Unable to disable CRC check on Cisco 2960-X

[Shanali35k]

I have a 48 port Cisco 2960-X running IOS Version 15.0(2)EX5.

I'm trying to connect it to a Ubiquiti EdgeRouter4 using a Ubiquiti DAC Twinax cable..

I'm aware that this is technically not recommended, however:

It's for a homelab environment. I wouldn't do this for a production enterprise network, and I'm aware that Cisco do not recommend this, however - Cisco DACs are expensive.

When I plug the DAC in, I see the port come up in the logs, and them immediately go into an error state. Something to the effect of:

Jul  6 00:30:02.214: %GBIC_SECURITY_CRYPT-4-VN_DATA_CRC_ERROR: GBIC in port Gi1/0/50 has bad crc
Jul  6 00:30:02.218: %PM-4-ERR_DISABLE: gbic-invalid error detected on Gi1/0/50, putting Gi1/0/50 in err-disable state

I've tried running following this guide which suggests running:

• no errdisable detect cause gbic-invalid followed by:
• service unsupported-transceiver

As well as running service internal which I found here.

to disable CRC checks and enable the use of third-party transceivers in the switch. However, I'm still getting CRC errors. It feels like there's something else I need to do to enable third party SFP transceivers.

Is there something I'm missing? Or something else I can try?

[Leo Laohoo]

Try a different brand of 3rd party optics.  

[balaji.bandi]

First check the compatable matrix , is the DAC cable supports in 2960 ?

[Shanali35k]

I got the ans:

The giveaway is the port name Gi1/0/50. An SFP+ DAC generally requires an SFP+ (10G) port. There are very few SFP ports (1G) that accept SFP+ modules. unionwells

There are no SFP DACs, so you could use either a simple twisted-pair port (1000BASE-T), or SFP with multi-mode fiber (1000BASE-SX), or single-mode fiber (1000BASE-LX). If you do require 10G you'll need a 10G switch.

[balaji.bandi]

Glad  you have information now.