VLANs and Trunks for Beginners - Part 1

okay this tutorial is going to be about VLANs and trunks now I'm using packet raiser here and I've got a switch out here and I've got two clients and basically a switch is used to create local area networks or lands and it's used to interconnect pcs on a LAN right so you've got this PC at 192 168 1 dot 100 and this PC at 192 168 1 dot 101 and we're going to connect both pcs to this switch and then they'll both be on the same local area network so I'll take the cables and I'll cable this switch right here we'll put this guy into port let's say five and we'll put this guy into port fast ethernet click and then we'll put this guy on port 10 so now both pcs are on the same land and they can talk to each other so if I go into PC 101 here open up a command prompt I can ping I can ping the other PC on at 1 dot 100 right I can send an echo request and get an echo reply we're on the same local area networking we could communicate partially because we have the same network address space now what we can do is let's take a look at this switch and start talking about VLANs and trunks so first of all the Cisco switches are set up by default so that every port on the switch is already part of the default VLAN which is VLAN 1 so that means if we go into the switch and we'll go into the CLI command line interface and we'll type enable and we'll go to we'll do show VLAN as a command from the privilege user mode you'll be able to see that by default with the show VLAN command that VLAN 1 is the default VLAN it's active and notice all the ports on the switch are all part of VLAN 1 right and then you can see we've got some other built-in default VLANs here we've got VLAN 1,002 1,003 4 & 5 & 2 is for FDDI 1003 is for token ring and then you've got another FDDI and another token ring and these are therefore basically backwards compatibility with these older forms of networks right and you cannot delete these these are the defaults so you cannot rename VLAN 1 it's always going to be the default VLAN and you cannot delete VLAN 1 and same goes with these other VLANs now so these are the built-in VLANs that come ready to go on the switch so if you just plug your PC into the switch you're already part of the default VLAN and all of the ports are assigned to VLAN 1 so what we can do is is we can create additional VLANs so what we can do is we can say compte short for configured terminal go into global config mode and we can say VLAN 50 right and then now notice we are in config - VLAN we're in VLAN configuration mode and now we could say look at the commands that are available you can see name is available also the no command to get rid of the VLAN but we'll give it a name so we'll say name we'll call it student right so there we go we've got now name student we have a VLAN 50 and it's named student we can also do another one let's say VLAN 99 right and we could say name and we can call this one mgt for management so now we've created a VLAN for let's say management all right and let's exit and we'll do a show run I didn't want to do that let's do a show VLAN and now you can see that we've got the 50 student VLAN and the VLAN 99 the management VLAN now and they're both active but no ports are assigned to them right so the next thing to do once you have created a couple of VLANs is maybe to assign them to supports so what we'll do is we'll say we'll put this PC right here 101 who is on port 10 we'll put him we'll make port 10 part of the student VLAN and let's see what happens if we do that so we'll go like that and we'll say interface FA well first we need to go to configure terminal or compte for short to get to global config mode then int tab just short for interface FA tab which is short for Fast Ethernet 0 / now we're in interface configuration mode right and we'll say switch tab switch port mode access can make it an access port all right as opposed to let's say a trunk port which we'll be talking about in a minute and then we'll say SW tab switch port access VLAN 50 okay so now we've just assigned that port to that VLAN now let's say end here and I'll do a show run tab oops show run tab which is running config and you can see now that port 10 is now part of VLAN 50 right switch port access VLAN 50 switch port mode access right so now port 10 is on a different VLAN then port 5 which is part of the default and you'll see here let's do one more we'll do a show VLAN and you can see that now VLAN 50 has port 10 assigned to it right now if we go back to our two pcs that have the same IP address range 1 dot 101 dot 101 they will not be able to communicate with each other because this port port 5 is in VLAN the default VLAN which is VLAN 1 and this port port 10 is in a VLAN that we just created called the student VLAN so we'll do that same test and we'll see that it fails right I'll go to ping 100 and you'll see that now I'm unable to communicate with the other PC because I'm on separate VLANs right so when you assign VLANs to switch ports different VLANs you're basically taking the switch and creating separate lands hence the name VLAN or virtual land right so instead of just one local area network where all the the PCs can plug into the switch and communicate with each other it's as if right now these two switches are on separate networks so if this PC is on VLAN 50 it's going to be more appropriate for maybe scipy address to be 192 168 fifty dot 101 and so we can do that just to show that in fact this PC is no longer on the same LAN as the other PC so I'm going to do that and change its IP address to 50 dot 100 since they can't communicate anyway what's the point of having them in the same IP address range they're essentially on separate networks because they're on separate VLANs once again this is here the default VLAN which is VLAN 1 and now he's on VLAN 50 so they're on essentially two separate networks and they're unable to communicate now they could communicate with each other with the presence of a router to route across the switch between the two separate networks or if we had a layer 3 switch which could basically handle the routing itself from within the switch but we don't this is a layer 2 switch and it's got separate VLANs now it's got ports on separate VLANs so the 2 pcs are unable to communicate

Channel: danscourses

Views: 2,146,002

Rating: 4.87918 out of 5

Keywords: VLAN, trunk, Cisco, CCNA, configure, beginner, how-to

Id: aBOzFa6ioLw

Length: 9min 9sec (549 seconds)

Published: Sun Feb 05 2012