# How Actor & partner election happening in LACP protocol



## nmskarthik

Hi,

Can some one help me to understand the concepts of Actor & partner in LACP. What basis switch will move to actor or partner?

With Regards,
karthik.N


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## Wand3r3r

perhaps you mean Active and Passive?

Link aggregation - Wikipedia, the free encyclopedia


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## nmskarthik

Hi wand3r3r,

I didn't mean active & passive.

Active & passive modes will be related to link between two switches.What i need is out of the two switches one will be actor & the other one is a partner. How that election is happening?

With Regards,
karthik.N


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## Wand3r3r

After the exchange of a few LACPDUs, the actor and the partner should have agreed on each other's status, and verified that each has correctly recognized the other's status (by checking the values that the other device is sending in the 'partner' fields of the LACPDUs). Once the actor and partner have come to agreement about each other's settings, the devices can make a decision about whether the ports at each end of the link can be added to an aggregation.


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## nmskarthik

Hi,

Thanks,

I know the concept that after few BPDU exchange one will become actor and other will become partner.Is it possible to know how many LACPDU will be transfer between those switches to achieve this. 

If both the switches are started at the same time which one will become actor, what are the parameters used?

Please help me to understand this in depth.

With Regards,
karthik.N


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## Wand3r3r

Perhaps this will help

How to Configure, Verify, and Debug Link Aggregation Control Protocol_°Ù¶ÈÎÄ¿â

"Please help me to understand this in depth."
Sorry but I am not a professor. You should be asking yours the questions you can't find answers to.


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## CCSmooth1

I know this post is old but i came across it because I was asking the same question. From what I can tell the local switch running lacp will always see itself as the "actor" and will always see its neighbor as the "partner." I will post some text from the outputs on my CCNP lab to show you what I am talking about:

CCNP3750-1#sh lacp int det
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode

Channel group 1

Actor (internal) information:

*Actor Actor Actor
Port System ID Port Number Age Flags
Fa1/0/1 65535,001e.1361.9400 0x104 9s SA*

LACP Actor Actor  Actor
Port Priority Oper Key Port State
32768 0x1 0x3D

Port State Flags Decode:
Activity: Timeout: Aggregation: Synchronization:
Active Long Yes Yes

Collecting: Distributing: Defaulted: Expired:
Yes Yes No No


as you can see eventhough the system priority on this particular switch is maxed out, it still views itself as the "Actor" Now look at how it views its neighbor:

CCNP3750-1#sh lacp nei det
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode

Channel group 1 neighbors

Partner's information:


* Partner Partner Partner
Port System ID Port Number Age Flags
Fa1/0/1 32768,001f.2792.aa00 0x104 21s SP
*
LACP Partner Partner Partner
Port Priority Oper Key Port State
32768 0x2 0x3C

Port State Flags Decode:
Activity: Timeout: Aggregation: Synchronization:
Passive Long Yes Yes

Collecting: Distributing: Defaulted: Expired:
Yes Yes No No


As you can see it sees its neighbor as the "partner"

Now look at what happens when I go to the "Neighbor" switch:

CCNP3750-2#sh lacp int det
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode

Channel group 2

*Actor (internal) information:

Actor Actor Actor
Port System ID Port Number Age Flags
Fa1/0/1 32768,001f.2792.aa00 0x104 25s SP
*
LACP Actor Actor Actor
Port Priority Oper Key Port State
32768 0x2 0x3C

Port State Flags Decode:
Activity: Timeout: Aggregation: Synchronization:
Passive Long Yes Yes

Collecting: Distributing: Defaulted: Expired:
Yes Yes No No

CCNP3750-2#sh lacp nei det
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode

Channel group 2 neighbors

Partner's information:


* Partner Partner Partner
Port System ID Port Number Age Flags
Fa1/0/1 65535,001e.1361.9400 0x104 8s SA*

LACP Partner Partner Partner
Port Priority Oper Key Port State
32768 0x1 0x3D

Port State Flags Decode:
Activity: Timeout: Aggregation: Synchronization:
Active Long Yes Yes

Collecting: Distributing: Defaulted: Expired:
Yes Yes No No


As you can see the same situation exists. There really is no election per se, each switch views itself as the "Actor" locally. This whole concept of "Actor" and "Partner" is really to just decide on whether or not the ports are compatible to form the LACP EC. It appears that these roles are locally significant.

HTH

Chris.


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