Cisco CAB-OCTAL-MODEM
Octal Cable with Male DB25 Connectors, Original Cisco
Product Highlights
Managing out-of-band console access or dial-in connectivity across multiple devices demands reliable, purpose-built cabling — and improvised solutions waste time and introduce failure points.
The Cisco CAB-OCTAL-MODEM (Cisco part number 72-0990-01) is an 8-lead octal breakout cable that converts a single 68-pin HPDB (SCSI II) port into eight male DB-25 modem connections. Commonly referred to as an "octopus" cable, it is designed for connecting Cisco access servers and routers equipped with high-density asynchronous interfaces directly to modem banks, terminal servers, or other DCE serial devices with DB-25 ports.
The CAB-OCTAL-MODEM is compatible with the Cisco 2509 through 2512 access server series as well as the NM-16A and NM-32A high-density asynchronous network modules used in the Cisco 2600 and 3600 Series Routers. At 10 feet (3 meters) in length with 28 AWG copper conductors, it provides the reach and signal quality needed for clean rack-to-rack modem connectivity. Unlike the CAB-OCTAL-ASYNC variant that terminates in RJ-45 connectors, the CAB-OCTAL-MODEM terminates directly in male DB-25 plugs — eliminating the need for separate modular adapters when connecting to DB-25 modem equipment.
Features & Benefits
8-Way Octal Breakout
The CAB-OCTAL-MODEM fans out from a single 68-pin HPDB connector into eight individual leads, each terminated with a male DB-25 connector. This allows a single high-density async port on your Cisco router or access server to serve eight separate modem or serial device connections, maximizing port density without additional hardware.
Direct DB-25 Modem Connectivity
Each of the eight leads terminates in a male DB-25 connector wired for modem (DCE) connectivity. This means you can plug directly into modem banks, CSU/DSUs, or other DB-25 serial equipment without purchasing separate RJ-45-to-DB-25 adapters — reducing parts count and potential points of failure.
Broad Cisco Platform Compatibility
The cable is designed for use with Cisco access servers (2509–2512) and the NM-16A and NM-32A high-density asynchronous network modules found in Cisco 2600 and 3600 Series Routers. Whether you're building a dial-in access solution or an out-of-band management infrastructure, this cable integrates seamlessly with established Cisco async platforms.
Reliable Copper Construction
Built with 28 AWG copper conductors across a 10-foot (3-meter) length, the CAB-OCTAL-MODEM delivers dependable signal integrity for asynchronous serial communication. The cable is engineered to Cisco's original specifications (part 72-0990-01), ensuring consistent performance in production environments.
Deployment Scenarios
Dial-In Access Server Deployment
Connect a Cisco 2509, 2510, 2511, or 2512 access server to a rack of external modems for dial-in remote access. The CAB-OCTAL-MODEM provides all eight modem connections from a single 68-pin port, simplifying cabling and reducing clutter in the rack.
Out-of-Band Network Management
Use the cable with NM-16A or NM-32A async modules in Cisco 2600 or 3600 Series Routers to establish out-of-band console access to remote network devices via modem dial-up. Each DB-25 lead connects to a modem that in turn connects to a remote device's console port.
Legacy Serial Device Integration
Connect Cisco async interfaces to legacy serial equipment such as terminal servers, data collection devices, or industrial controllers that use DB-25 serial ports. The octal cable consolidates eight connections into a single managed interface.
General
Connectors
Physical
Compatibility
Compatibility Notes
Compatible Cisco Platforms
- Access Servers: Cisco 2509, 2510, 2511, 2512
- Network Modules: NM-16A, NM-32A (high-density asynchronous modules for Cisco 2600 and 3600 Series Routers)
Connector Details
- Router/Module End: 68-pin HPDB (SCSI II) Male
- Device End: 8 x DB-25 Male (modem/DCE wiring)
Important Notes
- This cable terminates in male DB-25 connectors wired for modem (DCE) connections. If your target devices have RJ-45 console ports instead of DB-25 ports, consider the CAB-OCTAL-ASYNC (RJ-45 termination) or CAB-OCTAL-KIT (RJ-45 cable with DB-25 adapters) instead.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| CAB-OCTAL-ASYNC | Cisco Octal Cable (HPDB 68 to 8x RJ-45) | Terminates in 8 RJ-45 connectors instead of DB-25 — ideal for connecting to devices with RJ-45 console ports. |
| CAB-OCTAL-KIT | Cisco Octal Cable Kit (Cable + 8 DB-25 Adapters) | Includes the CAB-OCTAL-ASYNC cable bundled with 8 RJ-45-to-DB-25 male modular adapters for maximum flexibility. |
| CAB-OCTAL-FDTE | Cisco Octal Cable with Female DB-25 DTE Adapters | Includes 8 RJ-45-to-DB-25 female DTE adapters — use when connecting to DCE devices with male DB-25 ports. |
| CAB-OCTAL-9DTE | Cisco Octal Cable with DB-9 Female DTE Adapters | Includes 8 RJ-45-to-DB-9 female adapters — suited for devices with DB-9 serial console ports. |