Trunk and Access VLAN

[ney25]

Hi NetPro,

something new to me, wish netpro can share to me and guide me how to resolve this.

Upstream Switch A- model WS-C3750G-12S-S (version 12.2(35)SE5)

Downstream Switch B - Model WS-C3560-24PS-S ( version 12.2(35)SE5)

vtp domain - jack

vtp mode - transparent.

vtp version - 2

when i configured both switch as trunk and dot1Q. it doesn't work.

so, i tried to change it to access vlan. and it work successful.

i am curious. what wrong with this ?

regards,

jack

[andrew.prince]

Then I am confused - what is the issue, if you have change the IP address, and the connection between the 2 switches is a trunk, then trunking is working.

[ney25]

hahaha, yeah that's my concern.

i also don't know what to do now, i am pretty blur . this is my first time encountered this problem.

like i mentioned to you earlier. another site which having the same config (the only different is the switch they are using 3560 ) and it was working.

now then my upstream switch is 3750 but doesnt work.

[andrew.prince]

OK listen - The trunking in your sim is working. Further testing will prove this:-

1) Create more vlans on both switches, and give them IP addresses and ping between them.

2) Configure VTP on the switches - as the name suggests VLAN Trunking Protocol WILL NOT work if there is NO trunk between 2 switches.

3) If you have some switches in a production environment that are not trunking 100% CHECK THE CONFIG.

Trunking is one of the most basic, turn it on and it will work protocols in the Cisco Switch environment, if it's not working, there is a config issue or physical issue 99.99% of the time.

HTH>

[ney25]

Ok, will try again and get back to you.

thanks bro.

have a nice day.

[andrew.prince]

np.

[Leo Laohoo]

Just to add: Make sure "IP Routing" on the 3750 is disabled (no ip routing).

[ney25]

Hi Leolaohoo.

yes, it was disabled.

any other idea ?

thanks.

[Leo Laohoo]

Can you try to post the "sh run" of the two switches?