Roy,
Anytime! Happy to help. I'll try my best to concisely explain the LACP rate fast dilemma here.
For instance, you may have a server that requires LACP rate fast, in which case you wouldn't need it configured on the actual NX-OS device since we honor the request from the server (or any given attached device.) Conversely, if you wanted the Nexus to force an attached device to run with LACP rate fast, you would then configure that on the NX-OS device itself.
When a server (or attached device) requires NX-OS to use rate fast (or when the Nexus requires it), ISSU is not possible because the timeout is far too short to allow the control-plane to behave as expected during an ISSU operation.
You can verify the timers that an interface is using by entering the following CLI:
Example from my box:
RTP-AGG1# show lacp interface ethernet4/8
Interface Ethernet4/8 is up
Channel group is 20 port channel is Po20
PDUs sent: 134665
PDUs rcvd: 4501
<snip>
Local Port: Eth4/8 MAC Address= 0-23-4-ee-c1-e8
System Identifier=0x7f9b, Port Identifier=0x8000,0x408
Operational key=32788
LACP_Activity=active
LACP_Timeout=Long Timeout (30s) << I am configured as "normal"
Synchronization=IN_SYNC
Collecting=true
Distributing=true
Partner information refresh timeout=Short Timeout (3s)
Actor Admin State=61
Actor Oper State=61
Neighbor: 0x308
MAC Address= 84-78-ac-b-60-43
System Identifier=0x8000, Port Identifier=0x8000,0x308
Operational key=19
LACP_Activity=active
LACP_Timeout=short Timeout (1s) << Attached device is requesting "lacp rate fast"
Synchronization=IN_SYNC
Collecting=true
Distributing=true
Partner Admin State=63
Partner Oper State=63
Aggregate or Individual(True=1)= 1
In the above state, although I am configured as "normal" locally, I cannot ISSU:
RTP-AGG1# show lacp issu-impact
For ISSU to Proceed, Check the following:
1. All port-channel member port should be in a steady state.
2. LACP rate fast should not be enabled on member ports.
The following ports are not ISSU ready
Eth4/8 ,
In short, if you are not seeing any LACP rate fast configuration locally, you must have devices attached that are forcing NX-OS to operate at the fast rate and thus makes the chassis ineligible for ISSU. You can either shut these ports while the ISSU completes or toggle the configuration to normal on the attached devices (assuming not strictly required.).
Let me know if you have any other questions!
- Andrea, CCIE #56739 R&S
