configuring L3 in 3750

Answered Question
Nov 7th, 2008
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Hi all,


I would like to configure some L3 interface on 3750 (2 core switches) directly connected to some routers. This routers have to forward the VLANs traffic (production, client, VoIP).

Now I want to know how to configure the interfaces toward the routers out of any VLAN just configured?


I hope someone can help me.


Thank you in advance.


Regards.


Giuseppe.

Correct Answer by Amit Singh about 8 years 6 months ago

Giuseppe,


Could you please eleborate on your requirement. Also paste the running config from the switch.


If you are looking for configuring L3 VLAN interface then simply use:


interface vlan and assign the ip address and related config.



If you have some routers connected to it you can configure the interfaces in two ways :.


1. Configure the interfaces connected to the switch as L3 interfaces and run a routing protocol between the routers and the switch


interface gig x/y

no switchport

ip address


2. You can assign the ports to a respective vlan and have your routers connected to it depending if you have differebt routers for VLANs traffic (production, client, VoIP).


interface gig x/y

switchport mode acess vlan 10


3. If you want the intervlan routing to be done by the routers then you have to configure sub-interfaces and trunk on the router connecting the switch.


-amit singh

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Correct Answer
Amit Singh Fri, 11/07/2008 - 03:05
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  • Cisco Employee,

Giuseppe,


Could you please eleborate on your requirement. Also paste the running config from the switch.


If you are looking for configuring L3 VLAN interface then simply use:


interface vlan and assign the ip address and related config.



If you have some routers connected to it you can configure the interfaces in two ways :.


1. Configure the interfaces connected to the switch as L3 interfaces and run a routing protocol between the routers and the switch


interface gig x/y

no switchport

ip address


2. You can assign the ports to a respective vlan and have your routers connected to it depending if you have differebt routers for VLANs traffic (production, client, VoIP).


interface gig x/y

switchport mode acess vlan 10


3. If you want the intervlan routing to be done by the routers then you have to configure sub-interfaces and trunk on the router connecting the switch.


-amit singh

gpangallo Fri, 11/07/2008 - 09:02
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Hi,


thank you for your answer. I think I would configure the 2nd point in which the switch ports connetted to the different routers have to be a L3 interface (it's a different subnet respect to the other VLANs) without a dynamic routing (static routes). In these interfaces it has to pass all the other VLAN traffic. Some of other ports on the same switch I think I have to configure them as access ports. At the end, I configure the remain ports like the ones configured before for the FW for internet traffic. Because it's necessary to put out the VLAN production, VLAN VoIP, VLAN client traffic.

Is it correct this configuration? Is there an another way to configure them for FW connections?


Please, let me know.


Regards.


Giuseppe

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