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Cisco CCNP / BCMSN Exam Tutorial: Dynamic Trunking Protocol (DTP)

When you are studying to pass the BCMSN exam on the way to earning your CCNP certification, you are going to add to your CCNA knowledgebase every single step of the way. Nowhere is that far more than configuring a trunk amongst two switches. You know that IEEE 802.1Q ("dot1q") and ISL are your two selections of trunking protocols, and you know the main differences between the two. What you may well not have known is that there is a third trunking protocol that is running between your Cisco switches, and even though it is a transparent method to many, you had far better know about it for your BCMSN and other CCNP exams! The Cisco-proprietary Dynamic Trunking Protocol (DTP) actively attempts to negotiate a trunk link with the remote switch. This sounds excellent, but there is a cost in overhead - DTP frames are transmitted every single 30 seconds. If you decide to configure a port as a non-negotiable trunk port, there's no need to have for the port to send DTP frames. DTP can be turned off at the interface level with the switchport nonegotiate command, but as you see below, you cannot turn DTP off until the port is no longer in dynamic desirable trunking mode. (Dynamic desirable is the default mode for most Cisco switch ports.) SW2(config)#int rapidly /8 SW2(config-if)#switchport nonegotiate Command rejected: Conflict in between 'nonegotiate' and 'dynamic' status. SW2(config-if)#switchport mode ? access Set trunking mode to ACCESS unconditionally dynamic Set trunking mode to dynamically negotiate access or trunk mode trunk Set trunking mode to TRUNK unconditionally SW2(config-if)#switchport mode trunk SW2(config-if)#switchport nonegotiate When you're operating with Cisco switches in a residence lab or rack rental atmosphere, run IOS Assist often to see what possibilities are accessible for the commands you are practicing with. Cisco switch ports have rather a few choices, and the greatest way to find them is with one particular basic symbol - the question mark! worth reading