05-10-2019 09:52 AM
I have a 5400 switch (using as a core switch) with VLANs configured - housing the SVI (default gateway) for the whole site.
Then I have 2 further 5400 switches which are linked to the core switch using Trk interfaces (aggregated interfaces) ... these access switches just have the VLANs configured but no ip addresses.
Am I right in thinking I just tag the VLANs with these Trk interfaces on the access switches? Then tag those VLANs on the core switch back to the access switches?
Nice and simple layer 2 design but will this work with these switches?
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Re: 3 x 5400 trunking at layer 2
05-10-2019 10:57 AM
So just to clarify - if I have 50 VLANs on the core (each one with a IP address configured) ... tag these to both access switches and then on the access switches have 50 VLANs (no IP address configured) and just take the interfaces going back to core it will form a stretched vlan in effect?
Then when someone joins that vlan on an access switch and they need dhcp ... it will trunk them to the core and use a IP helper to get this?
05-10-2019 11:31 AM
This is correct. Tagging multiple VLANs across a single link extends those VLANs to the connected device (keeping in mind that the VLANs do have to be explicitly tagged on both ends of the link), where they will behave as you described. The IP helper/DHCP relay address only needs to live on a device performing IP routing between subnets.