I thought the 7815s come with Broadcom Extreme gigabit nics. You may be able to get the same model.
The last Unity / CM upgrade that I did for one of my customers, they had 2 7815s and both had broadcom cards. So I think these cards are supported for IPCC as well
HTH
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Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus