portenable

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Can someone elaborate on the following command?  Below is all that I can find in the documentation.  i  know portadmin determines  if a port processes  BDBPs but what does portenable do?   


set spantree portenable


Use this command to set the port status on one or more Spanning Tree ports.
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Curtis Parish

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Posted 3 years ago

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Paul Poyant, Employee

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The following information is from a legacy KB article, and is being ported to a new GTAC Knowledge article. These commands operate on the 7100/S/N/K-Series products.

The 'set spantree portadmin <port-string> {enable | disable}' command will enable/disable the Spanning Tree protocol on a per-port basis as long as STP is globally enabled (this is the default). If per-port spantree portadmin is disabled, any received BPDUs will be discarded and no BPDUs will be transmitted out this port. This command has no effect if STP is globally disabled ('set spantree stpmode none').

The 'set spantree portenable <port-string> {enable | disable}' command will prohibit data traffic from being switched. However, operMAC will stay up and the port will still indicate link. Higher layer entities can still process traffic; but the traffic won't be learned/forwarded. If you want to shut the port down completely, you would instead use 'set port disable'. 
Note: There is no practical application that isn't met equally well using the 'set port disable' command, which engages the ifMIB to disable the interface. The spanning tree command is an artifact of an earlier time.
(Edited)
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Paul Poyant, Employee

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Curtis Parish

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"disables Spanning Tree on that port while also preventing traffic from being transmitted - but not preventing it from being received. "   

Thanks, that is one unusual command.  It bit me when I unintentionally  used portenable instead of portadmin.   
(Edited)
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Straw, Glyn, Employee

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The command does have a practical use ( set spantree portenable <port-string> disable ).

It is often used for Lag member ports to ensure that only the lag logical port (lag,0.1) can forward. The member ports will be set portenable disable so that they cannot forward independently of the lag.

Thus if there are connectivity issues and lacp protocol cannot maintain the lag, the member ports will never forward independently of the lag. The is prevents possibility of loops if protocols are failing. It also means clean failover to whatever other redundant path there is. 

Hope this helps
Glyn
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Curtis Parish

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Very useful information that needs to be included in the configuration guide.   Not sure why it is under spanning tree though.  Sounds like it should be in the LACP config tree. 
(Edited)
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Straw, Glyn, Employee

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yes , the positioning under spanning tree can be a little misleading. I think this is a historical thing but i agree we should look at getting this into the config guide if customers are not seeing it.

Thanks for the feedback
Best Regards
Glyn 
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It is also recommended in this article outlining some best practises for getting started with L2 config, in case this is useful for you ..

Browser View: https://gtacknowledge.extremenetworks.com/articles/How_To/EOS-Basic-Switch-Layer-2-Configuration-Best-Practices

Mobile View: https://gtacknowledge.extremenetworks.com/pkb_mobile#article/How_To/kA134000000LymfCAC/s

Please let us know if this article was helpful by submitting article feedback. Thanks!


Best Regards

Glyn