Sunday, 8 September 2013

Info on DTP ( Dynamic Trunking Protocol)!

Heyaa everybody, your Sunday night post is ready!!

It's time to talk about DTP. As the Title says DTP is Dynamic Trunking protocol. This is a Cisco Proprietary protocol. I will try to explain this in a very simplistic way.

This is a protocol which runs between all the connected ports with access or trunk mode to negotiate the other side port to be in Trunk or in access mode. Here are the modes, you wanna have a look :-

1) switchport mode access - DTP flows and tells the other side, DO NOT NEGOTIATE TRUNK LINK. This port will never change itself to trunk even if the other side is in disagreement.
2) switchport mode  Dynamic desirable :- This is the default value of all the ports in the Cisco switch. It tells the other side to negotiate trunk. It will successfully convert the itself  to trunk if the other side port is in AUTO, DYNAMIC DESIRABLE or Trunk.

3) Switchport mode Dynamic auto - This is an Useless command NEVER USE IT!!! It tries to make the other side trunk link if the negotiation fails, it becomes non-trunk.

4) Switchport mode trunk -  Makes the link trunk, requests neighbor port to become trunk, if the other side doesn't agrees it remains in trunk mode. Alll this information lies in DTP packets.

5) Switchport nonegotiate - Stop from Generating DTPs. You must use this command in Access or Trunk port mode. Useless command.

Here is hierarchy of DTP values :-

Reference :-

No comments:

Post a Comment