Analyst Alex Henderson says pessimistic comments from PMC-Sierra are putting pressure on shares of Cisco's customers. He notes Cisco is a large buyer of PMC's chips, accounting for 25%-30% of PMC's revenues. As a result, Cisco shares came under pressure Friday. Henderson notes the effect of a slowing economy on demand, but thinks Cisco is aggressively cutting costs to deal with a tough environment. He thinks Cisco will use its substantial backlog to meet estimates until Q3 and Q4, when the firm will face more conservative revenue growth expectations. Henderson also thinks Cisco has the financial and operational strength to manage through this turbulent period.