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This chapter describes the DPT port adapter and contains the following sections:
The DPT port adapter shown in Figure 1-1 is a dual-width OC-12c port adapter that provides a shared IP over SONET capability in a Cisco 7200 series, Cisco uBR7246, or Cisco 7200 VXR router. The DPT port adapter is available in four models:
The DPT port adapter provides Cisco 7200 series, Cisco uBR7246, or Cisco 7200 VXR routers with two SC duplex ports. Each SC duplex port provides the physical connection to an adjacent device in a DPT ring.
The DPT port adapter is designed to be deployed in SONET OC-12 DPT rings. DPT rings can also be connected to SONET Add Drop Multiplexers (ADMs), thus allowing for the creation of small or very large DPT rings.
The DPT port adapter supports the following functions:
The following terms and acronyms are used in this publication:
Spatial Reuse Protocol (SRP) is a media-independent MAC layer protocol that operates over two counterrotating fiber-optic rings. The dual rings provide survivability of data in case of a failed node or a break in connecting cables by rerouting the data path over the alternate ring. SRP provides a more efficient use of bandwidth by having packets traverse only the part of the ring necessary to get to the destination node. Once the packet has reached the destination node, it is removed from the ring, allowing other parts of the ring to reuse the bandwidth. Data packets travel on one ring, while associated control packets travel in the opposite direction on the alternate ring, ensuring that the data takes the shortest path to its destination. (See Figure 1-2.)
Each node on a DPT ring represents a Cisco 7200 series router, Cisco uBR7246, Cisco 7200 VXR, Cisco 7500 series router, or a Cisco 12000 series Gigabit Switch Router (GSR). A Cisco 7200 series, Cisco uBR7246, Cisco 7200 VXR, or Cisco 7500 series router can be used as an aggregation device for the Cisco 12000 series GSR. The Cisco 7200 series, Cisco uBR7246, Cisco 7200 VXR, or Cisco 7500 seires router collects data from lower-speed interfaces and passes it to the Cisco 12000 series GSR. Typically, more Cisco 7200 series, Cisco uBR7246, Cisco 7200 VXR, or Cisco 7500 series routers aggregate traffic toward fewer Cisco 12000 GSRs.
A DPT ring can contain up to 32 nodes at one time, with each node holding a map of the ring topology that it continually updates to ensure that data takes the shortest path to its destination. The frequency of the updating can be manually configured. See the "Configuring the DPT Topology Feature" section.
The DPT interface uses the SONET ring architecture, which provides redundancy and protection from a failed node or fiber cut through the use of the Intelligent Protection Switch (IPS). When the DPT ring topology changes because of a node failure, as shown in Figure 1-3, the system software automatically puts the node into pass-through mode, where data continues to pass through the node, but the node is no longer seen on the ring topology map. In the event of a fiber cut, ring wraps are created to redirect data traffic over the alternate ring. (See Figure 1-4.)
In both pass-through mode and wrap mode, data packets not destined for the affected node still reach their destination.
The SONET specification for fiber-optic transmission defines two types of fiber: single-mode and multimode. Signals travel farther through single-mode fiber than through multimode fiber.
The maximum distance for single-mode installations is determined by the amount of light loss in the fiber path. Good-quality single-mode fiber with very few splices can carry an OC-12c/STM-4 signal 50 miles (80 kilometers) or more. Good-quality multimode fiber can carry the signal up to 1640 feet (500 meters). If your environment requires the signal to travel close to the typical maximum distance (as listed in Table 1-1), use an optical time-domain reflectometer (OTDR) to measure the power loss.
| Cable | Power Budget | Transmit Power | Receive Power | Typical Maximum Distance |
|---|---|---|---|---|
Single-mode intermediate range | 12 dB | -28 to -8 dBm | 9.3 miles (15 km) | |
Single-mode long range | 25 dB | -3 to 2 dBm at | -28 to -8 dBm | 24.8 miles (40 km) |
Single-mode extended reach | 25 dB | -2 to 3 dBm at 1550 nm | -28 to -7 dBm | 50 miles (80 km) |
Multimode | 6 dB | -20 to -14 dBm at 1270 to 1380 nm | -26 to -14 dBm | 1640.4 feet (500 m) |
| 1dBm = decibels per milliwatt 2nm = nanometer |
The eight LEDs on the faceplate of the DPT port adapter (see Figure 1-1), show the DPT port adapter status, as well as the status of the individual ports. Table 1-2 explains the DPT port adapter LEDs.
| LED Label | Color | State | Function |
ENABLED | Green | On | Indicates that the DPT port adapter is enabled for operation; however, the interface port might be in the shutdown state. |
PASS-THROUGH | Amber | On | Indicates the DPT port adapter is in a pass-through state. |
RX PKTS | Green | On | Indicates the DPT port adapter has received a packet. This LED flickers in normal operation, indicating traffic. |
RX CARRIER | Green | On | Indicates the DPT port adapter has detected valid SONET or SDH framing on the received carrier. |
ACTIVE | Green | On | Indicates that side A or B of the DPT port adapter is functioning. |
Use a single-mode or multimode fiber-optic interface cable to connect your Cisco 7200 series, Cisco 7200 VXR, or Cisco uBR7246 router to another router or switch. In general, multimode cables are gray or orange, and single-mode cables are yellow.
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Note Single-mode and multimode fiber-optic cables are not available from Cisco Systems. |
For SONET or SDH single-mode and multimode fiber-optic connections, use one duplex SC-type connector (see Figure 1-6) or two simplex SC-type connectors. (See Figure 1-7.)
Attach either one duplex fiber cable or two simplex fiber cables between the DPT port adapter and the device to which the DPT port adapter is connected. Observe the receive (RX) and transmit (TX) cable relationship shown in Figure 1-8.
The following warnings apply when you work with fiber-optic cable ports.
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Warning Because invisible radiation may be emitted from the aperture of the port when no fiber cable is connected, avoid exposure to radiation and do not stare into open apertures. |
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Warning Class 1 laser product (single-mode). |
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Warning Class 1 LED product (multimode). |
This section discusses port adapter slot locations on the supported platforms. The illustrations that follow summarize slot location conventions on each platform.
Figure 1-9 shows a Cisco 7206VXR with a DPT port adapter installed in port adapter slots 3 and 4. In the Cisco 7206 and Cisco 7206VXR port adapter slot 1 is in the lower left position, and port adapter slot 6 is in the upper right position. (The Cisco 7202 and Cisco 7204 are not shown; however, the DPT port adapter can be installed in any two horizontally aligned port adapter slots.)
Figure 1-10 shows the slot numbering of port adapters in a Cisco uBR7246 router. The port adapter slots are numbered slot 1 and slot 2 for the Cisco uBR7246. (Slot 0 is always reserved for the Fast Ethernet port on the I/O controller—if present.)
This section describes how to identify interface addresses for the DPT port adapter in supported platforms. Interface addresses specify the actual physical location of each interface on a router or switch.
Interfaces on the DPT port adapter installed in a router maintain the same address regardless of whether other port adapters are installed or removed. However, when you move a port adapter to a different slot, the first number in the interface address changes to reflect the new port adapter slot number.
Table 1-3 explains how to identify interface addresses of a DPT port adapter.
| Platform | Interface Address Format | Numbers | Syntax |
|---|---|---|---|
Cisco 7200 series and Cisco 7200 VXR routers | Port-adapter-slot-number/interface-port-number | Port adapter slot—1, 3, or 5 for the DPT port adapter (depends on the number of slots in the router)1 Interface port—always 0 | 1/0 |
Cisco uBR7246 router | Port-adapter-slot-number/interface-port-number | Port adapter slot—always 11 for the DPT port adapter Interface port—always 0 | 1/0 |
| 1Port adapter slot 0 is reserved for the Fast Ethernet port on the I/O controller (if present). |
This section describes how to identify the interface addresses used for the DPT port adapter in Cisco 7200 series, Cisco 7200 VXR, or Cisco uBR7246 routers. The interface address is composed of a two-part number in the format port-adapter-slot-number/interface-port-number. See Table 1-3 for the interface address format.
In Cisco 7200 series and Cisco 7200 VXR routers, port adapter slots are numbered from the lower left to the upper right, beginning with port adapter slot 1 and continuing through slot 4 for the Cisco 7204 and Cisco 7204VXR, and slot 6 for the Cisco 7206 and Cisco 7206VXR. (Port adapter slot 0 is reserved for the optional Fast Ethernet port on the I/O controller—if present.)
The interface address of the DPT port adapter in slots 1 and 2 is 1/0 (port adapter slot 1 and interface 0). If the DPT port adapter was in port adapter slots 3 and 4 this same interface would be numbered 3/0 (port adapter slot 3 and interface 0).
In Cisco uBR7246 router, port adapter slots are numbered slot 1 and slot 2 for the Cisco uBR7246 and Cisco uBR7246VXR. (Slot 0 is always reserved for the Fast Ethernet port on the I/O controller—if present.) The individual interfaces always begin with 0. The number of additional interfaces depends on the number of interface ports on a port adapter.
The interface addresses of the interfaces on a DPT port adapter are 1/0 and 1/1 (port adapter slot 1 and interfaces 0 and 1).
Posted: Mon Aug 28 11:15:36 PDT 2000
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