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When an NE20E-S16 Is Interconnected to a Third-Party Device Through MP-group, an E1 Interface Is Physically Up But Experiences Protocol Down.

Publication Date:  2019-03-27 Views:  13 Downloads:  0
Issue Description

When an NE20E-S16 is interconnected to a third-party device through MP-group, an E1 interface is physical Up but experiences protocol Down.

[huawei]disp interf Serial0/2/0:0

Serial0/2/0:0 current state : UP (ifindex: 61)

Line protocol current state : DOWN 


Route Port,The Maximum Transmit Unit is 1500, Hold timer is 10(sec)

Derived from E1 0/2/0, Unframed mode, baudrate is 2048000 bps

Internet protocol processing : disabled

Link layer protocol is PPP 

LCP closed


Scramble disabled

Handling Process

1. Check that parameters, such as the CRC and framed mode, on both ends are consistent.

2. Establish a link loop and perform a test. The test result shows that devices on both ends can detect the loop and the link functions properly.

3. Check that the interfaces added by MP-group are also correct. It is suspected that PPP negotiation does not work properly. Run the debugging ppp all command. The command output includes the following error information:

Aug 29 2018 17:04:17.592 huawei %%01PPP/6/PPP_Debug(d):VS=Admin-VS-CID=0x807c04d2;PPP Dbg: PPP Error:

IfIndex<61>, Protocol<LCP>, FsmState<acksend>, ErrInfo:<[Mp] LcpUpCheck, Failed because The discri Not Same.>//The negotiation fails because the received identifier is inconsistent with that of the member interface.

Run the following command and check that the identifier of Serial 0/2/0:0 is 6296429530947087967:

[~huawei-diagnose]  disp inner-data ppp cid 807C04D2 info-type  pppnegoinfo 61 lcp his 

  VmePpp App Cid: 0x807c04d2


PPP LCP NegoInfo:

   uiIfIndex:          0x3d

   uiNeg_mru:          0x0

   uiNeg_asyncmap:     0x0

   uiNeg_upap:         0x0

   uiNeg_chap:         0x0

   uiNeg_magicnumber:  0x1

   uiNeg_pcompression: 0x0


   uiNeg_lqr:          0x0

   uiNeg_mrru:         0x1

   uiNeg_ssnhf:        0x0

   uiNeg_discr:        0x1

   uiNeg_callback:     0x0

   uiNeg_Auto:         0x0

   uiNeg_mschapv1:     0x0

   uiNeg_mschapv2:     0x0

   usMru:              0x0

   usMrru:             0x5dc

   uiAsyncMap:         0x0

   uiMagicNumber:      0x23a553af

   uiNumLoops:         0x0

   uiLqrPeriod:        0x0

   ucChapMdType:       0x0

   ucDiscrLen:         0x12

   ucDiscrClass:       0x1

   ucCallbackOpr:      0x0

   aucDiscrAddr:       6296429530947087967


   ucCallbackLen:      0x0

   ucMschapv1Mdtype:   0x0

   ucMschapv2Mdtype:   0x0

4. Check that the identifier sent by the third-party device is incorrect.

Root Cause

The identifier sent by the third-party device is incorrect.


1. Run the shutdown and then the undo shutdown commands on the two member interfaces of the MG-group interface to trigger re-negotiation.

2. Disable the terminal identifier negotiation function on devices at both ends. The configuration also takes effect after the shutdown and undo shutdown commands are run.

To disable identifier negotiation for NE devices, run the following commands:

<HUAWEI> system-view

[~HUAWEI] interface mp-group 1/0/1

[~HUAWEI-Mp-group1/0/1] undo discriminator


If the undo discriminator command is run on the MP-group interface, the shutdown command and then the undo shutdown command must be run on the sub-channels of the MP-group to make the preceding configuration take effect.