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Knowledge Base

EPL service is down due to frame out of phase

Publication Date:  2012-07-25  |   Views:  230  |   Downloads:  1  |   Author:  qiuyuanhui  |   Document ID:  EKB0000563225


Issue Description

Customer want to creat a EPL service between the OSN 3500 EFS0 Board and the OSN 7500 EFS4 Board,
the topo is described in the picture. in the picture. PDH network is two hop of other vendor's microwave using E1.
bandwigth of SDH network is STM-1 .only one vc12 is bound to the vctrunk both FE sides.the service is down when it is created.
the vesion of osn 3500 and 7500 is V100R008C02

Alarm Information

OSN 3500 and OSN 7500 reported :ALM_GFP_dLFD and VCAT_LOM_VC12

Handling Process

1. By checking the service configuration of the bound channels, we find the timeslots bound
at the two ends are consistent without any problem, and the ports are configured normally.
2. The EFP0 is used to transmit Ethernet frames locally over the existing PDH telecommunications networks, meeting the requirements of Ethernet service convergence. EFS0 don't support this scenario. so replace EFS0 and EFS4 with EFP0, then the service is finnally up.

Root Cause

1.The ALM_GFP_dLFD alarm indicates a GFP OOF hat occurs on a VCTRUNK. If the ALM_GFP_dLFD alarm is generated,the Ethernet traffic over the VCTRUNK is unavailable.
2.VCAT_LOM_VC12indicating the loss of the virtual concatenation multiframe in the VC12 path. This alarm occurs
when the system detects that the multiframe indicator (MFI) field in the K4 byte of the VC-12 timeslot is illegal.”
3 EFS0 and EFS4 is EOS board,It need the synchronized network. but the network cantain a hop of PDH microwave, It might cause the frame out of phase.


EFP0 is a EoPDH board ,Use EFP0 instead of EFS0 to transfer EPL through PDH and SDH mixed network.