LAN Routing
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5400 routing through a vlan

Frequent Advisor

5400 routing through a vlan

Hi we are doing ip migration. Our core switch is connected to our ISP and ISP's router is a cisco router.

The cisco router is configuration as encaplation dot1Q.

At our side, we are planning to config multiple vlans.

All of zones have same vlan id.

Our core switch is 5400.


As describe above.

Our question is:

Can we route all of our subnets through a single vlan to ISP?


Honored Contributor

Re: 5400 routing through a vlan

Depends on your setup, but most likely yes.

CCIE Service Provider
MASE Network Infrastructure [2011]

Trusted Contributor

Re: 5400 routing through a vlan

You need to decide where your inter-VLAN routing is going to be performed:

 - on the 5400


 - on the ISP's router.


If you do it on your 5400, then you create a VLAN interface for each VLAN you are using and put the default GW address for each VLAN's subnet on that VLAN interface.

You then create a new VLAN for your connection to your ISP router and add a default route pointing at that link.


If you are going to use your ISP to route between your subnets, then you trunk all VLANs up to the ISp router by adding them to the connecting switchport as tagged VLANs except for any VLAN that your ISP router has as "native" which you put on the link at your end as untagged.