LACP not prioritizing desired ports

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LACP not prioritizing desired ports

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Re:LACP not prioritizing desired ports
2024-03-05 09:35:05

Hi @shivjm

Then here is my question, how do you verify that LACP does not prioritize these SFP ports?

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#12
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Re:LACP not prioritizing desired ports
2024-03-05 11:11:38 - last edited 2024-03-05 11:12:05

@Clive_A I can see that the LAG Table shows only the 1 GbE link whenever I restart switch B (see my screenshots from earlier) and I’ve verified with iperf3 that it is in fact using that link. I can also see the LAG Table update when I unplug the copper link, like in this screenshot from the passive side:

 

 

And I can see the difference in speed in iperf3 in that situation. Note that if I make the fiber links work like this and then plug the copper link back in, it doesn’t revert to using the copper link; it stays on the fiber links.

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#13
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Re:LACP not prioritizing desired ports -Solution
2024-03-07 01:26:27 - last edited 2024-03-08 01:27:17

Hi @shivjm 

Thanks for posting in our business forum.

shivjm wrote

@Clive_A I can see that the LAG Table shows only the 1 GbE link whenever I restart switch B (see my screenshots from earlier) and I’ve verified with iperf3 that it is in fact using that link. I can also see the LAG Table update when I unplug the copper link, like in this screenshot from the passive side:

 

 

 

And I can see the difference in speed in iperf3 in that situation. Note that if I make the fiber links work like this and then plug the copper link back in, it doesn’t revert to using the copper link; it stays on the fiber links.

So I confirmed this with the senior engineers, don't LAG two different ports of link speed at the same time. It does not work. You can set it but it won't take effect. There is a potential that the MAC address table would go in error.

So, if you set a LAG group, set the same link speed ports in the same LAG group. Don't mix them up.

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#14
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Re:LACP not prioritizing desired ports
2024-03-07 11:23:26

Thanks, @Clive_A. That’s disappointing—the Cisco documentation @KJK linked implies other vendors do support it, so I’m sad to see it’s not possible here. Fortunately, it’s not a major hindrance in this particular case since the 1 GbE link is only a failsafe. I suppose I can keep that port disabled as long as the two 10 GbE links are up.

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#15
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Re:LACP not prioritizing desired ports -Solution
2024-03-07 13:18:04 - last edited 2024-03-08 01:27:27

  @shivjm 

 

The switches that do not allow me to activate LACP on LAGs with links of different speeds are actually CISCO small business switches. When I try to do that, and I have never tried that before your post, I get an error message complaining about it and the switch accepts only the 1G port as a LAG candidate. The 10G ports are droped from the candidate list.

Kris K
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#16
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Re:LACP not prioritizing desired ports
2024-03-08 01:27:07

Hi @shivjm 

Thanks for posting in our business forum.

shivjm wrote

Thanks, @Clive_A. That’s disappointing—the Cisco documentation @KJK linked implies other vendors do support it, so I’m sad to see it’s not possible here. Fortunately, it’s not a major hindrance in this particular case since the 1 GbE link is only a failsafe. I suppose I can keep that port disabled as long as the two 10 GbE links are up.

So, see the KJK's reply. That kills the conversation and only increases your disappointment.

That looks like what an industry does. Not your, my, and our(company's) call. You probably check the standard and see if it is even possible from the theory instead of whining about it. Cisco as the leader in this industry does not do that, which might be impossible from the theory.

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#17
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Re:LACP not prioritizing desired ports
2024-03-08 07:34:57

@KJK, thanks, I appreciate the extra information (and your attempts to help me in general). I was going by the docs you shared, which I’ll quote here for reference in case anyone else is misled by them and comes to the same conclusion I did:

 

Any link operating at a different speed from the highest-speed active member or operating at half-duplex is made standby. All the active ports in a dynamic LAG operate at the same baud rate.


@Clive_A, if you consider it whining to use a word as mild and polite as ‘disappointing’, I think support may not be for you. I’m shocked to see this petulant and immature behaviour in a forum for business products, especially after the ordinary and fruitful conversation we’ve had in this thread. I’m under no obligation to genuflect at the altar of TP-Link’s engineering, and I don’t expect someone whom I’ve spoken to with courtesy and patience throughout to upbraid me for saying the conclusion is not the desired outcome. I definitely won’t be buying or recommending any more TP-Link products after your response.

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#18
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