Would Salesforce buying Slack be an offensive or defensive move?

Salesforce's deal to buy Slack is expected to be announced Tuesday after markets close, sources told CNBC's David Faber. The deal is expected to be about half cash and half stock, the sources said, and will price Slack at a premium. Dan Ives, managing director at Wedbush Securities, joins "Squawk Box" to discuss what a deal would mean for the two companies and the sector.