Everyone loves a reference sheet and this one is very helpful since GREP is so under utilized
The IBM 3800 Printing System, introduced in 1976, was a landmark in computer printing technology and is often regarded as the world’s first commercial laser printer. Designed primarily for high-volume data centers, the 3800 combined a laser imaging system with electrophotographic technology (similar to photocopying) and continuous-form paper feeding. It could print at an impressive rate of 20,000 lines per minute—roughly equivalent to 110 pages per minute—making it a revolution in automated document generation for large organizations like banks, insurance companies, and government agencies.
When it first launched, the IBM 3800 came with a hefty price tag. Depending on configuration and options, the system cost between **$250,000 and $500,000 USD** (equivalent to over $1 million today). However, IBM typically leased such machines to clients rather than selling them outright. This business model made sense for large-scale enterprise operations that required regular maintenance, consumables, and software integration. The printer’s cost was justified by its efficiency—it could replace multiple impact line printers and drastically reduce downtime and operating costs in large-scale print operations.
The 3800 also introduced several important innovations in digital printing. It was the first printer to take input directly from digital computer data, rather than relying on preformatted line print files, allowing for dynamic page layout and improved typographic control. The printer supported fonts and graphics stored in memory, a feature that paved the way for later desktop laser printers in the 1980s. Its use of continuous-form paper and integrated fuser technology made it highly reliable for round-the-clock operation, which was essential for industries producing daily billing statements or reports.
As for trivia, the IBM 3800 was so large it required its own dedicated room and environmental controls—it resembled more of a small car than a modern printer. It was also one of the first machines to use a **laser beam controlled by computer logic** to create images on a photoconductor drum, a concept that later became standard in laser printing. IBM continued developing the series through the 1980s, leading to successors like the 3800 Model 3, which improved resolution and reliability. Interestingly, some units remained in use well into the 1990s, a testament to their engineering quality and durability. The IBM 3800 is now remembered as the ancestor of modern laser and page printers, marking a major milestone in the evolution of digital printing technology.
Wireshark is an ideal tool for passive device discovery because it listens without touching the network — no probes, no ARP scans, no extra traffic that could disturb production systems. When you capture traffic at a mirror/span port or on an access point, Wireshark reveals the network “chatter” devices already send: discovery protocols (CDP/LLDP), DHCP exchanges, ARP, mDNS, and more. In your example, capturing a CDP packet from a Cisco switch instantly gave you device-identifying information (device ID, platform, capabilities) and the management IP address advertised in the CDP Address TLV — all without logging into the device or changing network state. That makes passive discovery low-risk and stealthy, especially useful in sensitive or stable environments where active scanning is unacceptable.
Beyond safety, passive captures give richer context than simple ping sweeps. A single CDP/LLDP frame can include the switch model, root/neighbor relationships, VLAN and port identifiers, and the management address — data that helps you map topology precisely. Wireshark’s decoders present those TLVs in human-readable form and you can quickly build an inventory: which switches are where, which devices advertise PoE capabilities, and which ports connect to what. Because you observe real traffic, you also learn about timing and frequency (how often devices advertise themselves), and you can correlate discovery with DHCP or ARP to see which IPs correspond to which MACs and which clients are actually active.
Finally, passive discovery with Wireshark aids troubleshooting, security and forensics. If a new, unexpected device appears on the network you can inspect the capture to see how it identified itself (hostname, vendor OUI in the MAC, CDP/LLDP info), whether it requested an IP via DHCP, and what services it announced. That speeds incident response and root-cause analysis. A short practical tip: apply display filters like `cdp` or `lldp` to quickly find discovery protocol frames, and expand the Address/Device-ID TLVs in the packet details pane to copy the management IP shown in the CDP packet. Always remember to capture only where you’re authorized to and respect privacy and policy when monitoring networks.
Being onsite gives you the opportunity to catch issues in real time before they become embedded problems. A quick glance at the rack would have immediately revealed that injectors were being installed, allowing for an instant correction instead of discovering it later.
I found this on ICT Developers - Kenya (Systems, Software, Web and Mobile Apps) facebook's group
https://www.facebook.com/groups/699308460212510/
