Hi,
I tried to upgrade a pair of NEXUS 5596 according to the instructions of "Upgrading from Cisco NX-OS Release 5.1(3)N2(1c) and Earlier Releases (Disruptive Upgrade)" in "Cisco Nexus 5500 Series NX-OS Software Upgrade and Downgrade Guide, Release 7.0(8)N1(1)".
(I can not use ISSU process because of Unsupported Topologies.)
However, when I tried to upgrade the first one, I had a problem which some active ports on near line switches(Catalyst3750x) became err-disable with "stp miss config".
Of course, I expected that some packets would be lost, even though under the vPC, while some active paths were settled to the secondary paths, but not expected port down.
After investigation, I found that the NEXUS started with the default configuration at first and it might issue wrong "bpdu" packets.
(Just after seconds, the NEXUS was running with correct configuration, so I could not find the cause of the problem soon.)
Can I avoid this problem with disconnecting cables to near line switches and finish the upgrade process?
or
Should I make two step upgrade even though it is "Disruptive Upgrade"?
(Does everyone not recommend to make direct upgrade as Release 5.1(3)N2(1c) was not on the list of upgrade path for Release 7.0(8)N1(1) even though the document mentioned above is posted on the Support Web site?)
Please get me your advice.
