dynamic auto and other end trunk

Hi all,
what will happen if one end of the router is set to dynamic auto and other end router is set to trunk? Will they trunk or not?

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Comments

bbarrick

Pretty sure they trunk.

https://learningnetwork.cisco.com/message/22582#22582

DCD

You mean switches, yes they will trunk.

bbarrick

DCD wrote: »

You mean switches, yes they will trunk.

lol, One of my goals before taking the test is to pay attention to the words. I'm a fast reader and tend to glance at them without catching what they are. I think this will be harder for me than learning this stuff.

p1xels

Oh I got confused,does routers do trunking?

iamme4eva

Routers do trunking for inter-VLAN routing (router on a stick). But they don't do DTP, so there is no "dynamic auto".

p1xels

Hi eva,
I think it should be VTP and not DTP. Don't remember reading about DTP till now. :-p
BTW,if there is anything called DTP what is the diff between the 2?

Also,I dont think Trunk + Auto = Trunk.

iamme4eva

VLAN Trunking Protocol is the method of Cisco switches telling each other about VLANs, where as Dynamic Trunking Protocol (DTP) is the method of Cisco switches dynamically negotiating a trunk port.

If I remember rightly, the CCNA doesn't actually talk about the specifics of DTP, but the 5 port modes (access, trunk, dynamic auto, dynamic desirable and nonegotiate) are actually part of DTP.

pamccabe

Yes, a link set to dynamic auto and the other end set to trunk WILL, in fact, trunk. All dynamic auto means is that end of the link will not initiate the trunking process. It just sits and waits until the other end asks it if it wants to trunk. When the other end tries to negotiate trunking, it automatically accepts. So if the other end is set to trunk, it will indeed trunk. It will also trunk if the other end were set to dynamic desirable. When dynamic desirable is the mode on one end of the link, that means the link 'desires' to be a trunk so it will initiate the process. Hope that makes sense.

Zartanasaurus

Take two switches, connect them and see what happens when you configure it!