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Will "configure elrp-client one-shot" actually disable ports or just log them?

  • 31 January 2019
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Userlevel 2
Assuming we used "configure elrp-client one-shot ports all print-and-log" as described in https://gtacknowledge.extremenetworks.com/articles/Q_A/Which-commands-can-be-used-to-detect-a-loop, will that command actually disable any ports or just print/log them so that they can be resolved before enabling ELRP?
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Best answer by Stephane Grosjean 1 February 2019, 20:54

I'd not configure ELRP on a Core switch (or just for logs to see the loops happening). This is a Edge protection. You should configure it at the edge, excluding the uplinks, and use egress for optimisation if you also do not configure ELRP on uplinks (not sending ELRP PDUs to the Core).

Egress is just defining what port to shutdown when a loop is detected : is it the one that generates it, or the one that received it?
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Userlevel 4
Hi Stephen,

By the provided command the switch will print the logs if loop is detected.
Userlevel 2
The "one-shot" worked as expected, but enabling ELRP didn't quite go as planned (or I am just misunderstanding how to configure it).

I enabled ELRP on egress for all ports on all VLANs using the command:
configure elrp-client periodic Desktops ports all log-and-trap disable-port egress duration 60

This was performed on our core switch and the desktop switch stack connected to it. I connected a cable between two ports on the desktop stack and both of those ports were disabled by ELRP. However, the core switch detected that loop on an attached stack and then disabled the uplink port to that stack. I thought that the "egress" method was meant to avoid that? Or is that only if we connect a device between the core switch and the desktop switch, and what we still need to do is exclude the uplink ports from ELRP?
Userlevel 7
I'd not configure ELRP on a Core switch (or just for logs to see the loops happening). This is a Edge protection. You should configure it at the edge, excluding the uplinks, and use egress for optimisation if you also do not configure ELRP on uplinks (not sending ELRP PDUs to the Core).

Egress is just defining what port to shutdown when a loop is detected : is it the one that generates it, or the one that received it?
Userlevel 2
Thanks. I set the core switch in each location to just log and trap so that we will get the notification but no action is taken. The switches that the desktops and phones connect to are set to log, trap, and disable for 60 seconds excluding the ports that uplink to the core.

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