https://community.extremenetworks.com/t5/extremeswitching-vsp-fabric/vsp-7024-to-allied-telesis-at-x550-18xsq-via-sfp-mmf/m-p/68560#M812 Hi!<BR /><BR />Assuming fibers and SFP types match and are OK, you should check the auto negotiation settings, mainly speed and duplex but also auto-polarity. I've had some issues with Allied switches that will not come up if those are on auto on both sides. I can't remember what settings and which side we had to change (perhaps both) but that solved our problems.<BR /><BR />/Fredrik Tue, 31 May 2022 09:49:16 GMT FredrikB1 2022-05-31T09:49:16Z https://community.extremenetworks.com/t5/extremeswitching-vsp-fabric/vsp-7024-to-allied-telesis-at-x550-18xsq-via-sfp-mmf/m-p/68559#M811 Hi, a customer wants to connet a vsp 7024xls to an Allied Telesis AT-x550-18XSQ via SFP+ MMF. Fibre connection stays in down state. Patch Cable and SFP+ modules, changed, but no connection and no information in Log files. All ERS switches are connected succesfully.<BR />Has anyone done this already?<BR /><BR /> Mon, 02 May 2022 17:58:52 GMT https://community.extremenetworks.com/t5/extremeswitching-vsp-fabric/vsp-7024-to-allied-telesis-at-x550-18xsq-via-sfp-mmf/m-p/68559#M811 GuidoB 2022-05-02T17:58:52Z https://community.extremenetworks.com/t5/extremeswitching-vsp-fabric/vsp-7024-to-allied-telesis-at-x550-18xsq-via-sfp-mmf/m-p/68560#M812 Hi!<BR /><BR />Assuming fibers and SFP types match and are OK, you should check the auto negotiation settings, mainly speed and duplex but also auto-polarity. I've had some issues with Allied switches that will not come up if those are on auto on both sides. I can't remember what settings and which side we had to change (perhaps both) but that solved our problems.<BR /><BR />/Fredrik Tue, 31 May 2022 09:49:16 GMT https://community.extremenetworks.com/t5/extremeswitching-vsp-fabric/vsp-7024-to-allied-telesis-at-x550-18xsq-via-sfp-mmf/m-p/68560#M812 FredrikB1 2022-05-31T09:49:16Z