Limitations
Segmented downloading technology cannot magically solve all downloading problems. There are mathematical constraints on the effectiveness of the technology.
In a group of users that has insufficient upload-bandwidth, with demand higher than supply. Segmented downloading can however very nicely handle traffic peaks, and it can also, to some degree, let uploaders upload "more often" to better utilize their connection.
Data integrity issues
- Very simple implementations of segmented downloading technology can often result in varying levels of file corruption, as there often is no way of knowing if all sources are actually uploading segments of the same file.
- Data corruption problems have led to most programs using segmented downloading using some sort of checksum or hash algorithm to ensure file integrity (to receive file intact) and uniqueness (to not receive bits of other similar files).
- Usually MD5 and SHA-1 hashes are preferred in most segmented download protocols, but CRC-64-ECMA would suffice in most cases. In cases where only MPEG files are being sent CRC-32-MPEG would also be acceptable.
- In the future most segmented downloading technologies will probably use layered hashes and checksums like WHIRLPOOL, SHA-256, SHA-512 and CRC-64-ECMA (for individual segments) to unquestionably guarantee data integrity. MD5 and SHA-1 have been determined to be cryptographically weak with respect to protecting data integrity.
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