OSN3500 SSN1EFS0A (16-channel FE Ethernet Switching Processing Board) single board is an Ethernet switching processing board, which is mainly used to solve the telecommunication application areas such as Ethernet service access, bandwidth management, and Layer 2 switching of Ethernet services. The board supports Layer 2 switching, MPLS, multicast and other functions and features. The board supports 1:1 TPS (Tributary Protection Switching) protection. Typical networking application of Ethernet switching processing board is shown in Figure 1, which can realize Ethernet access, aggregation, Layer 2 switching of Ethernet data, port isolation, flow classification, data flow control, VLAN management, priority configuration and other data features, as well as data encapsulation/decapsulation, virtual cascade, SDH mapping/demapping and other functions. At the same time, it can be docked with broadband access equipment and digital communication equipment to provide a network-wide solution.

Problem Description

OSN3500 network A to B site has two different routes of the link, the two stations use N1EFS0A single board to open point-to-point services, a total of 8 VC12 bandwidth, 1-4 VC12 and the latter 5-8 VC12 to go to a different route, in one side of the route interruptions, the Ethernet is not interrupted, in the configuration of the first 4 VC12, the business is normal, will be added to the 5-8 VC12 binding, the EFS0 single board reported ETH_LOS alarms, need to identify the cause of this. EFS0 board reports ETH_LOS alarm, need to investigate the cause.

Alarm message

ETH_LOS

Processing

1, configure 1-4 VC12, business is normal, there is no ETH_LOS alarm, ruled out the external port and switch port rate mismatch, network port and network port failure, due to the addition of 5-8 VC12 reported ETH_LOS, suspect that there is anomalies in the 5-8 VC12, will be 1-4 VC12 to bind, will be 5-8 VC12 binding to the VCTRUNK1, business is also normal, there is no ETH_LOS alarm, ruled out the existence of abnormal 5-8 VC12, and then the 1-8 VC12 there are abnormalities, and then the 1-8 VC12 binding to the VCTRUNK1, the service is normal, there is no ETH_LOS alarm, exclude the existence of abnormalities in 5-8VC12, and then 1-8VC12 are bound at the same time, ETH_LOS generated, the service does not work, at this time and the switch side to confirm that the switch side port physical down, the reason is that spanning tree detects a loop will be the port physical down.

2. Check the SDH service side, the path is normal and there is no loop.

3, check the Ethernet service configuration of the two stations, both stations are configured for Ethernet LAN services, 1-4 VC12 binding VCTRUNK1, 5-8 VC12 binding VCTRUNK2, the external port using PORT1, are added to the same VB of the same VLAN at the same time, the use of the 802.1q protocol, the 801q protocol based on the VLAN + MAC Learning and forwarding, in the case of receiving broadcast frames or unicast unknown frames from the customer side, it will broadcast the data to all other interfaces in the same VLAN except the incoming interface of the message, so the broadcast frames will cycle back and forth between the two stations, resulting in loops, and the switch side starts the Spanning Tree (MSTP) protocol, which detects the loops and turns the ports down, so the transmission side ETH_LOS alarm is reported.

4, according to business requirements, in the case of a link failure, half of the time slot is not available, the Ethernet can not be interrupted, this requirement can be realized using the LCAS function, the two stations of the 1-8VC12 are bound to the VCTRUNK1, select the Ethernet single board - Ethernet Configuration - Ethernet Interface Management: in the internal port of the LCAS tab, the LCAS function will be LCAS enabled VCTRUNK1, Ethernet is normal, the transmission side reported ETH_LOS alarms. The Ethernet is normal and the ETH_LOS alarm disappears.

Failure Cause

The Ethernet LAN service is configured on the transmission side, and two VCTRUNKs are added to the same VLAN of the same VB between two stations, resulting in a loop on the transmission side, and MSTP Spanning Tree is enabled on the switch side by default, and Spanning Tree detects the loop and turns the ports down, which results in an ETH_LOS alarm on the transmission side.

Solution

Bind 1-8VC12 to the same VCTRUNK, and enable LCAS function, so that the Ethernet service will not be affected in case of partial time slot failure.

Suggestion and Summary

1, LCAS function can dynamically adjust the bandwidth, you can use this function to protect different routes.

2、Switching side default MSTP function is on, and the default configuration, BPDU message without VLAN, in the VLAN division configuration, MSTP protocol BPDU message with VLAN.

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