DTP Flashcards
When running “show int trunk”, what does the output “n-“ designate?
The encapsulation type (ISL or 802.1q) was auto-negotiated.
What are the two DTP modes?
Auto and desirable.
How do you turn off DTP?
Switchport mode trunk, switchport nonegotiate
Briefly describe DTP.
Dynamic trunking protocol. Attempts to form trunks by sending a DTP frames out desirable ports.
Is DTP industry standard?
No, it is Cisco proprietary.
How often are DTP frames sent?
Every 30 seconds.
DTP is a security risk because it allows the introduction of ___ into your network.
Rouge switches.
What is a good command to use to check a trunk’s DTP status?
Show interface switchport. Look for the “Negotiation of Trunking” field. Use the pipe modifier.
What is a good command to use to check a trunk’s DTP status?
Show interface switchport. Look for the “Negotiation of Trunking” field.
If a switch supports ISL and 802.1q, what must you do before you can disable DTP?
Disable protocol negotiation, hard-code 802.1q protocol at the interface level.
Define and Configure DTP
(config-if)switchport
Dynamic Trunking Protocol. Automatically choose port for Access or Trunk Mode.
What order does DTP try to form?
- Trunk ISL
- Trunk 802.1q
- Access
How do you disable DTP?
switchport no negotiate
or
what is errdisable dtp-flap?
change in trunk encap
What does DTP do?
automatically negotiates a common trunk mode between switches
How do you disable DTP when you configure both ends of the ISL manually?
switchport nonegotiate
What are the 3 trunk encap modes?
isl, dot1q, negotiate (default
What is DTP?
Dynamic Trunking Protocol - A Cisco-proprietary protocol used for negotiating trunking states. used to dynamically negotiate whether the devices on an Ethernet segment want to form a trunk and, if so, which type (ISL or 802.1Q).
What are the 5 DTP modes?
-Access, member of a single VLAN.-Trunk, port attempts to negotiate trunking.-Non-negotiate, port set to trunk but does NOT negotiate.-Dynamic Desirable, Actively negotiates a trunk, and links if other side is Trunk, DD, or DA.-Dynamic Auto. Passively waits for other side to negotiate trunk. Links if other side is trunk or DD.
How often are DTP frames sent out on switchports?
Every 30 Seconds.
What does *DTP* stand for?
Dynamic Trunking Protocol
What are the modes of DTP?
DTP has two modes, auto and desirable. Auto passively converts to a trunk if the neighbor sends a request. Desirable actively attempts to convert a link to trunk.
What configuration command sets up DTP?
Switch(config-if)# switchport mode <auto></auto>
What configuration command sets up non-DTP trunk?
Switch(config-if)# switchport mode trunk
Switch(config-if)# switchport no negotiate
Switch(config-if)# switchport trunk allowed vlan …
