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F5 big ip i5600 lacp query


Hello all,

Ive been trying to setup LACP (for dmz traffic) with both ports in up state on interface 2.1 and 2.2 of an HA pair i5600 bigip in active standby mode with a cisco 3850 switch running version 16.6.5

On the cisco switch i only see P and S (show etherchannel summary) for ports connected to 2.1 and 2.2, do i have to bundle the 2.1 and 2.2 interfaces since i have tried to bundle them and it doesnt work. How do i get a combined bandwidth of 20 Gigs on 2 interfaces on the F5? Right now its only 10 Gig.

Also 2.1 and 2.2 are trunked and allow 1 vlan.

Also im already using 40 Gigs sfps for internal traffic which are in a working port channel and it will be overkill to use more 40Gig transcievers for this dmz traffic. Just want to make the 10 Gig interfaces work for this case.

show etherchannel summary output on cisco:

35 Po21(SU) LACP Te1/0/x(P) Te1/0/y(s)
36 Po22(SU) LACP Te2/0/x(P) Te2/0/y(s)

F5 version is on 16.1.0


Community Manager
Community Manager

@kbk491 - thank you for the very detailed question.
In the interest of time, If you have a support contract, I recommend opening a ticket with them (especially useful for extremely specific/detailed requests like this) while I look around a bit to see if anyone in the community might have any info?


i did open a ticket and they will reach out to me in a couple of hours (hopefully before i leave for the day which is like in 2 hours). So lets see how it goes.

Thanks for the update - I reached out to some folks who *may* know about this sort of thing, or be able to offer advice, but Support is still a very authoritative, best-bet.

That said, the community at large *may* yet have some out-of-band experience that could help...we'll see.


Cisco is the Active LACP by default.  Did you set 5600 to passive? 

They are both active active.

changed the trunk to passive on f5 but no change, stilll combined speed of 10Gigs instead of 20 and port channel status show as P and s on cisco side (same as before).

anyways im waiting for optics to arrive then i will engage support again