My standard in & out route filters are attached.
Everyone should use something like this.
--asp@partan.com (Andrew Partan)! Deny martian routes
! 1st and last classical B and C nets (guard nets).
access-list 180 deny ip 128.0.0.0 0.0.255.255 255.255.0.0 0.0.255.255
access-list 180 deny ip 191.255.0.0 0.0.255.255 255.255.0.0 0.0.255.255
access-list 180 deny ip 192.0.0.0 0.0.0.255 255.255.255.0 0.0.0.255
access-list 180 deny ip 223.255.255.0 0.0.0.255 255.255.255.0 0.0.0.255
In a classless environment, these prefixes are legitimate.
Correct behaviour is now known for these subnets and so I
wonder why you still have them in your standard list.