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Why do we need speed 1000 command to bring up a Port-channel interface on a VDX 6740T-1G switch?

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TitleWhy do we need speed 1000 command to bring up a Port-channel interface on a VDX 6740T-1G switch?
Question
There have been some concerns recently regarding the requirement speed 1000 command when setting up a port-channel interface on a VDX 6740T-1G switch. Perfeedback from users, since VDX 6740T-1G is by default a 1G switch, the port-channel interface should have a default speed of 1G. There should notbe a need to definethe speed 1000 command, explicitly when the underlying physical interfacesdefault to1G speeds.

On a 6740T-1G switch, the interfaces are 1G by default. When bringing up individualinterfaces, auto negotiation works fine, and the speedsare negotiated at 1gig.
Once the port channel is configured, the ports stay admin down until the
speed 1000 command is added in the port channel CLI:

Interface port-channel 2500
Vlag ignore-split
Switchport
Switchport mode trunk
Switchport trunk allowed vlan add 605,3305
Switchport trunk tag native-vlan
Switchport trunk native-vlan 605
Spanning-tree shutdown

Interface TenGigabitEthernet 211/0/11
Channel-group 2500 mode active type standard
Lacp timeout short
No shutdown

Interface TenGigabitEthernet 213/0/11
Channel-group 2500 mode active type standard
Lacp timeout short
No shutdown

If speed 1000 isabsent underPO config, the physical interfaces remain admin down due to speed mismatch:

TenGigabitEthernet 1/0/1 unassigned default-vrf administratively down down (Port & Agg speed mismatch)
TenGigabitEthernet 1/0/2 unassigned default-vrf administratively down down (Port & Agg speed mismatch)

Environment
Answer
The speed 1000command is generic across all the platforms.
As port-channel is a global config, this commandhas been madeunique under PO mode to handle different platforms participating in a vLAG.

For example:

For vLAGs, one RB can be 6740T-1G and another RB can be callisto-60, so the member ports can be 1G & 10G.

Additional notes

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