Configuring Cisco Trunk Ports

hi everyone Roel D&E CEO here in this video we're gonna go over configuring trunk ports on a Cisco switch so this is my current network setup I have switch 135 50 which is connected to switch 2 which is a 2950 on port 24 on both switches I have them connected to each other and their Fast Ethernet ports this is the diagram I'm going to be working off of on configuring trunk ports so first off what is a trunk a trunk will allow multiple VLANs to transport between switches over that trunk link trunks can actually be configured in two ways either using the Cisco proprietary ISL or using the standard space 802 dot1q ISL as proprietary and the way it tags VLANs on to the ethernet frame and what it does is it takes the ethernet frame this is your original frame and when it's sending the frame across the trunk the trunk link it'll actually add a header at the front which is the ISL header and add in a new and a new trailer within the ISL header is where the VLAN number is place now with 802 that 1q the standard space it doesn't encapsulate encapsulate the frame and what it does actually is within the frame it'll insert a four byte tag and within that tag is the VLAN identifier so let's get it into configuring the trunk ports I'm currently console din to switch one and if I issue a show VLAN brief you can see port 24 is part of the default VLAN now if we take a look at that configuration for the port it's actually set to switch port mode access these commands were inserted earlier but what you can do is to verify if you have any ports in trunk mode right now you run a show command show interfaces trunk and it came out blank because I don't have any trunk active trunk ports so we'll enter interface configuration mode for poor 24 and the first thing you want to configure for 802 dot1q is the encapsulation mode and that's done by issuing switch port trunk encapsulation if you hit the question mark we have dot1q ISL or negotiate those are our three options and we're gonna stick to 802 dot1q because that is the standard I don't use ISL in my networks and you shouldn't either I would stick to 802 dot 1 q now negotiate means it'll automatically negotiate a trunking encapsulation with the other side or the far end of the cable that is another option I don't use I like to statically set my options so we'll type in so a sport trunk encapsulation dot1q now that sets the encapsulation mode for the trunk interface but that doesn't actually turn on trunk mode now to do that you issue switch port mode trunk and that's it for configuring port 24 as a trunk interface now a couple of things to notice is now if you issue the show VLAN brief command again port 24 is no longer in that list and that is because the show VLAN command will only display access ports and not trunk ports if we issue the show interfaces trunk command now we're showing that port 24 is on for trunk and the encapsulation is 8:02 dot1q its current status is trunking it's allowing VLANs one through 4090 for native VLAN is VLAN one by default so now we'll configure the far-end so now I'm console then to switch to and if we do a show VLAN brief command interface 24 is part of the default VLAN one we'll do a show run interface port 24 and it is actually configured as an access port we'll see if there's any trunk ports on the switch by issuing show interfaces trunk and we have none right now so let's go into global configuration mode go into interface configuration mode for port 24 with interface Fast Ethernet 0 / 4 and since this is a 2950 switch if we try to set the encapsulation mode and I'll hit question mark in the command is unrecognized and that's because with this switch 802 dot1q is the only encapsulation mode we can use so you can actually bypass this command and go straight into switch port mode trunk to make it a trunk and for good measure we can disable negotiation by doing running switch port no negotiate so now if we do a show VLAN brief again to verify 4:24 is no longer on VLAN ones default VLAN run a show run interface fastethernet 0/0 to see its configuration it is configured as a switch port mode trunk verify again with show interfaces trunk command and we can see that port 24 is on with using encapsulation 802 dot1q it's trunking on native VLAN 1 and these are the VLANs that are allowed to transport through this trunk link and there we have it we've configured two switches with with the trunk between the two switches trunk link and now VLANs can't multiple VLANs can transport between these two switches [Music]

Channel: Rowell Dionicio

Views: 134,098

Rating: 4.8648648 out of 5

Keywords: cisco, trunk port, configuration, ccna, 200-120, ccnp switch, 642-813

Id: uU1CRuuSBQo

Length: 8min 1sec (481 seconds)

Published: Tue Nov 26 2013