Switches defaults to dynamic auto or desirable?

feng.lian

For trunking that is. The Odom book says auto while CBT Nuggets says desirable.

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Comments

peanutnoggin

All switches that I've seen are default set to dynamic desirable. HTH.

-Peanut

pitviper

both

c3560_SW1#sh int f0/10 trunk

Port Mode Encapsulation Status Native vlan
Fa0/10 auto negotiate other 1

NME_16ES#sh int f1/0/10 trunk

Port Mode Encapsulation Status Native vlan
Fa1/0/10 auto negotiate other 1

c2950_SW4#sh int f0/10 trunk

Port Mode Encapsulation Status Native vlan
Fa0/10 desirable 802.1q not-trunking 1

Looks like maybe "auto" on newer switches, and "desirable" on older switches.

feng.lian

My, I hope there won't be a direct question on this in the exam. If there is I'll probably choose auto. Thanks for the answers.

JSK

I love CBT Nuggets but in a situation like this I would trust the official exam book.

pitviper

From Cisco.com - IOS 12.2

Catalyst Switches

The default mode is dependent on the platform; it should be either dynamic auto for platforms that are intended as wiring closets or dynamic desirable for platforms that are intended as backbone switches. The default for PVLAN ports is that no mode is set.

alan2308

pitviper wrote: »

From Cisco.com - IOS 12.2

Catalyst Switches

The default mode is dependent on the platform; it should be either dynamic auto for platforms that are intended as wiring closets or dynamic desirable for platforms that are intended as backbone switches. The default for PVLAN ports is that no mode is set.

And last I heard, the CCNA was written for the 2960. So for the CCNA, dynamic auto.

tha_dub

alan2308 wrote: »

And last I heard, the CCNA was written for the 2960. So for the CCNA, dynamic auto.

I'm going with that as well. Just keep in mind 2 switches with dynamic auto will not trunk. One has to be set to dynamic desirable or trunk. I would expect in the exam they will tell you what kind of switch you are looking at for any particular question.

mella060

You will find that most newer switchs, such as 2960 or 3560 will default to dynamic auto. That way they wont accidently form a trunk with a neighbouring switch. Its just a security measure really. Obviously if you have switches that default to dynamic desirable, then they will actively try to negociate trunk links. Now you as the admin, might not want that to occurr. It just means that when you buy a new switch, you dont have to worry about trunk links accidently forming.

Older switches will default to dynamic desirable.

tha_dub

I quite like the new configuration because it forces people to have some basic knowledge to get even a small Cisco network going.

It reminds me of Soho wireless gear that comes out of the box wireless open to the world!
Who's great idea was that?