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Cisco Bug: CSCuq25337 - Broadcast & multicast fail after multiple ISSU, no port select for LTL

Last Modified

Nov 27, 2020

Products (8)

  • CiscoPro Workgroup EtherSwitch Software
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco Nexus 7700 6-Slot Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco Nexus 7700 10-Slot Switch
  • Cisco Nexus 7000 9-Slot Switch

Known Affected Releases

6.1(2) 6.2(10)S38 6.2(2a) 6.2(6a) 6.2(8) 6.2(8a)

Description (partial)

Symptom:Broadcast / multicast traffic may not egress out port channel members and/or physical ports.
pixm pss has duplicate entries for BD LTLs after multiple ISSU

 slot 4 show hardware intern ltl start-index 0x802b end-index 0x802b egress-port 6
----------------------------------------------------------------
|fp ports|inst| ltl | rbh|   vqi   |mi(v5)|mi(v4)|drop|eg ports|
|--------------------------------------------------------------|
| 5- 8   |   1| 802b|   0|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   1|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   2|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   3|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   4|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   5|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   6|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   7|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   8|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|   9|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|  10|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|  11|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|  12|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|  13|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|  14|         |    c9|    ca|   0|no port selects
| 5- 8   |   1| 802b|  15|         |    c9|    ca|   0|no port selects
Conditions:Multiple ISSUs causing incorrect setting of the port bitmaps due to pss key corruption.
For example, lets take a 2 ISSUs case from 6.2.8 to 6.2.8a to 6.2.10

- Switch loaded with 6.2.8 image. 
- On a BD ltl operation if any, upon updation of the pss entry in the pss file, there is a mismatch between the pixmc internal data structure and the pss entry. 
- After ISSU from 6.2.8 to 6.2.8a, the restoration of BD LTL is done based on the mismatched state. This results in inconsistency between pixmc internal sw state and its pss file only without affected the hardware programming.
- Now, any BD ltl operation on the above affected BD LTL will result in creation of a duplicate key in the pss file.
- Another ISSU from 6.2.8a to 6.2.10 will result in restoration of an invalid PSS entry (because of duplicate pss key) which has stale port bitmaps set for that BD LTL.
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