Data Sheet
Cisco 12000 Series OC-48c/STM-16c DPT Line Cards
The Cisco Dynamic Packet Transport (DPT) products define a new generation of transport technology—packet-optimized optical transport solutions. These solutions combine the bandwidth-efficient and services-rich capabilities of IP routing with the bandwidth-rich, self-healing capabilities of fiber rings to deliver fundamental cost and functionality advantages over existing solutions.
Cisco Systems, Inc. has developed the OC-48c/STM-16c DPT line card. DPT rings are dual, counter-rotating fiber rings. Both fibers are concurrently utilized to transport both data and control traffic as depicted in Figure 1.
Figure 1
Dynamic Packet Transport

Spatial Reuse Protocol
Spatial Reuse Protocol (SRP) is the media-independent Media Access Control (MAC)-layer protocol that enables DPT functionality in ring configurations. The SRP MAC provides the base functionality for addressing, packet stripping, bandwidth control, and control message propagation on the packet ring.
Transport Flexibility and Evolution
DPT rings run on a variety of transport technology, including Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH), wave-division multiplexing (WDM), and dark fiber. DPT provides carriers with the flexibility to operate packet rings over their embedded fiber transport infrastructure as well as an evolution path to packet-optimized transport for high-bandwidth IP networks. An OC-48c/STM-16c DPT node consists of two line cards. The line cards are connected via the MATE interface. Using two inter-connected line cards, the dual working fiber rings will maximize the bandwidth of both rings. Each DPT line card also provides the choice of single mode short- or long-reach optics to meet application requirements.
Spatial Reuse
DPT ring packet-processing procedures utilize destination stripping—packets are removed from the ring by the intended destination node instead of utilizing bandwidth around the entire ring. Thus, the DPT ring provides packet-by-packet spatial reuse wherein multiple segments can concurrently exchange traffic at full ring bandwidth without interference.
Ring Bandwidth Multiplication
DPT uses optimal path selection, spatial reuse, statistical multiplexing, and two working fibers to maximize the traffic —carrying capacity of the ring—and to minimize initial and growth costs. DPT rings also utilize the SRP Fairness Algorithm (SRP-fa) to ensure that both global fairness and local bandwidth optimization are delivered on all segments of the ring.
Transparent IP Service Extension
DPT provides an extensive set of packet-handling features to efficiently extend enhanced IP services over the metro area, including:
Proactive Monitoring and Robust Self-Healing
DPT combines powerful SONET/SDH overhead processing with Layer 2 management capabilities to deliver proactive, multilayer performance-monitoring, fault-detection, and fault-isolation capabilities. DPT provides sophisticated protection-switching capabilities for responsive self-healing via the Intelligent Protection Switching (IPS) algorithm. IPS enables sub-50-ms protection-switching performance for rapid IP service restoration and protection hierarchy to handle cases of multiple, concurrent degrade, failure, or maintenance events.
"Plug-and-Play" Operation
DPT rings utilize automatic procedures for address assignment and resolution, ring topology and status discovery, and control message propagation to optimize ring traffic routing and management procedures. Service providers can rapidly put DPT rings into operation and add and remove nodes from the ring while minimizing expensive and time-consuming configuration and provisioning requirements.
Figure 2
Cisco DPT Line Cards

DPT Ring Applications
DPT rings enable a key set of applications for service providers and large enterprises, including:
Table 1 Line Card Features and Benefits
Table 2 Line Card Part Numbers
|
Cisco IOS Software Release
Table 3 Optics Specifications
|
Layer 3 Packet Buffer Memory
Switch Fabric
LEDs
Physical Specifications
Environmental Specifications
For more information, please contact gsr-marketing@cisco.com