The maximum number of IP interfaces for 5420 Series is based on the following formulas:
If you disable the VRF scaling boot configuration flag:
# IP interfaces (248 max) + (# of VRRP IPv4 interfaces) + (# of VRRP IPv6 interfaces) + (# of RSMLT interfaces) + 2(if IP Shortcuts is enabled) + 3x(# of VRFs) + (#Anycast Gw VLANs if Anycast Gw router) = cannot exceed 248
If you enable the VRF scaling boot configuration flag:
# IP interfaces (max 248) + (# of VRRP IPv4 interfaces) + (# of VRRP IPv6 interfaces) + (# of RSMLT interfaces) + 2(if IP Shortcuts is enabled) + 3 + (#Anycast Gw VLANs if Anycast Gw router) = cannot exceed 248
For additional detail, see IP Interface Maximums Clarification.