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Cisco Bug: CSCvu87859 - OSPF LSAs are not refreshed after failed ISSU

Last Modified

Oct 22, 2020

Products (2)

  • Cisco Nexus 9000 Series Switches
  • Cisco Nexus 9000 Series Switches

Known Affected Releases

7.0(3)I7(8) 9.3(1) 9.3(4) 9.3(5)

Description (partial)

Symptom:
OSPF LSAs are not refreshed by a Nexus 9000 device after a failed attempt to update the NX-OS software of the device via ISSU. As a result, OSPF neighbors will eventually age out these LSAs, removing OSPF routes with the Nexus 9000 device as a next-hop IP address from the routing table.

For example, consider a Nexus 9000 device named "N9K-1" that failed an update via ISSU.

N9K-1# show logging logfile | include ignore-case issu
<snip>
2020 Jul  2 14:55:01.869 N9K-1 %USER-0-SYSTEM_MSG: ISSU Error: Service "vpc" has blocked the upgrade  - sysmgr
2020 Jul  2 14:55:01.102 N9K-1 %SYSMGR-3-ISSU_BEGIN_FAILED: ISSU cannot proceed (error-id 0x401E0067).

Some time (typically less than an hour) later, connectivity to prefixes advertised by N9K-1 via OSPF may be disrupted, as OSPF neighbors flush the LSAs advertised by N9K-1 from their local Link State Database. An example of this is shown below, where N9K-1 has an OSPF Router ID of 192.0.2.10 and N9K-Spine has an OSPF Router ID of 192.0.2.20.

N9K-1# show ip ospf | include ID
 Routing Process 65535 with ID 192.0.2.10 VRF default

N9K-Spine# show ip ospf | include ID
 Routing Process 65535 with ID 192.0.2.20 VRF default

N9K-1# show ip ospf database 
        OSPF Router with ID (192.0.2.10) (Process ID 65535 VRF default)

                Router Link States (Area 0.0.0.0)

Link ID         ADV Router      Age        Seq#       Checksum Link Count
192.0.2.10     192.0.2.10      439        0x80000d1b 0x9d22   7   
192.0.2.20    192.0.2.20      32163       0x80000a76 0xfbb9   7   

N9K-Spine# show ip ospf database 
        OSPF Router with ID (192.0.2.20) (Process ID 65535 VRF default)

                Router Link States (Area 0.0.0.0)

Link ID         ADV Router      Age        Seq#       Checksum Link Count
192.0.2.20    192.0.2.20      32163       0x80000a76 0xfbb9   7   

N9K-1# show ip ospf neighbors 
 OSPF Process ID 65535 VRF default
 Total number of neighbors: 1
 Neighbor ID     Pri State            Up Time  Address         Interface
 192.0.2.20         1 FULL/ -          1d00h    192.0.2.20    Eth1/1 

N9K-Spine# show ip ospf neighbors 
 OSPF Process ID 65535 VRF default
 Total number of neighbors: 1
 Neighbor ID     Pri State            Up Time  Address         Interface
 192.0.2.10        1 FULL/ -          1d01h    192.0.2.10      Eth1/1

Conditions:
1. OSPF adjacency between one or more remote routers and a Nexus 9000 device.
2. Recent ISSU failure on the Nexus 9000 device.
3. OSPF LSAs are not refreshed by Nexus 9000 device some time after the ISSU failure on the Nexus 9000 device.
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