Description of the problem

This paper mainly introduces the typical scenarios and common positioning methods of 1+1 linear multiplexing segment. Focusing on typical case studies, it analyzes the operation reversal mechanism of the linear multiplexing segment protocol and the idea of analyzing problems in cross-product problems.

Linear multiplexing segment protection is a common protection method in SDH system, which conforms to ITU-T G.841 recommendation. At present, our company supports the main equipment of linear multiplexing segment protection, such as SDH/OSN/RTN/PTN/RNC/BSC/UMG, etc. 1 +1 linear multiplexing segment protection completes a series of protocol handshakes with the help of multiplexing segment K bytes in the overhead, and realizes the transformation of the four kinds of multiplexing segment states through the response of protocol controller to the various inversion conditions, so as to control the process of the service's joining and inversion. Thus, the protection of the service is realized.

Processing

Possible reasons for unsuccessful docking reversal:

1, MSP configuration is correct, whether the service is double sent to the LMSP work and protection single board;

2, whether the configuration of the MSP port state at both ends is the same (applicable to 1+1 double-end) whether the fiber connection is correct: work <-> work, protection protection;

3, there is no correct detection of K bytes and reported to the protocol; involves link status SF, SD, Normal there is no timely and correctly reported to the protocol;

4, whether the local/opposite-end single board has correctly responded to the k bytes sent by the opposite/local device within a specific time period

Root cause

No

Solution

Linear Multiplexed Segment Protection Inversion is used in point-to-point physical networks to provide multiplexed segment-level protection for services between two nodes. It can be dedicated protection, which means that a protection channel protects only one working channel, or shared protection, which means that a protection channel can provide protection to multiple working channels. Linear multiplexed segment protection does not protect against node failure. Usually, 1+1 protection is dedicated protection, while 1:N (including 1:1) is shared protection. 1+1 linear multiplexing segment protection inversion is divided into single-end and double-end methods, single-end method means that the working channel in a certain direction needs to be inverted, then only the working channel in the direction is inverted to the protection channel, while the other end maintains the state unchanged; double-end method will invert the working channels in both directions to the protection channel. The double-ended method inverts the working channel in both directions to the protection channel. According to whether it is restored or not, it can be categorized into restoration type and non-restoration type. The so-called recovery mode means that when the node is in the inverted state, the node releases the inversion and returns to the original normal state after the working section returns to normal, while the non-recovery mode means that when the node is in the inverted state, even if the working section returns to normal, the node will not act again, that is to say, the inverted state is maintained unchanged. Therefore, there are four types of 1+1 linear multiplexing segment protection inversion: 1+1 double-ended recovery type, 1+1 double-ended non-recovery type, 1+1 single-ended recovery type, 1+1 single-ended non-recovery type.

When double-end switching, the local end and the opposite end negotiate through K-byte interactive messages, and both ends switch at the same time; when single-end switching, the local end and the opposite end do not need to handshake, and there is no need for switching protocols. Therefore, it is generally recommended to configure it as single-ended switching mode. However, some devices only support double-ended mode in some scenarios, so when docking, first confirm the two sides can support the type of switching mode. (For example, BSC6900, when the backplane version of the plug frame where the POUc is located is A or B, if the board is configured with MTP2 link or AterOML link, it does not support MSP 1+1 single-ended inversion.)

Recommendation and Summary

Acquisition Data Requirements:

1. Docking schematic for testing

2. Simple steps and time points of the test, along with a record of the phenomena during the test.

3. Alarm messages, abnormal event reports and operation log records

This chapter related technical information and SDH equipment troubleshooting process is collected and organized by Shenzhen Optical Transmission Network Technology Company Limited (www.opticaltrans.com), reproduced please retain! Our company specializes in the sales of Huawei SDH optical transmission equipment,SDH transmission equipment.