Exfo Electro-Optical Engineering Inc. of Quebec has signed an agreement to purchase the assets of Dallas-based gnubi communications LP, a supplier of network testing equipment. The agreement transfers gnubi's technology, expertise, customer base and inventories to Exfo in exchange for $2.5 million in Exfo stock and $1.8 million in cash and a cash earn-out based on sales volume. The acquisition of gnubi's multichannel test instrumentation could enhance Exfo's product portfolio for protocol-layer test equipment, which focuses on the network service provider market.