Cisco Fundamentals for DevOps — Trivia & Interesting Facts¶
Surprising, historical, and little-known facts about Cisco and its foundational networking technologies.
Cisco was founded by two Stanford employees who just wanted to email each other¶
Leonard Bosack and Sandy Lerner, who worked in different departments at Stanford, couldn't easily communicate between their respective department networks. They built a multi-protocol router in 1984 to connect the networks, and that router became the foundation of Cisco Systems. The name "Cisco" is short for San Francisco, and the logo represents the Golden Gate Bridge.
IOS originally stood for "Internetwork Operating System"¶
Cisco's IOS was one of the first network operating systems to support multiple routing protocols simultaneously. It ran on a monolithic architecture — a single memory space with no process isolation — which meant a bug in any component could crash the entire router. This architectural debt haunted Cisco for decades and drove the creation of IOS-XR (modular, Linux-based) and IOS-XE (Linux-hosted).
The Cisco CLI syntax became an industry standard by sheer market dominance¶
There is no RFC or standard defining the "enable, configure terminal, interface GigabitEthernet0/1" command structure. It became the de facto standard because Cisco held 70-80% of the enterprise router and switch market through the 1990s and 2000s. Nearly every other vendor — Arista, Juniper's set-style CLI, and even open-source projects like VyOS — adopted variations of Cisco's command hierarchy because that's what network engineers already knew.
CDP was Cisco's answer to a problem that shouldn't have existed¶
Cisco Discovery Protocol (CDP) lets directly connected Cisco devices learn about each other's identity, platform, and capabilities. It was proprietary and Cisco-only, which eventually forced the IEEE to standardize LLDP (802.1AB) as a vendor-neutral alternative. Many networks today run both protocols simultaneously, wasting a small amount of bandwidth on duplicate advertisements.
The CCNA certification created the modern network engineering profession¶
Before Cisco launched the CCNA in 1998, there was no widely recognized credential for network engineering. The CCNA and its higher tiers (CCNP, CCIE) established a career ladder that defined what network engineers should know. At its peak, the CCIE was one of the most respected and difficult certifications in all of IT, with a lab exam pass rate rumored to be around 20-30%.
Cisco's 6500 switch was the backbone of the Internet for over a decade¶
The Catalyst 6500 series, launched in 1999, became one of the most widely deployed chassis switches in history. It was used as a campus distribution switch, data center aggregation, and even as an Internet backbone router when equipped with Sup720 supervisors. Some 6500s ran continuously for 10+ years. The platform was so entrenched that migrating off it became a multi-year project at many enterprises.
The "router on a stick" pattern was born from Cisco's inter-VLAN routing¶
Before Layer 3 switches were common, the only way to route between VLANs was to trunk all VLANs to a router's single physical interface using 802.1Q sub-interfaces. This "router on a stick" topology became a Cisco certification staple. The performance was terrible — all inter-VLAN traffic had to traverse the trunk link twice — but it worked and taught a generation of engineers how VLANs and routing interact.
Cisco NX-OS was built on Linux from the start¶
When Cisco designed NX-OS for the Nexus data center switches (2008), they broke from the monolithic IOS tradition and built it on a Linux kernel with a modular process architecture. Each protocol (BGP, OSPF, etc.) runs as a separate Linux process. This was a direct admission that the monolithic IOS model couldn't meet the reliability demands of modern data centers.
The "no shutdown" command is one of the most consequential defaults in networking history¶
Cisco interfaces default to the "shutdown" state, requiring an explicit "no shutdown" to activate. This design decision has prevented countless accidental network loops from newly-cabled interfaces, but has also caused an equal number of troubleshooting sessions where the answer was simply "you forgot no shut." Every network engineer has this story.
Cisco's acquisition strategy reshaped the entire networking industry¶
Between 1993 and 2020, Cisco acquired over 200 companies. Many core Cisco technologies were not built in-house: the PIX firewall came from Network Translation Inc., WebEx from WebEx Communications, Meraki from Meraki (MIT spinoff), AppDynamics, Duo Security, ThousandEyes, and Splunk. This buy-and-integrate strategy made Cisco the networking conglomerate it is today.