks (642-813 SWITCH) Tutorials
Basic Switch Configuration / LAB VLAN Trunk Setup pt. 1
Subtitles of the Movie (Implementing Cisco IP Switched Networks (642-813 SWITCH) / Basic Switch Configuration / LAB VLAN Trunk Setup pt. 1)
So in this next section of our lab, we're going to talk about VLANs and VLAN set up is pretty simple. You just go configure the VLAN interface and la di da, there's your VLANs. At least on switches, routers it's a little different but we'll get to that when we talk about Layer 3 Switching using an external router elsewhere in the course. In this section of the lab, we are actually going to set up some VLANs so that we can do VLAN Trunking and the VTP set up in the next section of the lab. And we'll also examine some of the commands that you use to set up VLAN Trunking and to make sure that it's doing exactly what you'd expect it to do. So right now, on all of our switches, Access and Core, we have a single VLAN. We have VLAN 1 which is the Default VLAN. If I go onto any of the switches and do Show VLAN, you see we have one Default VLAN, it's got all the ports in the VLAN except for the ones that are pointing at the other switches and no others. We've got the, the Default FDDI default and FDDINET and TRNET and all the other Default VLANs but really for the Ethernet side, we only have the one Default VLAN. Now some of the more astute among you may have realized looking at this VLAN listing here, that Ports 1 and 2 are missing from the Default VLAN. All the other ports are there, all the other 48 Fast Ethernet Ports and the 2 gig ports on this Access 2 Switch are there but what happened to Ports 1 and 2? Well the short answer is, those are Trunk Ports. Now, now how did you find that out? Let's say you looked at this and you said, well what's up with Fast Ethernet 1 and 2, why, why aren't they in there? Well you could go try to put those in the VLAN and it would tell you, hey that's, that's a Trunk or it would tear the Trunk down. But if we do Show Interface Trunk at this, we see that we actually have two Trunk Ports, Fast Ethernet 01, Fast Ethernet 02. The reason why we have these Trunk Ports set up automatically is that it is in Dynamic Desirable Mode. And if you'll recall from our discussion of VLAN Trunking, if one of your Switch Ports are in Dynamic Desirable Mode, then it will auto-magically build a VLAN Trunk whenever it detects another switch connected. And that's because again, on these Access Layer Switches, these Layer 2 Switches, the Default Port Configuration is Dynamic Desirable. If we do Show Interface Fast Ethernet 0 slash 1 and use this Switch Port Command here, we see that the Administrative Mode is Dynamic Desirable, the Operational Mode is Trunk. So the difference between these two settings is that's what's configured on the Switch Port and that's what the Switch Port is actually running at. For example if we do Show Interface Fast Ethernet 0 slash 6 Switch Port, it says that it is in Dynamic Desirable Mode. Operational Mode is down on this particular switch, in fact we actually have a machine connected to one of these. It's on Port 25, so we'll do Show Interface Fast Ethernet 0 slash 25, Switch Port. Now it's enabled, Administrative Mode Dynamic Desirable. Operational Mode Static Access and that's because there's a workstation connected to this, it's not getting any BPDUs, it's not getting DTP packets across this port, so it will not negotiate a Trunk across Fast Ethernet 0 slash 25. Now let's go up to the Core 2 Switch and we'll do Show Interface Trunk on this, you notice we only have the Fast Ethernet 01 Trunk up and running. But wait a minute, the two Core Switches are connected to one another, why isn't there a Trunk between those two switches? Well that's one of the differences between the Defaults on Layer 2 Switches and the Defaults on Layer 3 Switches. On this Layer 3 Switch if we look at Show Interface Fast Ethernet 0 slash 24, we see it's Up Up, that's not really the command I wanted to run. We run Switch Port, we'll see that the Administrative Mode is Dynamic Auto. Over here on the Core 1 Switch, Show CDP Neighbor to make sure that we're looking at the right port. In this case, Fast Ethernet 024 in this guy as well. We do Show Interface Fast Ethernet 0 slash 24 Switch Port. We'll see that the Administrative Mode is Dynamic Auto on this guy. So Core 1 and Core 2 are connected to one another, however because both of the Switch Ports are set for Auto Mode, they are in that goofy gopher mode is what I like to call it. Where each side is waiting for the other side to initiate trunking. So obviously with the Default Configuration with everything being in VLAN 1, this would work. It would send the traffic over this regular Switch Port, in this case you see that the Operational Mode is set to Static Access, even though it is connected to another switch, it would just flood the broadcast traffic across this link between Core 1 and Core 2. But when we define other VLANs on the Core 1 and the Core 2 Switch, the actual VLAN traffic would trunk through the Access Switches since there's not a trunk directly between those two Core Switches to get from one side of the network to the other. Obviously not something that you want to happen. So before we actually go define Custom VLANs or VLANs other than VLAN 1, we need to get this trunk running between Core 1 and Core 2. I'm running out of time in this video, so we'll pick up with this Trunk Configuration between the cores in the next video.
Tutorial Information
| Course: | Implementing Cisco IP Switched Networks (642-813 SWITCH) |
| Author: | Greg Dickinson |
| SKU: | 34304 |
| ISBN: | 978-1-61866-041-1 |
| Release Date: | 2012-04-20 |
| Duration: | 8.5 hrs / 102 lessons |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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