Dell N2000 – How to Capture PCAP to NVRAM?

This can be done, see the page 15 of the Dell white paper on the subject here: http://www.dell.com/downloads/global/products/pwcnt/en/pwcnt_stacking_switches.pdf

Specifically it says:

Merging Two Operational Stacks

The recommended procedure for merging two operational stacks is as follows:

1. Always power off all units in one stack before connecting to another stack.
2. Add the units as a group by unplugging one stacking cable in the operational stack and physically connecting all unpowered units.
3. Completely cable the stacking connections, making sure the redundant link is also in place.

Two operational stacks can also be merged by reconnecting stack cables without powering down units in either stack. Connecting a powered up standalone unit to an existing stack leads to same behavior as when merging two operational stacks. In such cases, Manager reelection is done and the Manager with the higher MAC address wins the election. The losing stack manager resets itself and all its member units. After the reset, all the losing stack members join the winning stack to form a single stack. The winning stack remains functional through the merge process. If the stack merge is performed in this way, then it is strongly recommended that the user set the admin management preference of the desired winner stack manager to a higher value than the stack manager that should lose the election.

Also, in your above proposed cabling you are not completing a loop with your stacking cables. You should always aim to do this, even though it is not a requirement. See page 7 of the Dell m6220 stacking use case: http://i.dell.com/sites/content/business/solutions/whitepapers/zh/Documents/powerconnect-m6220-switch_cn.pdf

Cabling:

M6220 switches should be stacked together by connecting a stacking cable from stack port xg2 of one switch to stack port xg1 of the next sw itch. The stacking cable is included with the stacking module. Stack port xg2 of the fi nal switch in the stack should be connected to stack port xg1 of the first switch, completing the stack loop. A loop topology is not strictly required for a stack but it is recommended, as it is the most robust stacking topology and has seen the most time in production use.

The first thing I'd verify is that the phone is actually tagging frames with that VLAN ID, perhaps with a network tap or port mirror (which might not quite work right on this switch)

If you manually had configured the phone to do that and you know it's working, this is probably a bug in the software.

If not, manually set it on the phone or configure LLDP-MED (Link Level Discovery Protocol) on the interface to do this automatically. Depending on the type of phone (this includes most Polycom, Avaya, and Cisco), it should listen for LLDP packets and learn what the voice VLAN tag is and start sending on that tag.

my-dell-switch(config-if-1/g1)#lldp med