private ip addresses from ISP

[adrian kok <adriankok2000 () yahoo com hk>]

Hi all

Have you had this experience?

Our router is running BGP and connecting to our
upstream provider with /30 network.   Our log reveals
that there are private IP addresses reaching our
router's interface that is facing our upstream ISP. 
How could this be possible?  Should upstream ISP be
blocking private IP address according to standard
configuration?  Could the packet be stripped and IP be
converted somehow during the transition? It happens in
many Tier-1 ISP though !

Thank you for your information