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Cisco Nexus 2148T Fabric Extender connectiviry issue to Juniper

Cisco Nexus 2148T Fabric Extender connectiviry issue to Juniper

Cisco Nexus 2148T Fabric Extender connectiviry issue to Juniper


Trying to connect the following:

Nexus 2148T FEX to a Juniper QFX5100-48T running Junos: 14.1X53.

It shows as the Physical Interface not coming up, even with just a basic config (i.e - Just enabling the ports on either end).

To test this we connected an sfp QFX5100 to the Nexus and it worked (although the port went into err-disabled due to BPDU Guard - expected though - we just wanted to check the physical).

We also connected the copper only QFX5100 (the one with the issues) to a simple T-Link switch and the ports came up okay.

We tried one 5100 to another 5100 and the ports came up okay.

So, physically, we know there is nothing wrong with the ports and also the cable is okay. So there must be an issue between the Nexus and the Juniper but don't know what (shwo int just says (Cable not connected)).

Anyone seen this behaviour please?


RE: Cisco Nexus 2148T Fabric Extender connectiviry issue to Juniper

It's okay. A colleague has solved this solution.

According to Juniper documentation, the "Auto-Negotiation" (as per most other vendors) is enabled by default. We found that it is, in fact, not enabled by default. Once this was enabled it all worked okay.

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