Auto-trunking New Links or Converting a Linear Stack to a Ring with Stack Interactive-setup

Note: The stack interactive-setup utility cannot detect mismatched live stack-trunks. For example, if one end of the trunk is stack-trunk 1/2/1 to 1/2/3 and the other end is stack-trunk 2/2/1 to 2/2/2, stack interactive-setup cannot detect the link 1/2/3 to 2/2/3 and enlarge the stack-trunk 2/2/1 to 2/2/2. The reason is that on one end, port 1/2/3 is an internal port, and on the other end, port 2/2/3 is a data port. The two ports cannot communicate. Output for the show stack command displays mismatch warning messages. Use the multi-stack-trunk command to correct the mismatch problem manually.
Note: Neither stack interactive-setup nor stack zero-touch provisioning can convert a live two-unit stack to a linear-topology trunk. If you are working with a live system, you can enter the multi-stack-trunk ethernet 1/2/1 to 1/2/4 and ethernet 2/2/1 to 2/2/4 command to change the configuration on both units simultaneously. Refer to Changing a live two-unit stack to a linear-topology trunk for more information.

The following example uses stack interactive-setup to add links and convert a four-unit linear stack to a ring. 

ICX7850-48FS Router# show stack
T=2h10m48.9: alone: standalone, D: dynamic cfg, S: static
ID   Type          Role    Mac Address    Pri State   Comment
1  S ICX7850-48FS  active  d4c1.9e18.83e1 128 local   Ready
2  S ICX7850-48F   standby d4c1.9e17.7daf   0 remote  Ready
3  S ICX7850-48F   member  d4c1.9e17.8907   0 remote  Ready
4  S ICX7850-48F   member  d4c1.9e17.7e07   0 remote  Ready

                 standby      active
     +---+        +---+        +---+        +---+
     | 3 |2/1--2/1| 2 |2/5--2/1| 1 |2/5--2/5| 4 |
     +---+        +---+        +---+        +---+
Standby u2 - protocols ready, can failover
Role history: N: standalone, A: active, S: standby, M: member
U1: N->A

Current stack management MAC is d4c1.9e18.83e1

When the stack interactive-setup command is entered, option 2 is selected to probe for new units. Probes are sent out through the ports indicated on the three stack members. 

ICX7850-48FS Router# stack interactive-setup
You can abort stack interactive-setup at any stage by <ctrl-c>
0: quit
1: change stack unit IDs
2: discover and convert new units (no startup-config flash) to members
3: discover and convert existing/new standalone units to members
2&3 can also find new links and auto-trunk or convert chain(s) to ring.
Please type your selection: 2
Probing topology to find clean units...
T=2h11m6.7: Sending probes to ports: u1: 1/2/2 to 1/2/4 1/2/8, u2: 2/2/4 2/2/6 to 2/2/8, u3: 3/2/5 3/2/8, u4: 4/2/1,
Probing in progress ...
Probing in progress ...

Although no new units are discovered, four additional links are detected between the existing stack units. The new connections between units 1 and 2 enlarge the stacking trunk to four ports.

The existing stack does not show a connection between units 3 and 4; however, the stack interactive-setup probes have discovered one shared stacking link, which is expanded to a stack-port on each side to form a ring. 

Existing stack: ============================================================
                 standby      active
     +---+        +---+        +---+        +---+
     | 3 |2/1--2/1| 2 |2/5--2/1| 1 |2/5--2/5| 4 |
     +---+        +---+        +---+        +---+

stack interactive-setup detects 4 new links (classified to 2 logical links) between existing units.
Logical Link #0: U1--U2: 3 link(s): 1/2/2--2/2/6 1/2/3--2/2/7 1/2/4--2/2/8 <-- new links discovered
It will enlarge (stack-port ethernet 1/2/1) to (stack-trunk ethernet 1/2/1 to 1/2/4) and enlarge (stack-port ethernet 2/2/5) to (stack-trunk ethernet 2/2/5 to 2/2/8)

Logical Link #1: U3--U4: 1 link(s): 3/2/5--4/2/1
It will add (stack-port ethernet 3/2/5) and add (stack-port ethernet 4/2/1)
The topology will become a ring.

If you enter y to accept the new configuration, the expanded stack-trunks are formed, and the new stack-ports between units 3 and 4 form a ring. 

Do you accept above new link(s)? (enter 'y' or 'n'): y
T=2h11m27.3: Please wait for background job to finish.
T=2h11m28.4: stack interactive-setup configures stack-port ethernet 3/2/5.
stack interactive-setup configures stack-port ethernet 4/2/1.

Configuration changed. Please do "write memory".

stack-trunk ethernet 2/2/5 to 2/2/8 replaces stack-port ethernet 2/2/5
stack-trunk ethernet 1/2/1 to 1/2/4 replaces stack-port ethernet 1/2/1
ICX7850-48FS Router#
ICX7850-48FS Router# show stack
T=2h11m38.2: alone: standalone, D: dynamic cfg, S: static
ID   Type          Role    Mac Address    Pri State   Comment
1  S ICX7850-48FS  active  d4c1.9e18.83e1 128 local   Ready
2  S ICX7850-48F   standby d4c1.9e17.7daf   0 remote  Ready
3  S ICX7850-48F   member  d4c1.9e17.8907   0 remote  Ready
4  S ICX7850-48F   member  d4c1.9e17.7e07   0 remote  Ready

    active       standby
     +---+        +---+        +---+        +---+
 -2/5| 1 |2/1==2/5| 2 |2/1--2/1| 3 |2/5--2/1| 4 |2/5-  <-- Units 3 and 4 connect
 |   +---+        +---+        +---+        +---+   |      to form a ring.
 |                                                  |
 |--------------------------------------------------|
Will assign standby in 78 sec due to election

Standby u2 - wait for standby assignment due to election
Role history: N: standalone, A: active, S: standby, M: member
U1: N->A

Current stack management MAC is d4c1.9e18.83e1
ICX7850-48FS Router#

After you have confirmed the configuration, be sure to save the configuration with the write memory command. 

ICX7850-48FS Router# write memory
Parent topic: Scenario 1 - Using Stack Interactive-setup to Create a Stack