Consider a network situation involving (only) Peer to Peer traffic in medium sized network.
For the sake of convenience, a simple P2P application like DC++ may be assumed, although I am aiming at a broader set involving torrents etc. too.
Peer A does a search for file qwerty.mp3, and then starts pulling the file, in pieces, from different Peers- B, C, D and E.
Now say Mr. C is the one who has shared this file amongst Peers, and he is a malicious peer and the file contains a malware/trojan etc.
Since the file is being downloaded in pieces from different Peers, it is unlikely that a standard Intrusion Detection system will be able to detect it since most of them involve signature-based detection techniques.
And most likely when the pieces are re-assembled at the system of Mr. A, his anti-virus will flag off a warning about the malicious content.
So, my question:
At the network level, what approach an admin may take so that innocent peers like A are protected from such situations?
Kindly do not suggest actions or measures relating to the end user. Whatever has to be done, must be done at the network level.
Please note that I am looking at this more from a research point of view and it is perfectly alright to not to point me towards existing techniques used in production environments but share links for research papers and give answers which tell of an open-ended techniques.