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Virtual Connect: LACP Timer

Trusted Contributor

Virtual Connect: LACP Timer

Tobias had a customer question on LACP:






A customer has asked if the LACP Timers can be customized for Virtual Connect?





Lot of input on this question:




Mark replied: 



FYI we had an issue, recently, between VC and Cisco Nexus, about LACP timing issue. VC use a short, non configurable, timing: 3sec

Cisco Nexus, used a fixed long timing: 10sec. That created loss of connectivity.

Cisco released a new NX-OS version which include a command to set this timing, either long or short.

This new NX-OS release is available for download since beginning of September.


Now it was Ed: 

Would anyone happen to know if any of the ProCurve line have had an LACP timeout issue as well?  (e.g. 10s vs. 3s?)



And finally Herman answered and clarified some things: 

Just a couple clarification points:


LACP Fast (aka short) rate timer is 1 second with a timeout of 3 seconds

LACP Slow (aka long) rate timer is 30 seconds with a timeout of 90 seconds


There are no LACP timeout issues between VC and Procurve that I am aware of.   Also, I don’t know if there are any LACP issues between Procurve and Cisco. 


The issue that Armand describes below involves Cisco Nexus NX-OS version 4.1(3)N2(1a) and earlier negotiating LACP fast rate with its link partners yet not fully supporting the fast timer.  I.E.  the Nexus 5000 would send LACPDUs every 1 second but the proper assurance was not available in the code to guarantee transmission of those LACPDUs.  This could lead to LACP timeout problems with VC or other LACP partners that only requested fast rate.  Nexus 5000 NX-OS version 4.2(1)N2(1) adds a command to set ‘lacp rate fast’ on interfaces.




Any other comments or discussion?