C3900-universalk9-mz.spa.157-3.m8.bin [updated] -

ip access-list standard MANAGEMENT-PERMIT permit 10.0.0.0 0.255.255.255 deny any log

The Cisco 3900 series, part of the ISR G2 (Generation 2) family, remains widely deployed in branch offices, enterprise campuses, and managed service provider edges. Key hardware features supported by this image include: C3900-universalk9-mz.spa.157-3.m8.bin

%SYS-2-MALLOCFAIL even at idle. Cause: 15.x universal images consume ~450MB of DRAM just to boot. If you have 1GB, you lose 512MB to the kernel, leaving little for routing tables. Fix: Upgrade DRAM to 2GB (Cisco part MEM-3900-2GB=). ip access-list standard MANAGEMENT-PERMIT permit 10