Cooperative Update Mechanism of Cache Update Method Based on Content Update Dynamic Queries for Named Data Networking
Takatoshi Miwa, Shigetomo Kimura · 2019
In Named Data Networking (NDN), a client requests a content object by its content identifier, instead of the server's IP address. When a router or a node around the client stores the content in the cache, it transfers the content from the cache. As a result, it is possible to provide information quickly and efficiently to many users. In NDN, a content distributor can configure the content's expiration time at each cache. The expiration time should be long enough to use the cache effectively and decrease the amount of traffic. However, if the expiration time is too long this increases the possibility of receiving old content. A shorter expiration time reduces this possibility but this causes the amount of traffic to increase instead. In order to solve this trade-off relationship, we proposed an automatic cache update method where each router queries the version number of all content in the cache to automatically remove old content. Since it is too difficult to set an appropriate inquiry interval for all the content, we also proposed a cache update method based on content update dynamic queries to dynamically change the inquiry interval when each content object is not updated. This paper improves this method by introducing a cooperative update mechanism to reduce the amount of traffic in the network and the number of times old content is received. It also evaluates the method on the generated topology that is similar to real topology and shows that, for example, when the cache size on all routers is large enough, although the difference in the average aggregated traffic is larger than that of the author's first method where the inquiry interval was 270 seconds by 49.1-84.9 GBytes for the experimental period (7 days) (= 4.9-8.4 MBytes per minute), the number of inquiries all routers generated is reduced by 131232.6- 1159687.9 times over 7 days (= 13.0-115.0 times per minute).