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NE80 Fails to Interconnect with the 12000 Router of Supplier C Through POS Interfaces

Publication Date:  2012-07-27 Views:  44 Downloads:  0
Issue Description
 Networking diagram: S8505----NE80----12000 router made by supplier C Fault symptom: After a user logs in to the NE80, the GE interface and 155M interface are both normal whereas the 2.5G POS interface cannot go Up. The POS modules and boards at both ends work normally, but the 2.5G POS interface cannot go Up. 

 
Alarm Information

 Null 

 

Handling Process
 The default configurations of the POS interfaces on the Huawei NE40/NE80 are different from those on the 12000 router made by supplier C, such as the link layer encapsulation mode, CRC, and link scrambling. Therefore, you need to check each item to ensure configuration consistency.
1. Link layer encapsulation mode: The default link layer protocol of the 12000 router is HDLC whereas the default link layer protocol on the NE80 is PPP. View the configurations of the two devices, and you can find that the link-protocol hdlc command is used on the NE80 and the link layer encapsulation mode on the NE80 is changed to HDLC. Therefore, the possibility of inconsistency in link layer encapsulation modes can be excluded.
2. CRC: By default, the 12000 router adopts 16-bit CRC whereas the NE80 adopts 32-bit CRC. In addition, the CRC on the NE80 cannot be changed. Therefore, the CRC on the 12000 router needs to be changed to 32-bit CRC. View the configuration on the 12000 router, and you can find that the crc 32 command is used to change the CRC mode to 32 bits. Therefore, the possibility of inconsistency in CRC can be excluded.
3. POS link scrambling: By default, the scramble function is disabled on the 12000 router but is enabled on the NE80. View the configurations on the two devices, and you can find that the undo scramble command is used on the NE80 to disable the scramble function. Therefore, the possibility of inconsistency in the scramble function can be excluded.
4. Physical layer encapsulation mode of POS interfaces: By default, the physical layer encapsulation mode of the POS interfaces on the 12000 router is SONET whereas the physical layer encapsulation mode of the POS interfaces on the NE80 is SDH. The two modes are compatible to each other and do not affect the interface status or data forwarding, but you are recommended to set the same physical layer encapsulation mode for the POS interfaces on the NE80 and the 12000 router. The fault persists after the physical layer encapsulation mode of the POS interfaces on the NE80 is changed to SONET. Therefore, the possibility of inconsistency in physical layer encapsulation modes can be excluded.
5. Check the system logs and you can find the following alarms:
SRM/1/LabelMismatch:OID=1.3.6.1.4.1.2011.2.17.0.145,Index=67109638,SlotNum=7,SubCardNum=0,PortNum=0, receive path signal label mismatch!
Run the dis inter pos 7/0/0 ver command to view details about POS 7/0/0 on the NE80.
SDH overhead:(Rx/Tx)
F1 : NA/NA , J0 : 0x48/0x4e, K1 : 0x00/0x00, K2 : 0x00/0x00
S1 : 0x0f/0x08, C2 : 207/0x16, F2 : NA/NA , Z3 : NA/NA You can find that the C2 value of the NE80 is different from the C2 value (207) of the 12000 router. As a result, the problem occurs. Run the flag c2 207 command on the POS interface of the NE80 to synchronize the C2 value of the NE80 with that of the 12000 router. Then, the fault is rectified.
interface Pos7/0/0
undo shutdown
link-protocol hdlc
flag c2 207
undo scramble
ip address 19.9.x.x 255.255.255.252 

 
Root Cause
 1. The link layer encapsulation modes of the two devices are different. 2. The CRC of the two devices are different. 3. The POS link on one device is scrambled whereas the POS link on the other device is not scrambled. 4. The physical layer encapsulation modes for the POS interfaces on the two devices are different. 

 
Suggestions
 For low-rate POS interfaces such as 155M POS interfaces, the NE40/80 does not detect the C2 value. Thus, if the C2 values on both ends are different, the interfaces can still go Up. For high-rate POS interfaces such as 2.5 G POS interfaces, the NE40/80 detects whether the C2 values on both ends are the same. Inconsistency in C2 values causes the POS interfaces to go down. In this case, you must synchronize the different C2 values on high-rate POS interfaces. 

 

END