1. A method comprising: supporting at least three protocol classes for a messaging protocol to be used for a cache coherence protocol for a plurality of caching agents, via at least three virtual channels provided by a link layer of a network fabric coupled to the caching agents; wherein the at least three virtual channels include a first virtual channel to support a probe message class, a second virtual channel to support an acknowledgment message class, and a third virtual channel to support a response message class; and the first virtual channel to be dependent on the second and third virtual channels, wherein the first virtual channel is dependent on the second and third virtual channels such that probe messages may be blocked until the second and third virtual channels become available; and sending a probe message from a requesting caching agent to a plurality of peer caching agents on the first virtual channel, and sending a request message corresponding to the probe message from the requesting caching agent to a home agent on the second virtual channel.