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OMG Interface of the UMG Cannot Successfully Ping the Address of VLANIF Gateway on the NE40

Publication Date:  2012-07-27 Views:  33 Downloads:  0
Issue Description
 Network topology:
UMG-----NE40 (signaling); UMG-----S3000-----NE40 (maintenance)
Networking description:
The UMG is connected to the NE40 in single point mode. The MIR interface on the UMG is directly connected to the NE40 for signaling; the OMC interface on the UMG is connected to the NE40 through a Layer 2 switch for maintenance. The two interfaces belong to different VLANs. VLANIF is enabled and functions as the gateway for the maintenance and signaling of the UMG.
Symptom:
The gateway (the IP address of the VLANIF gateway on the NE40) cannot be successfully pinged from the OMC interface of the UMG. Other IP addresses except that of the gateway in the same VLAN can be successfully pinged from the OMC interface. The IP address of the OMC interface can be successfully pinged from the NE40. The MIR interface for signaling is normal.
Version of the NE40: NE40NE80-V300R002C01B533 
 
Alarm Information
Null
Handling Process
1. Use a test cable to replace the cable used to connect the NE40 and the S3000. The problem cannot be solved.
2. Check the configurations of the S3000. The S3000 uses the default configuration. The OMC interfaces (on the UMG) that connect the UMG and the NE40 belong to the default VLAN vlan1. Negotiation between the interfaces is normal.
3. Directly connect the OMC interface of the UMG to the NE40. The problem persists.
4. Analyze the UMG configurations. The OMC interface and the MIR interface learn the same MAC address of the gateway. The OMC interface and MIR interface are located in the same LSW chip built in the NET card. When the two interfaces on an LSW chip alternately learn the same gateway MAC address, signaling packets and maintenance packets may be sent to wrong interfaces. The signaling packets are much more than the maintenance packets, and many maintenance packets may be forwarded to the MIR interface. At this time, the NE40 cannot be pinged through.
5. Check the NE40. The MAC addresses of VLANIF for different VLANs are the same.
6. When the UMG receives an ICMP request message and sends out the reply message within a very short time, the MAC address is still mapped to the IP address of the OMC. That is why you can successfully ping the OMC interface on the UMG from the NE40.
7. Solutions:
(1) Configure the UMG to forward signaling packets through the MPU rather than the MIR interface of the NET card.
(2) Configure the maintenance gateway for the UMG on another device. Thus the gateway MAC address learned by the MIR interface will be different from that learned by the OMC interface.
You can use either solution to solve the problem. 
 
Root Cause
1. The cables used to connect the NE40 with the S3000 may be abnormal.
2. Configurations of the S3000 may be incorrect.
3. The rate and negotiation between the interfaces of the S3000 and the Ne40 may be abnormal.
4. The UMG may fail to learn the MAC address of the VLANIF gateway on the NE40. 
 
Suggestions
1. The MAC addresses of VLANIF of different VLANs on the NE40 are the same.
2. When you connect your device to a core network device, understand basic knowledge of the core network and contact the core network personnel for the problems you encounter. 
 

END