In a Cisco CatOS switch, what is the recommended practice when configuring switch-to-switch intercommunications to carry multiple VLANs for Dynamic Trunk Protocol?
A.
auto to auto_negotiate
B.
disable Dynamic Trunk Protocol when operating in the distribution layer
C.
auto to auto_no_negotiate
D.
desirable to desirable_no_negotiate
E.
on to on_negotiate
F.
desirable to desirable_negotiate
Explanation:
Access Layer Best Practices
When designing the building access layer, you must consider the number of users or ports required to size up the LAN switch. Connectivity speed for each host should also be considered. Hosts might be connected using various technologies such as Fast Ethernet, Gigabit Ethernet, or port channels. The planned VLANs enter into the design.Performance in the access layer is also important. Redundancy and QoS features should be considered. The following are recommended best practices for the building access layer:
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 3
“Set trunks to ON and ON with no-negotiate.”
– P96
Answer F.
Recommendation:
Cisco recommends an explicit trunk configuration of desirable at both ends. In this mode, network operators can trust syslog and command line status messages that a port is up and trunking, unlike on mode, which can make a port appear up even though the neighbor is misconfigured. In addition, desirable mode trunk provides stability in situations where one side of the link cannot become a trunk or drops trunk state.
http://www.cisco.com/en/US/products/hw/switches/ps4324/products_tech_note09186a0080094713.shtml#vlan_trunking_protocol
ok, we are getting conflicting information. According to page 96 of the CCDA cert: Access layer best practices include set trunks to ON and ON with no-negotiate. However the question did mentioned CatOS and according to the documentation listed above from Senior, Cisco recommends an explicit trunk configuration of desirable at both ends. In this mode, network operators can trust syslog and command line status messages that a port is up and trunking, unlike on mode, which can make a port appear up even though the neighbor is misconfigured. In addition, desirable mode trunk provides stability in situations where one side of the link cannot become a trunk or drops trunk state.
Becuase answer E has ON and ON with negotiate, that answer is definitely incorrect and we must assume that answer D is correct per the documentation on CatOS.
A think, correct answer is B.
Because it eliminate needs to spend time to negotiate trunk. (2 sec?)
I agree E. according to this Cisco documentation http://www.cisco.com/en/US/products/hw/switches/ps663/products_configuration_example09186a0080094aec.shtml:
Dynamic Trunking Protocol (DTP)
There are different types of trunking protocols. If a port can become a trunk, it may also have the ability to trunk automatically. In some cases, the port may even be able to negotiate what type of trunking to use on the port. This ability to negotiate the trunking method with the other device has the name Dynamic Trunking Protocol (DTP).
Given the question is about a DTP configuration is sounds like desirable and negotiate must be enabled for DTP to work.
…I mean I agree with F. It is NOT E.
it makes sense, when you turn off negotiation, you can’t really use DTP