A Fast Bloom Filters Method in APN Filtering

APN (access point name) is a valuable parameter for charge in the third generation (3G) communication. So the APN filtering check GTP protocol messages to determine if a roaming subscriber is allowed to access a specified external network which is an important function in 3G security device. The length of APN character and indefinite length matching are two difficulties for some Trie tree algorithms. Bloom filter is a fast method for approximate matching. But the LSF method of streaming data is affected by the maximum length of the characters. Too long characters may increase the matching times and reduce the matching speed. A fast APN filtering method which uses the feature of APN to partition by the character-dot is shown. The method has a two-stage structure Bloom filters (TSBF method). The first stage is to match the first string of the suffixes in the APN filtering list. The second stage is to match the whole suffixes. The realization of the APN filtering used TSBF is introduced. And the experiments show the TSBF has better performance than the LSF method.