topic RE: ELRP and STP x450e in ExtremeSwitching (EXOS/Switch Engine)

ELRP and STP x450e

Andrew_Schulz — Sat, 21 Nov 2015 06:37:00 GMT

I have 1 x450e acting as a core switch and 5 more that are trunked to the core; a basic hub and spoke topology. I don't believe there is a loop in this design, but my question is do I need to run STP or ELRP here? Can someone give me some best practices as it relates to preventing loops or other issues with this topology?

Thanks

RE: ELRP and STP x450e

Patrick_Voss — Sat, 21 Nov 2015 07:01:00 GMT

Hi Andrew,

with a hub and spoke setup STP should not be required but it really is a matter of opinion. If the setup is all Extreme then ELRP will work just fine. Here is an article that provides a basic configuration for ELRP:

https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-ELRP-to-disable-ports

Hope this helps!

RE: ELRP and STP x450e

davidj_cogliane — Sat, 21 Nov 2015 07:08:00 GMT

Andrew, If it is a hub and spoke design I would: create vlan "noloop" and add it to every port tagged Add all your uplink ports to the elrp excluded list on their respective switches. In our designs configure elrp to permanently disable ports when a loop is detected. This will protect you from people plugging loops in and prevent your uplinks from being taken down by the loop.

RE: ELRP and STP x450e

Andrew_Schulz — Sat, 21 Nov 2015 07:17:00 GMT

Thanks for the quick reply. I did see the article on ELRP; another question on that, do I apply it only on the uplink from the access switches or just the ports on the core that the access switches trunk too or both?

Sorry, for the basic questions, I'm a bit new to this.

Thanks.

RE: ELRP and STP x450e

Andrew_Schulz — Sat, 21 Nov 2015 07:20:00 GMT

I think I know the answer to that, but to confirm. I set ELRP on all ports and disable it on the uplink on all switches????

RE: ELRP and STP x450e

Patrick_Voss — Sat, 21 Nov 2015 07:21:00 GMT

It is recommended to apply ELRP on all the ports in each VLAN then exclude the uplink ports. I would do this on ALL switches because it will be easier to track down where the loop is if there is one.

RE: ELRP and STP x450e

davidj_cogliane — Sat, 21 Nov 2015 07:22:00 GMT

You would want it on both ends of the link. Any port with the vlan you are using will get disabled unless it is on the excluded list.

RE: ELRP and STP x450e

Andrew_Schulz — Sat, 21 Nov 2015 07:22:00 GMT

Perfect, thank you for confirming that, and thank you for the assistance.

RE: ELRP and STP x450e

Bill_Stritzinge — Sat, 21 Nov 2015 18:42:00 GMT

Andrew,

ELRP goes great on the edge facing ports, it is simple to monitor and simple to configure and works great. All you would do is enable ELRP on the vlans (must configure for each vlan if tagged) and ports pointing toward your edge devices, the only real decision is what you want to do when a loop occurs, your options are: 1. take no action and log; 2. log and disable port permanently; 3. log and trap and disable port for a duration time and any combination in between. In most cases like a education installation we will disable port permanently so the admins have to take action and manually re-enable the port(s). The best thing about ELRP is its ability to find a loop several switches down, something STP Edge Safeguard cannot do.

Here is a link to the user guide regarding detailing more info and configuration examples: http://documentation.extremenetworks.com/exos/EXOS_All/Troubleshooting/t_configure-standalone-elrp.s...