Cicso 3120X stacking together link cable question

[chuckk281]

Phunsak had a Cisco 3120X stacking question:

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There are 2x Cisco 3120 installed at interconnect bay #1 and # 2 of c7000 enclosure . In case , I need to stack both together ,,
Is there internal cross connect like we have  in VC Flex-10 module for do that  ?or need  stack cable # 494331-B21 via stacking port?

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We had Lee, Sergey, and Armand jump in with help:

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Lee:  Cisco opted to not use the internal cross connect or the internal serial connections on the C7000. You’ll need to use the external cables.

Then Sergey: It's true for Cisco 3020. Cisco 3120 do have internal cross links. It’s ports 17 and 18.

Next was Armand: You have two options :

-       Using internal crosslink, and then, port 17 and 18 can (or cannot) be used.

-       Using external stack cable, and then, port 17-18 are disabled. This solution enable VSS : both physical switches are seen as one single switch.

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It seems we are good to stack Cisco 3120X switches in a C7000. Are you using this method? Let us know best practices.

[chuckk281]

I also got some information from Steve regarding the difference in using the internal stacking links or the external stacking cable:

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Just for Clarification.

If the Cisco 3120X units are to be “stacked” to look like a single switch, then the included stacking cable must be used and connected between the stacking ports.  This will disable the two internal cross-connects as all interswitch communication will be via the stack connections.

If the customer just wants switch redundancy, then the internal cross connects (either 17, 18, or both) should be used, but do not use the stack cable.

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Hope this helps.