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This defect describes behavior when creating mixed-speed port groups. Mixed-speed port groups are unsupported on this switch for all versions, but it is handled differently by release. Consider three ranges of NX-OS releases. 1. Range one includes those before the first patch [X.X - 9.3(8)]. 2. Range two includes those between the two patches [9.3(9) - 9.3(X)]. 3. Range three includes those after the second patch [10.1(1) - X.X]. A description of expected behavior when attempting to bring up a mixed-speed port group for all three ranges follows: RANGE ONE [X.X - 9.3(8)] Only ports operating at one speed will remain up within the port group. The speed which continues to work is not defined. All other speeds will go down with the reason "Link not connected". Additionally, ports outside the port group (but within the slice) can experience issues related to MAC credit exhaustion. This can cause control plane protocols which use MAC credits (such as CDP, UDLD, and BFD) to stop functioning. RANGE TWO [9.3(9) - 9.3(X)] Only ports operating at one speed will remain up within the port group. The speed which continues to work is not defined. All other speeds will go down with the reason "Link not connected". MAC credit exhaustion issues are not expected in this range. RANGE THREE [10.1(1) - X.X] Only ports operating at one speed will remain up within the port group. The speed which continues to work is the one which is brought up first. Trying to bring up any other speed after will cause the new speed to go down with the reason "XCVR speed mismatch". MAC credit exhaustion issues are also not expected in this range.
This problem affects N9K-C9364C-GX and N9K-C93600CD-GX switches with mixed-speed port groups. Mixed-speed port groups are created when you try to bring up ports with at least two different speeds inside the same group. Port groups 7 and 8 are not affected for N9K-C93600CD-GX devices. Port groups are defined as follows: N9K-C9364C-GX: 1 - e1/1-4 2 - e1/5-8 ... 16 - e1/61-64 N9K-C93600CD-GX: 1 - e1/1-4 2 - e1/5-8 ... 6 - e1/21-24 7 - e1/25-26 8 - e1/27-28 As mentioned in the Symptoms portion, 9.3(8) and earlier versions can also experience control-plane issues across the slice. Slices are defined as follows: N9K-C9364C-GX: 0 - e1/1-24, e1/51-53 1 - e1/25-50, e1/54 N9K-C93600CD-GX: 0 - e1/1-4, e1/34-36 1 - e1/5-20 2 - e1/21-29
It is unsupported to bring up mixed-speed port groups on all NX-OS versions. There is no workaround for this. You must remove all but one speed from the port group. In some cases, you may also need to shut and no shut the remaining interfaces to recover after creating a mixed-speed port group. The related control plane issues, which are only known to affect 9.3(8) and earlier, can only be mitigated by reloading the switch.
MAC credit exhaustion is a condition which can be verified with the following command: 'slot 1 quoted "show hardware internal tah mac-credit-info"'. A device which is not experiencing MAC credit exhaustion will return a blank table: Unit: 0 Slice: 0 ================================================================== FP-Port | srcid | mac | mac_subport | mac_credits | flow_control | ================================================================== Unit: 0 Slice: 1 ================================================================== FP-Port | srcid | mac | mac_subport | mac_credits | flow_control | ================================================================== Unit: 0 Slice: 2 ================================================================== FP-Port | srcid | mac | mac_subport | mac_credits | flow_control | ================================================================== Unit: 0 Slice: 3 ================================================================== FP-Port | srcid | mac | mac_subport | mac_credits | flow_control | ================================================================== This is an example output from a switch experiencing MAC credit exhaustion: Unit: 0 Slice: 0 ================================================================== FP-Port | srcid | mac | mac_subport | mac_credits | flow_control | ================================================================== 49/1 | 120 | 15 | 0 | 0 | 1
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