Cisco Systems OC-12/STM-14 manual Configuring DS3 Port BER Testing, DS3 Channel Loopback Mode

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Cisco IOS Software Configuration for the 1-Port Channelized OC-12/STM-4 (DS3) Line Card

How to Configure the 1-Port Channelized OC-12/STM-4 (DS3) Line Card

•Line—This loopback mode loops data from the receive path to the transmit path at the mux/demux part on the line card, returning all received data at the OC-12 level to the far end. In controller configuration mode, set the loopback mode to line, using the [no] loopback [internal line] configuration command:

Router(config-controller)# loopback line

Router(config-controller)#

Use the no form of this command to restore the default value to no loopback.

DS3 Channel Loopback Mode

The DS3 channel supports three loopback modes:

•Local—This loopback mode loops data from the transmit path to the receive path at the QJET location on the line card, allowing diagnostics to send data to itself over a single channel without relying on external connections. In serial interface configuration mode, set the loopback mode to local, using the [no] loopback [local network remote ] configuration command, as in the following example:

Router(config-if)# loopback local

Use the no form of this command to restore the default value, no loopback.

•Network—This loopback mode loops data from the STS1 receive path to the STS1 transmit path at the Mapper location on the line card, returning all received data over a single channel to the far end. In controller configuration mode, set the loopback mode to local, using the

[no] loopback [local network remote ] configuration command:

Router(config-if)# loopback network

Use the no form of this command to restore the default value, no loopback.

•Remote—This loopback mode sends an FEAC message over a single channel to the far end, requesting that it transition into network loopback mode. In controller configuration mode, set the loopback mode to local, using the [no] loopback [local network remote ] configuration command, as in the following example:

Router(config-if)# loopback remote

Use the no form of this command to restore the default value, no loopback.

Configuring DS3 Port BER Testing

You can set one local DS3 serial port to bit error rate test (BERT) mode while the remaining local serial ports continue to transmit and receive normal traffic. A BERT checks communication between the local and the remote DS3 ports. If traffic is not being transmitted or received, create a back-to-back loopback BER test and send out a predictable stream to ensure that you receive the same data that was transmitted. To determine if the remote DS3 serial port returns the BERT pattern unchanged, the system administrator for the remote router must manually set the remote DS3 serial port to loopback network line, while you enter a bert pattern interface configuration command at specified time intervals on the local DS3 serial port.

The following example shows the output from a back-to-back loopback BER test. The router types are a Cisco 12012 Router on the local (near) end, and a Cisco 12008 Router on the remote (far) end. Keepalive is disabled, while the loopback network line test runs between both routers. Clock source is

Cisco IOS Release 12.0(8)S

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Contents Contents Router# show controller oc12 1/0 Configuring the OC-12 ControllerRouterconfig# controller OC12 1/0 Router# configure terminalConfiguration Command Default Value Configuring the DS3 Serial InterfaceRouterconfig-if#ip address 10.1.2.3 Routerconfig# interface serial 1/01Router# copy running-config startup-config Cisco Remote Connection ManagementNo framing c-bit m13 No dsu modeCisco digital-link kentrox larscom No dsu bandwidth Kilobits/secSelecting a DSU Mode Verifying Local and Remote DS3 Port SettingsSetting the Sending and Receiving Rate Configuring the DSU Bandwidth RangeConfiguring Cyclic Redundancy Checks Using show Commands to Check System StatusConfiguring the Clock Source Enabling Payload ScramblingRouter# show controllers oc12 1/0 Show controllers oc12 slot/portShow controllers oc12 detail Show controllers oc12 slot/portchannel#Router# show controllers oc12 1/01 Ip subnet-zero Router# show running-configOC-12 Controller Loopback Mode Using Loopback CommandsLoopback modes Configuration Mode Command DS3 Channel Loopback Mode Configuring DS3 Port BER TestingNo loopback local network remote configuration command Bert Pattern To Invoke Command Checking Bit Errors Using a BertUsing show Commands to Verify Bert Configuration Entering Errors in BER TestsRouter# show controller oc12 1/01 bert Bert Bert Information ExplanationBert Information Explanation Routerconfig-if#ip address 1.1.5.1 Technical Assistance Related DocumentsRelated Topic Document Title Description Link

OC-12/STM-14 specifications

Cisco Systems OC-12/STM-14 is a high-performance networking solution designed to meet the demands of modern telecommunications and data transport applications. Operating at a data rate of 622 Mbps, the OC-12 (Optical Carrier level 12) and STM-14 (Synchronous Transport Module level 14), this technology provides a reliable and efficient method for organizations to transmit large volumes of data over fiber optic networks.

One of the key features of the OC-12/STM-14 system is its capability for high-speed data transfer. This makes it an ideal choice for service providers looking to deliver broadband services, video streaming, and other bandwidth-intensive applications. With support for multiple protocols, including SONET (Synchronous Optical Network) and SDH (Synchronous Digital Hierarchy), the OC-12/STM-14 can facilitate smooth communication and interoperability between various network devices.

Another significant characteristic of the OC-12/STM-14 is its scalability. Organizations can easily scale their networks by adding additional OC-12/STM-14 connections, accommodating their growing bandwidth needs without a complete overhaul of existing infrastructure. This flexibility is essential for businesses that expect fluctuations in data traffic or are anticipating future expansion.

Additionally, Cisco's OC-12/STM-14 employs advanced error correction and fault tolerance features, ensuring high reliability and minimal downtime. It supports sophisticated monitoring and network management capabilities, allowing administrators to proactively manage network performance and troubleshoot potential issues before they affect service quality.

Security is also a critical aspect of the OC-12/STM-14 architecture. Cisco incorporates robust security protocols to safeguard sensitive data during transmission, ensuring compliance with industry standards and protecting against unauthorized access.

In terms of compatibility, the Cisco OC-12/STM-14 integrates seamlessly with existing infrastructure and can work alongside various routing platforms. This compatibility significantly reduces the cost and complexity associated with upgrading legacy systems.

Ultimately, Cisco Systems OC-12/STM-14 offers a powerful solution for enterprises and service providers looking to enhance their networking capabilities. With its high-speed data transfer, scalability, reliability, and security features, it stands as a cornerstone technology in advanced telecommunications and data networking.
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