OPEX and CAPEX are two important network design considerations. From the high level we should understand these two design requirements. OpEx refers to operational expenses such as support, maintenance, labor, bandwidth and utilities. Creating a complex network design may show off your technical knowledge but it can also cause unnecessary complexity making it harder to build, maintain, operate and manage the network. A well- designed network reduces OpEx through improved network uptime (which in turn can avoid or reduce penalties related to outages), higher user productivity, ease of operations, and energy savings. Consider creating the simplest solution that meets the business requirements. CapEx refers to the upfront costs such as purchasing equipment, inventory, acquiring intellectual property or real estate. A well-thought design provides longer deployment lifespan, investment protection, network consolidation and virtualization, producing non-measurable benefits such as business agility and business transformation and innovation, thus reducing risk and lowering costs in the long run. Last metric in the COST constraint is TCO (Total cost of ownership). TCO is a better metric than pure CapEx to evaluate network cost, as it considers CapEx plus OpEx. Make your network designs cost-effective in the long run and do more with less by optimizing both CapEx and OpEx. There are certainly other network design attributes such as Flexibility, security, modularity and hierarchical design. On the website, there are many other design requirements explained. If you find this post useful, please share your comment in the comment section. Author: Orhan Ergun CCIE/CCDE Trainer, Author of Many Networking Books, Network Design Advisor, and Cisco Champion 2019/2020/2021 He created OrhanErgun.Net 10 years ago and has been serving the IT industry with his renowned and awarded training. Wrote many books, mostly on Network Design, joined many IETF RFCs, gave Public talks at many Forums, and mentored thousands of his students. Today, with his carefully selected instructors, OrhanErgun.Net is providing IT courses to tens of thousands of IT engineers.