Native Vlan other than 1

[nathan.spena]

We are currently using a native vlan other then 1  in our general deployments.

We have been testing the 6509 (sup2-t) running 15.1 (sy7) connecting to a 3850 switch.

We want to know whether its possible to use a native vlan other then 1.  so the downstream switch ( 3850 ) picks this up during the PnP bootup,.

I've been doing packet captures with the team from a new out of box switch, to see what the initial setup traffic looks like, e.g. dhcp requests etc.

So far, consistently, 3 or 4th packet is a dhcp request, to 0.0.0.0, with no vlan id tag in frame.

This leads me to believe if they connected this switch to our upstream switch, and configured the upstream switch port trunk native vlan to be the network management VLAN ID, which has a usable L3 address/svi and can route to our DHCP platform (which has usable pool configured), it should be able to obtain an IP address

the pool is also configured with the required option to direct to APIC EM, which is reachable from this vlan.ie just require the ability to act as a "host" at first, and pass untagged packets to do required DHCP interactions and find APIC EM. I understand long term we might want to use the PNP vlan commands to have the switch configure a management vlan other than vlan1, and therefore match our normal sw mananagement vlan ids, etc.

[Geevarghese Cheria]

Hi Nathan,

  After referring some of the similar C3- cases would like you to try the following..

• Pnp startup vlan on the running configuration

on the upstream switch can you make sure the following command are typed ..
(Not sure about 6k IOS commands)....

#sh run | i pnp
ip dhcp pool pnp
vrf nm
network <ip><subnet>
default-router <ip>
option 43 ascii <>
lease 0 0 5
pnp profile <name>
transport http ipv4 <ip> port 80
pnp startup-vlan <no>

then try the below command on both the switches

sh cdp tlv app

Also request to take the logs for that

Generate a log bundle by opening an SSH session to APIC-EM as username grapevine, then issuing the command rca.

Thanks and Regards,

Geevarghese

[Geevarghese Cheria]

Hi

  also check if the following commands are also typed...

on the 6500-Sup2T side

interface Port-channel<>

switchport

switchport trunk native vlan <no>

switchport trunk allowed vlan <allowed range with 3850>

switchport mode trunk

Thanks and Regards,

Geevarghese

[aradford]

Hi Nathan,

pnp startup-vlan xxx command is the recommended way to solve this problem.

My blog posts have details on how this works.

Network Automation with Plug and Play (PnP) – Part 4

I also show an ether channel example in this blog too Network Automation with Plug and Play (PnP) – Part 5

You would need to check that your 6k software supports "pnp startup-vlan xx"

You need to take management vlan, native vlan, ether channel, trunks into consideration.

There is also a way to do this without "pnp startup vlan", but you need to create the management vlan on the switch (and depending on the switch, you will need an EEM script to do this).

Also, there are some issues with older versions of 3850 code and NV1 (see PnP release notes for details).  What version of 3850 code are you running?

Adam