Web content coming from outside the ISP is today skyrocketing, causing significant additional infrastructure costs to network operators. The reduced marginal revenues left to ISPs, whose business is almost entirely based on declining flat rate subscriptions, call for significant innovation within the network infrastructure, to support new service delivery. In this paper, we suggest the use of micro CDNs in ISP access and back-haul networks to reduce redundant web traffic within the ISP infrastructure while improving user's QoS. With micro CDN we refer to a content delivery system composed of (i) a high speed caching substrate, (ii) a content based routing protocol and (iii) a set of data transfer mechanisms made available by content-centric networking. The contribution of this paper is twofold. First, we extensively analyze more than one month of web traffic via continuous monitoring between the access and back-haul network of Orange in France. Second, we characterize key properties of monitored traffic, such as content popularity and request cacheability, to infer potential traffic reduction enabled by the introduction of micro CDNs. Based on these findings, we then perform micro CDN dimensioning in terms of memory requirements and provide guidelines on design choices.