Working on LACP - Unifi

[zachre95]

I will provide details as needed but to keep thing's short and sweet... My LACP is "working" but its not "working"

Now to expand a little bit.

I enabled LACP on my Truenas server Both nic's are linked at 1Gb
LACP is enabled in UNIFI and on the server, i can reach the server just fine and both devices do register that LACP is enabled.

When moving files from PC1>Server it will use 1gb (understandable since i only have 1gb at the PC)
but
When i add in PC2 to the mix, theoretically (at least in my head unless i am confused on LACP) it should do 1GB from both PC's and the Truenas server should be pulling or delivering 1gb to both simultaneously?

Right now that is not the case. When i am moving a file from PC1 and PC2 at the same time, to write to the server, it will bring only saturate the 1GB link. Any assistance would be great as at this point im at a loss. I thought once i got the LACP negotiating and running on the network it would just work essentially as plug and play. Boy was i wrong. :)

Thanks anyone that takes the time to read this and lend me a hand!

 

[NickF]

Can you please elaborate on your testing methodology? Maybe also share a diagram?
Also important, what are the specs of your TrueNAS server?

 

[jgreco]

When moving files from PC1>Server it will use 1gb (understandable since i only have 1gb at the PC)
but
When i add in PC2 to the mix, theoretically (at least in my head unless i am confused on LACP) it should do 1GB from both PC's and the Truenas server should be pulling or delivering 1gb to both simultaneously?

No, that's not how LACP works. It's how you WANT LACP to work, it's how newbies IMAGINE LACP should work, but in reality it does not work that way.

Resource - LACP ... friend or foe?

Too many LACP discussions lately. Here's what you need to know. 1) Link aggregation groups are an interesting way to boost network throughput. They're typically managed by a protocol called Link Aggregation Control Protocol (LACP). Link...

www.truenas.com

LACP is mostly used on networks where there are maybe a dozen or more active clients so that the statistical chance of going over LinkA or LinkB ends up doing a good job of balancing the load.

Also, please use a standard notation such as "Gbps" and not "gb" and absolutely NOT "GB". This makes it hard to read your message.

 

[zachre95]

No, that's not how LACP works. It's how you WANT LACP to work, it's how newbies IMAGINE LACP should work, but in reality it does not work that way.

Resource - LACP ... friend or foe?

Too many LACP discussions lately. Here's what you need to know. 1) Link aggregation groups are an interesting way to boost network throughput. They're typically managed by a protocol called Link Aggregation Control Protocol (LACP). Link...

www.truenas.com

LACP is mostly used on networks where there are maybe a dozen or more active clients so that the statistical chance of going over LinkA or LinkB ends up doing a good job of balancing the load.

Also, please use a standard notation such as "Gbps" and not "gb" and absolutely NOT "GB". This makes it hard to read your message.

So just to clarify. If i am not mistaken LACP works in an environment where you may have multiple client's all reaching a single server it will split them up but if you have 1 client or 2 client's they will most likely be on the same ETH?

192.168.1.2---\
----------------->Eth1
192.168.1.3---/


192.168.1.4---\
----------------->Eth2
192.168.1.5---/

 

[jgreco]

So just to clarify. If i am not mistaken LACP works in an environment where you may have multiple client's all reaching a single server it will split them up but if you have 1 client or 2 client's they will most likely be on the same ETH?

192.168.1.2---\
----------------->Eth1
192.168.1.3---/


192.168.1.4---\
----------------->Eth2
192.168.1.5---/

No. LACP hashes header information in the ethernet packet and picks a link based on that. This is what we call "deterministic" in that the algorithm will always pick the same link if the data it hashes is the same. This leads to a situation where statistically speaking the chances of picking a path is 50% for any given hash, but the chance of an effective 50% traffic balance happening is also dependent on the other hashes being calculated. In addition, hashing is done in both directions. This means that if you have four clients, and you manage to devise a config that causes two on each link when transmitting, you might still find out that you get three-and-one (or even four-and-zero) on the return path traffic.

What this really means is that LACP usually isn't doing what people imagine it to be doing. It really only works well when you have a large number of clients all simultaneously talking to a server, so you get a good distribution of hash results.