I read about ibm power7 processor and found this

"At the socket and system levels, advances in cache
Hierarchy, memory bandwidth, interconnect technology,
Coherence protocol, and significant core and cache power and
Area reduction allowed the transition from the two-core
POWER6 chip to the eight-core POWER7 chip while
Maintaining the balance of memory and snoop bandwidth per core."

I didn't got what it is.. please help me. I want to know what is snoop, snoop bandwidth and anything related to it.