Table of Contents 1 E-CPOS Interface Configuration 1-1

Transcription

1 Table of Contents 1 E-CPOS Interface Configuration 1-1 Overview 1-1 SONET 1-1 SDH 1-1 E-CPOS 1-5 Configuring an E-CPOS Interface 1-6 Configuring an E-CPOS Interface 1-6 Configuring the Operating Mode of an E-CPOS Interface/Channel 1-7 Displaying and Maintaining E-CPOS Interfaces 1-8 E-CPOS Interface Configuration Example 1-8 E-CPOS Interface Configuration Example 1-8 Troubleshooting E-CPOS Interfaces 1-9 Symptom 1-9 Solution 1-9 i

2 1 E-CPOS Interface Configuration When configuring an E-CPOS interface, go to these sections for information you are interested in: Overview Configuring an E-CPOS Interface Displaying and Maintaining E-CPOS Interfaces E-CPOS Interface Configuration Example Troubleshooting E-CPOS Interfaces Overview SONET Synchronous Optical Network (SONET), a synchronous transmission system defined by the ANSI, is an international standard transmission protocol over fiber-optic. SONET transmission rates form a sequence of OC-1 (51.84 Mbps), OC-3 (155 Mbps), OC-12 (622 Mbps), and OC-48 (2.5 Gbps). Because signals are synchronous, SONET can multiplex signals conveniently. SDH Synchronous Digital Hierarchy (SDH), defined by the CCITT (today s ITU-T) uses a SONET rate subset. As SDH adopts synchronous multiplexing and allows for flexible mapping, low-speed tributary signals can be added to or dropped from SDH signals without a large amount of multiplexing/demultiplexing devices. This reduces signal attenuation and investment in devices. SDH frame structure Low-speed tributary signals should distribute in a frame regularly and evenly for the convenience of adding them to or dropping them from high-speed signals. The ITU-T stipulates that STM-N frames adopt the structure of rectangle blocks in bytes, as shown in Figure 1-1: Figure 1-1 STM-N frame structure N ( in bytes) Regenerator section overhead AU-PTR Multiplex section overhead 9 N Payload 261 N STM-N is a rectangle-block frame structure of 9 rows x 270 x N columns, where the N in STM-N equals the N columns. N takes the value 1, 4, 16, and so on, indicating the number of STM-1 signals that form SDH signal. 1-1

3 The STM-N frame structure consists of three parts: the section overhead (SOH), which includes the regenerator section overhead (RSOH) and the multiplex section overhead (MSOH); the administration unit pointer (AU-PTR); and payload. AU-PTR is the pointer that indicates the location of the first byte of the payload in an STM-N frame so that the receiving end can correctly extract the payload. Multiplexing STM frames An STM-1 frame adopts the rectangular structure of 270 columns and 9 rows, with the first 10 columns as the overhead and the rest 260 columns as the payload. An STM-N frame is formed by interleaving N STM-1 frames. Figure 1-2 STM-1 frame structure SOH: The SDH section overhead. It is used for monitoring the entire STM-1 frame and does not carry user data. The SOH consists of the regenerator section overhead (RSOH) and the multiplex section overhead (MSOH). For example, B1 and B2 are used for bit error rate test (BERT) for the frame; A1 and A2 are frame synchronization bytes. AU-PTR: The administration unit pointer. It indicates the location of the payload in the STM-1 frame. POH: Path overhead. It is used for monitoring the payload. For example, the C2 byte in the POH indicates the payload type, and the G1 byte of the POH indicates whether a bit error is present in the payload. Payload: If channelization stops, the payload carries user data; if channelization continues, the payload carries the data of multiplexed lower-order channels. The following figure shows how four STM-1 frames are multiplexed into an STM-4 frame. In the same way, four STM-4 frames can be multiplexed into an STM-16 frame. 1-2

4 Figure 1-3 Process of multiplexing four STM-1 frames into an STM-4 frame D C Section overhead B Section AU overhead pointer A Section AU overhead pointer Section overhead AU Section pointer overhead P AU pointer Section overhead O Section overhead H Section overhead POH POH POH payload payload payload payload A B C D A B C D The recipient will demultiplex a received STM-4 frame into four STM-1 frames. During the multiplexing process, the A1, A2, j0, Z0, B1, E1, F1, D1, D2, and D3 fields in the RSOH of the first frame are multiplexed into the STM-4 frame while those of the rest three frames are treated as invalid. The other fields of each frame are multiplexed into the STM-4 frame separately. Figure 1-4 shows how an STM-16 frame in the SDH frame format is demultiplexed. Figure 1-4 The process of demultiplexing an STM-16 frame in the SDH frame format Rate hierarchy of SONET/SDH SDH frames at different rates are identified in the form of STM-N (N equals 1, 4, 16, 64, and so on, indicating that the frame is formed through multiplexing and interleaving N STM-1 frames). SONET frames at different rates are identified in the form of STS-N (N equals 1, 3, 12, 48, and so on, indicating that the frame is formed through multiplexing and interleaving N STS-1 frames. The following table lists the rate hierarchies of SONET and SDH. 1-3

5 Table 1-1 Rate hierarchy of SONET/SDH SONET SDH Rate STS Mbps STS-3 STM Mbps STS-12 STM Mbps STS-48 STM Mbps Overhead bytes SDH provides hierarchical monitoring and management functions. It provides section level monitoring and path level monitoring. Section level monitoring is subdivided into regenerator section level monitoring and multiplex section level monitoring, while the path level monitoring is subdivided into higher-order path level monitoring and lower-order path level monitoring. These monitoring functions are implemented using overhead bytes. SDH provides a variety of overhead bytes, but only those involved in E-CPOS configuration are discussed in this section. SOH The SOH consists of the RSOH and the MSOH. The regeneration section trace message J0 is included in the RSOH to send the section access point identifier repeatedly. Based on the identifier, the receiver can make sure that it is in continuous connection with the sender. This byte can be any character in the network of the same operator. If the networks of two operators are involved, the sending and receiving devices at network borders must use the same J0 byte. With the J0 byte, operators can detect and troubleshoot faults in advance or use less time to recover networks. POH The payload of an STM-N frame includes the path overhead (POH), which monitors low-speed tributary signals. While the SOH monitors the section layer, the POH monitors the path layer. The POH is divided into the higher-order path overhead and the lower-order path overhead. The higher-order path overhead monitors lower-level paths. Similar to the J0 byte, the higher-order VC-N path trace byte J1 is included in the higher-order path overhead to send the higher-order path access point identifier repeatedly. Based on the identifier, the receiving end of the path can make sure that it is in continuous connection with the specified sending end. The sender and the recipient must use the same J1 byte. In addition, the path signal label byte C2 is included in the higher-order path overhead to indicate the multiplexing structure of VC frames and the properties of payload such as whether the path is carrying services, what type of services are carried, and how they are mapped. The sender and the recipient must use the same C2 byte. 1-4

6 Terms Multiplex unit: A basic SDH multiplex unit includes containers (C-n), virtual containers (VC-n), tributary units (TU-n), tributary unit groups (TUG-n), administrative units (AU-n), and administrative unit groups (AUG-n), where n is the unit level sequence number. Container: Information structure unit that carries service signals at different rates. G.709 defines the criteria for five standard containers: C-11, C-12, C-2, C-3 and C-4. Virtual container (VC): Information structure unit supporting path level connection of SDH. It terminates an SDH path. VCs are divided into lower-order and higher-order VCs. VC-3 in AU-3 and VC-4 are higher-order VCs. Tributary unit (TU) and tributary unit group (TUG): TU is the information structure that provides adaptation between higher-order paths and lower-order paths. TUG is a set of one or more TUs whose locations are fixed in higher-order VC payload. Administrative unit (AU) and administrative unit group (AUG): AU is the information structure that provides adaptation between the higher-order path layer and the multiplex section layer. AUG is a set of one or more AUs whose locations are fixed in the STM-N payload. Optical carrier (OC): OC is a series of physical protocols (including OC-1, OC-2, and so on) defined for optical transmission over an SONET network. The number in an OC level corresponds to a rate for STS frames. The base rate is Mbps (OC-1), the rate of OC-3 is Mbps, and so on. E-CPOS The low-speed tributary signals multiplexed to form an SDH signal are called channels. A channelized POS (CPOS) interface makes full use of SDH to provide precise bandwidth division, reduce the number of low-speed physical interfaces on devices, enhance their distribution capacity, and improve the access capacity of dedicated lines. The basic functions of enhanced CPOS (E-CPOS) interfaces and CPOS interfaces are the same but their port rate hierarchies and channelization levels are different. For more information, refer to section Configuring the Operating Mode of an E-CPOS Interface/Channel. Channelized and unchannelized A channelized POS interface uses the low-speed tributary signals of STM-N to transmit multiple streams of data independent of one another over an optical fiber. Each data stream shares separate bandwidth and has its own start point, end point, and monitoring policy. They are called channels. An unchannelized POS interface uses all STM-N signals to transmit a stream of data over an optical fiber. The transmitted data has the same identifier, start point, and end point, and is regulated by the same monitoring policy. When multiple streams of low-speed signals are to be transmitted, channelization can make better use of bandwidth. When a single high-speed stream of data is to be transmitted, the unchannelized mode is recommended. Operating modes of E-CPOS interfaces An E-CPOS interface can operate in channelized mode or unchannelized mode: In channelized mode, a higher-order STM-N frame is regarded as being formed by four lower-order STM-N frames through time-division multiplexing. In this case, a higher-order STM-N frame will be demultiplexed into multiple lower-order STM-N frames for processing. In unchannelized mode, STM-N frames are processed without being demultiplexed. 1-5

7 Configuring an E-CPOS Interface Before transmitting data over SONET/SDH optical interfaces and using low-speed ports for accessing, configure the E-CPOS interface first. Complete the following tasks to configure an E-CPOS interface: Configuring an E-CPOS Interface Configuring the Operating Mode of an E-CPOS Interface/Channel Configuring an E-CPOS Interface Follow these steps to configure an E-CPOS interface: To do Use the command Remarks Enter system view system-view Configure the working mode of an interface card On a centralized device On a distributed device card-mode slot slot-number e-cpos card-mode slot slot-number subslot subslot-number e-cpos To make the newly configured working mode take effect, you need to restart the interface card. For more information about configuring the working mode of an interface card, refer to Device Management in the System Volume. Enter E-CPOS interface view controller e-cpos interface-number Set the framing format frame-format { sdh sonet } Configure the clocking mode clock { master slave } Configure the loopback mode loopback { local remote } SDH by default Slave clocking mode by default Disabled by default Configure the J0 byte Configure the signal degrade (SD) threshold and signal fail (SF) threshold Shut down the E-CPOS interface flag j0 { sdh j0-string sonet j0-value } threshold { sd sf } value shutdown The value ranges and the defaults for the arguments vary with devices. By default, the SD threshold is 10e-6 and the SF threshold is 10e-3. Up by default 1-6

8 If no cable is connected to a physical interface, shut down the interface with the shutdown command to avoid anomalies resulting from interference. As the shutdown command can disable an interface, use it with caution. Configuring the Operating Mode of an E-CPOS Interface/Channel As mentioned earlier, E-CPOS interfaces are different from CPOS interfaces in rate hierarchy and channelization hierarchy. Currently, the device supports STM-16 E-CPOS interfaces (at 2488 Mbps) and 622 Mbps/155 Mbps POS channels. Under each E-CPOS interface, you can create four 622 Mbps channels; under each 622 Mbps channel, you can create four 155 Mbps channels. You can use the using command to configure the operating mode of a channel. After you configure the operating mode of a channel as unchannelized, a POS interface of the corresponding rate will be created automatically. Follow these steps to create a 622 Mbps POS channel and configure its operating mode on a 2.5 Gbps E-CPOS interface: To do Use the command Remarks Enter system view system-view Enter E-CPOS interface view Create a 622 Mbps channel and enter its view Configure the 622 Mbps channel to operate in unchannelized mode controller e-cpos interface-number oc-12 oc-12-number using oc-12c Required Required The default is the channelized mode. Follow these steps to create a 155 Mbps POS channel and configure its operating mode on a 2.5 Gbps E-CPOS interface: To do Use the command Remarks Enter system view system-view Enter E-CPOS interface view controller e-cpos interface-number Create a 622 Mbps channel and enter its view Create a 155 Mbps channel and enter its view oc-12 oc-12-number oc-3 oc-3-number Configure the 155 Mbps channel to operate in unchannelized mode using oc-3 Required The default is the channelized mode. 1-7

9 Displaying and Maintaining E-CPOS Interfaces To do Use the command Remarks Display information about all channels of the specified E-CPOS interface Display information about the POS channels of the specified E-CPOS interface Clear the controller counter of the specified E-CPOS interface display controller e-cpos interface-number display interface pos interface-number reset counters controller e-cpos interface-number Available in any view Available in any view Available in user view E-CPOS Interface Configuration Example E-CPOS Interface Configuration Example Network requirements Configure a 2.5 Gbps E-CPOS interface to carry traffic via 155 Mbps POS channels, as shown in Figure 1-5. Figure 1-5 Network diagram for E-CPOS configuration Configuration procedure 1) Configuration on Router A # Configure the clock mode of interface E-CPOS 1/0. <RouterA> system-view [RouterA] controller e-cpos 1/0 [RouterA-E-Cpos1/0] clock master # Create a 155 Mbps POS interface on interface E-CPOS 1/0. [RouterA-E-Cpos1/0] oc-12 4 [RouterA-E-Cpos1/0-oc-12-4] oc-3 4 [RouterA-E-Cpos1/0-oc-12-4-oc-3-4] using oc-3c # Configure channelized interface POS1/0/4/4:0. [RouterA-E-Cpos1/0-oc-12-4-oc-3-4] interface pos 1/0/4/4:0 [RouterA-pos1/0/4/4:0] ip address ) Configuration on Router B # Create a 155 Mbps POS interface on interface E-CPOS 1/0. <RouterB> system-view [RouterB] controller e-cpos 1/0 [RouterB-E-Cpos1/0] oc-12 4 [RouterB-E-Cpos1/0-oc-12-4] oc-3 4 [RouterB-E-Cpos1/0-oc-12-4-oc-3-4] using oc-3c # Configure channelized interface POS1/0/4/4:0. [RouterB-E-Cpos1/0-oc-12-4-oc-3-4] interface pos 1/0/4/4:0 [RouterB-pos1/0/4/4:0] ip address After the connection is established, Router A can successfully ping Router B. 1-8

10 Troubleshooting E-CPOS Interfaces Symptom An E-CPOS interface is physically up, so are the channelized POS interfaces on it, but the link layer is down. Solution The physical parameter settings (such as clock source and scrambling) on the E-CPOS interface do not match those on the remote E-CPOS interface. The link layer protocol of the POS channel does match that of the remote POS channel. No IP address is configured for a local POS interface or its peer. The bandwidth of POS interfaces channelized from the local E-CPOS interface is not the same as that of POS interfaces channelized from the remote E-CPOS interface. POS interfaces channelized from the local E-CPOS interface are not the same as POS interfaces channelized from the remote E-CPOS interface in POS interface number. PPP authentication fails on the virtual POS interface. PPP authentication maybe fails due to incorrect PPP authentication parameters. You can use the display interface pos interface-number command to display the multiplexing path and PPP link negotiation information of the specified POS interface. An interface may be in one of the following four states: Pos1/0/1:0 current state: Administratively DOWN, Line protocol current state: DOWN, indicating that the interface is administratively shut down. Pos1/0/1:0 current state: DOWN, Line protocol current state: DOWN, indicating that the interface is not enabled or has not gone up on the physical layer. Pos1/0/1:0 current state: UP, Line protocol current state: UP, indicating that the interface has passed LCP negotiation. Pos1/0/1:0 current state: UP, Line protocol current state: DOWN, indicating that the interface has been activated but has not passed LCP negotiation. 1-9