[c-nsp] SFP DOM SNMP Polling?

Jared Mauch jared at puck.nether.net
Tue Nov 22 15:35:47 UTC 2016

> On Nov 22, 2016, at 9:32 AM, Tim Durack <tdurack at gmail.com> wrote:
> I have a vendor that does not support SFP DOM SNMP polling. They state this
> is due to EEPROM read life cycle. Constant reads will damage the SFP.
> We SNMP poll SFP DOM from Cisco equipment without issue.
> Not heard this one before. Trying to see if there is some validity to the
> statement. Thoughts?

It’s entirely possible some people implement it poorly and the read cycles count.  With 100k cycles somewhat typical for those bytes, it’s certainly something that could be seen if polling every 5 minutes in 347 days, but I think that’s a datapoint that most SFPs are warranted for much longer than 347 days.

As the DDM data is stored not at 0x50 but at 0x51/0x52 in optics this is more likely done with a micro controller presenting the ram backed data via reads to/from those specific bytes.

- Jared

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