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About Failure of One Static Route from Private Network Under NE80

Publication Date:  2012-07-27 Views:  56 Downloads:  0
Issue Description
Version: VRP 3.10-0426
Topology: PC(ce1)--E3/0/7--ne80(pe)--E3/0/11--AR46(ce2)---Server(10.1.3.75)
Symptom Description: PC(ce1) is in vpn1, and AR46(ce2) in vpn2. Add one network segment pointing to server in both vpn 1 and 2, and the next hop is the static route of AR46(ce2). However, PC cannot communicate with Server. 
Alarm Information
Null
Handling Process
Add the egress interface parameters to the configuration for static route of private network in vpn1, as follows: 
ip route-static vpn-instance vpn1 10.1.0.0 255.255.0.0 Ethernet 3/0/11 132.108.47.162
Once the parameters are added, FIB entries of interface board show that egress interface is correct; perform another test, and communication is restored. The correct FIB entries are as follows: 
[NE80-diag]disp efu fib 3 10.1.0.0 16 vpn1                       
 Start display lpu fib on board 03...     
 Message sending success.                                                                                    
[NE80-diag]                                                              
 IP address              = 10.1.0.0                                             
 IP prefixLength         = 16                                                   
 VRF index               = 6                                                    
 Signature               = 0                                                    
 ecmpThr1                = 100                                                  
 ecmpThr2                = 0                                                    
          nextHop[0] ipaddr = 132.108.47.162                                    
          tegressContext = 0                                                    
          tb = 13 tp = 0xc subIndex = 0 
Root Cause
1. NE80 could ping to both server and PC, and the communication is normal. 
2. Check the routing table of private network at NE80, and it is found that NE80 could learn the relevant direct and static route correctly. 
3. In this case, NE80 will forward packets according to the FIB of interface board, so analyze the FIB entries advertised to interface board by NE80. 
4. According to FIB on vpn1 on NE80, the egress interface is not the actual next hop in FIB: 
[NE80-diag]disp efu fib 3 10.1.0.0 16 vpn1                      
 Start display lpu fib on board 03...                                           
 Message sending success.                                                       
 [NE80-diag]                                                              
 IP address              = 10.1.0.0                                             
 IP prefixLength         = 16                                                   
 VRF index               = 6                                                    
 Signature               = 0                                                    
 ecmpThr1                = 100                                                  
 ecmpThr2                = 0                                                    
          nextHop[0] ipaddr = 132.108.47.162                                    
          tegressContext = 0                                                    
          tb = 13 tp = 0x7 subIndex = 0  
Where, port number tp=0x7 (represents for that port number is 10, and non-0xc-- the correct port number is 11). This indicates that error occurs to the static route when it is advertised to the interface board; that is, the egress interface (E3/0/10) is not the same as that E3/0/11 in routing table.
Suggestions
It is suggested to add the parameter of egress interface for static route from private network, avoiding such a problem alike. 

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