Shafik,
MPLS Forwarding Memory (LFIB) consumes one taginfo (64 Bytes) per route, plus one Forwarding Entry (104 Bytes) for each path
You can use the following command to find out how much memory is allocated by the LFIB.
"show memory allocating-process totals | include TFIB _tag"
Hope this helps,
Regards,
Harold Ritter, CCIE #4168 (EI, SP)