Virtual slot as a config master for LACP sharing

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Being a cisco guy, I am having some trouble with LACP sharing on XOS when I need to move a device (a switch or a server) to another group of ports. Since config master in XOS must be a sharing group member, I keep bumping into having to 'disable sharing', then 'enable' a new one and apply all the settings (vlans etc) all over again. Even worse when the ports overlap.
I made a feature request to create a new entity for LACP config master in XOS, but its being ignored so far. So I decided to do some magic.
All our Summits are in stacks. I have noticed one can have a config master on a non-present slot in stack. We can have up to 8 members in a stack topology, but we do not intended to go higher than 3. So, all I need to do is to create a slot 8 device with as many ports as I want to have LAGs. Then I create all my 'sharings' with a config master on that non-present slot. Now I can move member ports wherever I want - no config changes for config master.
So far this was tested in our lab and it looks good. However, before going into production with this crazy idea, I would like to be criticized by experienced Extreme professionals. What caveats are waiting for me in this configuration? Any better ideas to avoid the 'config master port' trouble&
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Maxim Rayevskiy

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Posted 3 years ago

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Prashanth KG, Employee

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Hi Maxim,


I hope I understand the situation right. If so, I think the above task can be accomplished by using the free ports in your stack using the following command,

configure sharing <master port> add ports <port-list>

This is a way to modify an existing sharing group and add additional ports to a group without needing to disable/enable the sharing group. 

Is this what you are looking for? 
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Maxim Rayevskiy

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Nope. The idea is different.
Supposing, I have a LAG with master port 1:1 and member ports 1:1 and 2:1. Suddenly, I need to move that device to ports 1:48 and 2:48.
There is no way in XOS to do it without service interruption. I need to create and configure new sharing 1:48 with member ports 1:48 and 2:48. I need to be very careful to transfer all port settings (vlans, stpd, etc). Then disconnect media from the old ports and connect to the new.

Now if I have a config master on virtual slot, then in the beginning I have a sharing 8:1 with members 8:1, 1:1 and 2:1. Then I add new ports:

configure sharing 8:1 add ports 1:48, 2:48

Then I disconnect media one-by-one from 1:1 and 2:1 and connect to 1:48 and 2:48. At any given time I have at least one active port in the sharing group. No service interruption!
And finally I remove the old ports:

configure sharing 8:1 del ports 1:1, 2:1
(Edited)
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Prashanth KG, Employee

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Got it! 

So, we are talking about creating a new sharing group with the new master port. In that case, I think yours is a pretty good work-around considering that you need to re-create the VLAN configuration to the new master-port whenever you are changing the ports. I can't think of any harm that it could cause in the production environment as long as slot 8 is not used at all except the software could report port 8:1 for FDB learning etc., 

This should work!
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Andrew Maldonado, Extreme Alumnus

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Maxim,

Creating a share group with the master port being a dedicated unused port may be the best approach at achieving the desired setup. Doing so will allow you to add and remove ports from the share group at will without having to lose the configuration associated with the share group.

I have not performed much testing with the master port being an unused port so it's hard to say what problems this can cause.

-Andrew