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Port usage of Cisco Blade Switch 3120G

Trusted Contributor

Port usage of Cisco Blade Switch 3120G

Yoji had some port questions regarding the Cisco 3120G blade switch :




This is a question about Cisco Blade Switch 3120G (451438-B21).


Could you let me confirm that the 2 of 4 RJ-45 ports are exclusively used with stacking ports, not with internal crossover connection ports ?

In other words, the stacking ports and cross-connect ports are exclusive, aren't it ?


Quick Specs of the switch says;


4 external 10/100/1000BASE-T RJ-45 ports. Two of these ports can be configured to provide an internal crossover connection to an associated additional Cisco Catalyst Blade Switch 3120 =====


But when a customer enabled the cross-connect ports (17 & 18), all of 4 RJ-45 ports were still usable (linked-up).


The Getting Started Guide indicates that stacking the switch will disable the cross-connect ports, and not mention to any restriction about the RJ-45 ports (ports 23 to 26).

The customer is not stacking.


So I'm assuming all of 4 RJ-45 ports are always usable regardless of the internal cross-connect ports are enabled or not. Correct ?




Input from Steve:




If you use stacking on the 3120, you are using 2 stackwise ports that are independent of any of the uplink or cross connect ports. When using stacking, Cisco does not allow and disables the internal cross connect ports.

The RJ45 and XFP uplink ports are not affected and are totally separate and independent from the stacking ports or cross connect ports.




Other questions?