DELL Force10 I/O Aggregator 40Gb Port Question

Today I have received question how to inter connect DELL Force10 IOA 40Gb uplink with DELL Force10 S4810 top of rack switches.

I assume the reader is familiar with DELL Force10 datacenter networking portfolio.

Even if you have 40Gb<->40Gb twinax cable with QSFPs between IOA and Force10 S4810 switch it is in IOA side configured by default as 4x10Gb links grouped  in Port-Channel 128.

If you connect it directly into 40Gb port in Force10 S4810 switch the 40Gb port is by default configured as 1x40Gb interface.

That’s the reason why it doesn’t work out-of-the-box. Port speeds are simply mismatched.

To make it correct you have to change 40Gb switch port to 4x10Gb port. Here is the S4810 command to change switch port from 1x40Gb to 4x10Gb:

stack-unit 0 port 48 portmode quad

Here is the snip from S4810 configuration where 40Gb port 0/48 is configure as 4x10Gb port in port-channel 128

interface TenGigabitEthernet 0/48
no ip address
!
port-channel-protocol LACP
  port-channel 128 mode active
no shutdown
!
interface TenGigabitEthernet 0/49
no ip address
!
port-channel-protocol LACP
  port-channel 128 mode active
no shutdown
!
interface TenGigabitEthernet 0/50
no ip address
!
port-channel-protocol LACP
  port-channel 128 mode active
no shutdown
!
interface TenGigabitEthernet 0/51
no ip address
!
port-channel-protocol LACP
  port-channel 128 mode active
no shutdown

interface Port-channel 128
no ip address
portmode hybrid
switchport
no shutdown