Connectivity Guide
OS10(conf-if-po-1)# lacp fallback enable
OS10(conf-if-po-1)# lacp fallback timeout 20
OS10(conf-if-po-1)# lacp fallback preemption enable
View LACP fallback conguration
OS10# show port-channel summary
Flags: D - Down I - member up but inactive P - member up and active
U - Up (port-channel) F - Fallback enabled
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Group Port-Channel Type Protocol Member Ports
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1 port-channel1 (UF) Eth DYNAMIC 1/1/10(P) 1/1/11(I)
LACP fallback in non-VLT network
In a non-VLT network, LACP fallback enables rebooting of ToR or server connected to the switch through normal LACP. The other end of
the switch is connected to a DHCP/PXE server, as shown in the following illustration:
In the above scenario, LACP fallback works as follows:
1 The ToR/server boots up.
2 The switch detects the link that is up and checks fallback enabled status. If fallback is enabled, the device waits for the time-out
period for any LACP BPDUs. If there are no LACP BPDUs received within the time period, then the LAG enters into fallback mode and
adds the rst operationally UP port to the port-channel instead of placing it in an inactive state.
3 Now the ToR/server has one port up and active. The active port sends packets to the DHCP/PXE server.
4 After receiving response from the DHCP server, the ToR/server proceeds to boot from the TFTP/NFS server.
5 When the ToR/server is fully loaded with the boot image and congurations, the server starts sending LACP PDUs.
6 When the switch receives LACP PDUs from ToR/server, the device comes out of the fallback mode and activates the LAG through
normal LACP process.
Layer 2
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