Port-channel state is down for unknown reason

[Chu Huy Long]

Hi everyone,

I'm managing an UCS system running firmware version 3.1(2b).

Currently, there are a pair of port-channel displaying state down when checking by CLI or monitored by Solarwind (portchannel 1440 & 1441 in attached images).

CLI logs on FI-A:

# show port-channel summary

....

1440  Po1440(SD)  Eth      NONE      Eth7/1/5(D)  
1441  Po1441(SD)  Eth      NONE      Eth7/1/6(D) 

....

CLI logs on FI-B:

# show port-channel summary

.....

1490  Po1490(SD)  Eth      NONE      Eth7/1/5(D)  
1491  Po1491(SD)  Eth      NONE      Eth7/1/6(D) 

....

Full show log is attached.

There is no blade in slot 7/5 & 7/6.

There is no alert on UCSM & all other port-channels are up.

Can anybody advise us what is the problem here?

Thanks and regards,

Mr Busy

[Walter Dey]

Please do "show interface pc...." to see all the members !

what show show cdp neighbours !

is this a vpc ?

https://supportforums.cisco.com/video/11931936/implementing-vlans-and-port-channel-ucs-system

[Chu Huy Long]

As I know, these are internal port-channel created by UCS.

show interface port-channel ...

already included in log file:

XXXXXX-FI-A(nxos)# show interface port-channel 1440

port-channel1440 is down (No operational members)
  Hardware: Port-Channel, address: 0000.0000.0000 (bia 0000.0000.0000)

....

XXXXXX-FI-A(nxos)# show interface port-channel 14401

port-channel1441 is down (No operational members)
  Hardware: Port-Channel, address: 0000.0000.0000 (bia 0000.0000.0000)

...

XXXXXX-FI-B(nxos)# show interface port-channel 1490

port-channel1490 is down (No operational members)

...

XXXXXX-FI-B(nxos)# show interface port-channel 14901

port-channel1491 is down (No operational members)

....

[Walter Dey]

Did you configure pc between IOM and FI ?

[Chu Huy Long]

Hi Walter Dey,

Yes, we configured port channel between IOM &FI.

IOM: 2204, plugged all 4 ports with twinax cable

FI: 6248

[Chu Huy Long]

Hi all,

Found the reason. Fex ports of those po are mapped to a blade that is not installed OS, so their state should be down (as I understand).

But could you explain what is the meaning of calling these ports "Port-channel"?

--------------------------------------------------------------------------------
Group Port- Type Protocol Member Ports
Channel
--------------------------------------------------------------------------------

...

1400 Po1400(SU) Eth NONE Eth3/1/9(P)
1401 Po1401(SU) Eth NONE Eth3/1/10(P)

...

Is there anyone understanding the naming here?

[Walter Dey]

A very nice explanation can be found in

http://www.tbijlsma.com/2012/03/how-ucs-achieves-80gbe-of-bandwidth-per-blade/

where you see an implied pc of 2 backplane links between 2204 and VIC-1280, resp 4 backplane links between 2208 and VIC-1280. They of course only show up, if a OS is installed.

[Chu Huy Long]

Hi Walter Dey,

Thanks for the reference. I have read it.

Given the fact when using a set of VIC 1340, 1380 + IOM 2204, we have 4 link between blade and IOM pair (2 for each one). And those 4 links are implied as port-channels as shown in logs.

But when reading B200-M4 specsheet, I found another diagram as in attached file, where there are only 2 port channels, each port-channel bundle 1 link from 1340 and 1 link from 1380. So which one is correct?

Thanks

[Walter Dey]

Between each blade, there is one pc to the left resp. right IOM.

The number of links per pc is determined by the IOM model: 2204 : 2 , 2208 : 4

And the VIC1240/1280 resp. 1340/1380 have each 2 traces for left, resp right IOM

[Chu Huy Long]

Right, that's what makes me confused.
How can I show the 2 port-channel in vic_1340_1380_and_iom2204.png? I think there should be only 1 port-channel viewing from each FI.

[Walter Dey]

Hi Chu

Just for clarification: there are pc between blade and IOM (over the traces of the chassis backplane) AND different pc between IOM and FI.

Walter.