Ccna routing and Switching Complete Study Guide

sh interfaces gi0/1 trunk

 

Port        Mode         Encapsulation  Status        Native vlan

Gi0/1       auto         negotiate      not-trunking  1

[output cut]

Sure enough—the port is not trunking, but we already knew that. Now we know it 

again. Notice that we can see that the native VLAN is set to VLAN 1, which is the default 

native VLAN. This means that VLAN 1 is the default VLAN for untagged traffic.

Now, before we check the native VLAN on S2 to verify that there isn’t a mismatch, I 

want to point out a key fact about trunking and how we would get these ports between 

switches to do that.

Many Cisco switches support the Cisco proprietary Dynamic Trunking Protocol (DTP), 

which is used to manage automatic trunk negotiation between switches. Cisco recommends 

that you don’t allow this and to configure your switch ports manually instead. I agree with 

them!

Okay, with that in mind, let’s check out our switch port Gi0/13 on S1 and view its DTP 

status. I’ll use the 

show dtp interface 

interface

 command to view the DTP statistics:

S1#