Excessive CRC/alignment errors

[graviton]

Our one and only core switch E5412zl has been logging continuous "Excessive CRC/alignment errors" on one fiber interface, which is connected to a v1910 switch on the remote side.

I have replaced all the physical components on both sides of the connection - transceivers (SFP GBICs), fiber patch cords, switch ports, and even the entire remote switch. I also used a different fiber pair from our switch room to an IDF (intermediate distribution facility), a buiding in-between the two ends of the connection, where the fiber cable that comes from our switch room (MDF) lands, before being distributed to several other campus buildings.

I am not able to replace the last little bit of fiber between the IDF and the final destination building, because there are no additional fiber pairs available. So there's a possibility that some defect exists on that last portion of fiber, including the connectors at both ends of that portion.

It may be helpful to know how other admins have dealt with this kind of issue. Any comments will be greatly appreciated.

[Richard Litchfield]

If it turns out there is a problem with the fibre, there are some nifty ProCurve optics that let you use a single fibre (ie 1 core) for the link rather than a pair. You need a matching up/down pair of optics - they act like a mini CWDM. If there are no spare fibres available, you might be able to use these.

With 2 pairs, you can effectively double the bandwidth from 1Gb to 2Gb over a 2-core link too.

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