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Community Member

switch-to-switch

How do I configure a Catalyst port switch to connect to another Catalyst port (uplink connection) and allow some VLANs to pass through that uplink ?

11 REPLIES
VIP Purple

Re: switch-to-switch

Basically, you need to configure a trunk between these 2 ports. What type of switches?

Brandon

Community Member

Re: switch-to-switch

I would like to connect one of the Catalyst 2980G's port to the port on Catalyst 3750 (uplink).

Are there things that should be taken care of when configuring trunk since the 3750 switch is on production ?

Re: switch-to-switch

Hi Joseph,

Here is how you configure trunking

interface FastEthernet0/1

description Connection to SW1

power inline never

switchport trunk encapsulation dot1q

switchport trunk native vlan 999

switchport trunk allowed vlan 20,25,999

switchport mode trunk

speed 100

duplex full

power inline never - disabled POE on the port

switchport trunk encapsulation dot1q - sets the encapsulation to 802.1q

switchport trunk allowed vlan 20,25,999 - is the vlans allowed to trunk over this port

switchport mode trunk - sets the port to trunking mode.

speed 100 - sets the speed to 100mb, depending on your connection

duplex full - sets the connection to full duplex using a crossover cable.

switchport trunk native vlan 999 - this is a security feature to change the native vlan 1 to native vlan 999 for security reasons. This can be any vlan numbber. This is optional

Hope this helps, please rate.

Cheers,

Justin

Community Member

Re: switch-to-switch

Do I configure the same parameters for both switches ?

Re: switch-to-switch

Hi Joseph,

You have to match the encapsulation, speed, duplex.

Regards,

Justin

Re: switch-to-switch

Hi Joseph,

You have to match the encapsulation, speed, duplex. You probably want to match everything as a good rule of thumb that you can.

Regards,

Justin

Community Member

Re: switch-to-switch

By the way, am I not going to disrupt the service if I do the following configurations ? Or do I need to check on something in the switches ?

Community Member

Re: switch-to-switch

By the way, what if the port that I am connecting my new switch is a member of vlan 10 and I want that all ports of my new switch be a member of vlan 10 also ?

Community Member

Re: switch-to-switch

My concern here is, I have switch A with 24 ports. The 4th port is currently configured to be a member of VLAN 10. Thus, switchport access vlan 10 on its interface configuration.

I wanted to connect another 24 port switch in my network and would want it to connect to Switch A's 4th port because users on the additional switch will also be configured as members of VLAN 10.

How do I go about this ?

Thanks.

Re: switch-to-switch

Hi Joseph,

As far as I understand, the 4th port of SwitchA is configured as an access port in vlan10. You must have the "switchport mode access" command also configured.

You can connect SwitchB to the 4th port of SwitchA.

The respective port on SwitchB can be an access port as well, and all the traffic from SwitchB will be carried over to SwitchA, but it will be a vlan10 traffic within SwitchA.

This may be a working config, if you do not plan to have more than 1 vlan on SwitchB, or to implement QoS on the network.

As soon as you have more than 1 vlan on Switch B and Switch A, you will need to configure a trunk between the switches.

Also, for QoS, it is necessary to implement trunks, as the CoS priority field is carried within the trunk encapsulation.

Cheers:

Istvan

Community Member

Re: switch-to-switch

thank you for your reply. i will try that.

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