Unallocated prefix 100.10.10.0/24 in the DFZ via Cogent

Calling Cogent, Avantel (AS 6503) and Axtel (AS 14000): Axtel is announcing 100.10.10.0/24, which is within the 100.0.0.0/8 block, which is unallocated according to http://www.iana.org/assignments/ipv4-address-space/ I am seeing this from two of my transit providers, the common AS path is: 174 6503 6503 6503 6503 6503 14000 Prefix filtering is a good thing, please do it! Steinar Haug, Nethelp consulting, sthaug@nethelp.no