UPDATE 2-GE, Comcast agree on NBC Universal valuation - source

* GE, Comcast agree on valuation of around $30 bln-source

* Vivendi not yet agreed to deal-source

* GE, Comcast agree on how to value JV after close-source

* Comcast cash payment to depend on NBCU performance-source (Adds background)

By Jui Chakravorty Das

NEW YORK, Nov 8 (Reuters) - General Electric Co (GE.N). and Comcast Corp (CMCSA.O) have agreed on a valuation of around $30 billion for a joint venture between NBC Universal and Comcast, ironing out what has been a key obstacle in talks so far, a source familiar with the matter said on Sunday.

The resolution of that issue brings the parties one step closer to an agreement, but French media conglomerate Vivendi (VIV.PA), which owns 20 percent of NBC Universal, has not yet agreed to a deal, the source said.

The source spoke on condition of anonymity because details of the discussions have not been made public.

GE, which owns 80 percent of NBC Universal, declined comment, as did Comcast. Vivendi was not immediately available for comment.