When using this in GNS3, ensure you calculate an "Idle-PC" value. This prevents the emulated router from consuming 100% of your computer's CPU while the router is idle.
Cisco software is proprietary. Officially, you should download IOS images from the portal. To do this, you generally need: A valid Cisco Connection Online (CCO) ID. c3725-adventerprisek9-mz.124-15.t14.bin download
This indicates the hardware platform, the Cisco 3725 multiservice router. When using this in GNS3, ensure you calculate
This tells us the file is RAM-based (m) and compressed (z). When using this in GNS3
An active service contract (SmartNet) associated with your account for that specific hardware series. Laboratory & Learning Use
This is the feature set. "Advanced Enterprise Services" includes everything from basic IP routing to advanced security (K9 indicates strong encryption), voice, and MPLS features.