03-05-2009 10:12 AM - edited 03-06-2019 04:24 AM
We are building a VMWare based lab with a layer 3 IOS switch (3750) to do inter-vlan routing from the various vlans within the VM chassis. There will be no switch ports specifically assigned to the VLANS, only trunked interfaces into the VM Chassis. The VLANS are not coming up and subsequently we can't do inter-vlan routing via the L3 switch. Any way to fake out the switch?
03-05-2009 10:16 AM
Hello Michael,
a trunk port should be enough for making the switch happy about autostate
verify the list of permitted vlans on your trunk port to vmware you may need to update it.
also when you create a new SVI you need to do no sh
Hope to help
Giuseppe
03-05-2009 10:41 AM
I neglected to issue any 'vlan' config command (such as name). Named the vlans and everything took off.
Thank you for the affirmation.
03-05-2009 12:15 PM
Glad you fixed it.
Just to make sure you understand, its not the "name" command statement that made it come up, but the creation of the vlan itself in layer 2.
Without the command "vlan 10," for example, vlan 10 will not be created on the switch and will also not carry traffic across any trunk port, even if the trunk port is configured correctly. To the switch, the vlan doesnt even exist....
HTH
03-05-2009 01:57 PM
Hello Michael,
as Victor noted to have an STP instance running the L2 Vlan entity must exist on the switch
After the L2 Vlan broadcast domain is created, STP instance is created and starts to run.
The trunk becomes an STP forwarding port for the vlan.
And the SVI comes up.
For this reason an SVI is a semi-logical interface that is in the middle between physical L3 interfaces and loopbacks
Hope to help
Giuseppe
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