Router mistake result in the unable communication among the MA5200 of the PPPoE users

Publication Date:  2012-09-13 Views:  249 Downloads:  0
Issue Description
Three equipments of company build up a network triangular, each router connect the user of S8016-MA5200-MA5100-PPPoE.
Now the case is the user from MA5200(1)can’t visit the server from MA5200(2),but the user from MA5200(3)can.
Alarm Information
NONE
Handling Process
1 The equipment at the super layer of MA5200(1)s8016 and the router of company C can both ping the server normally. But from MA5200(1),ping the server is failed
2 Ping MA5200(1)to MA5200(2)works, tracert from the user under MA5200(1) to the server, found that the next hot can only reach the gateway of MA5200(1). Tracert from MA5200(1)to the server, display the message that “the router isn’t able to arrive” so the problem is on the router of MA5200(1).
3 Check the routing table of MA5200(1)by display ip route, find out that it exist un router information en detailed to the net of server and the interface corresponded in MA5200(1)is vt17. Check the configuration, found that the gateway address mask is too short, covered the ip address which should be the ip address under MA5200(2).  So the message following the router direct (this direct router don’t have the destination ip address, is a black hole router in fact) instead of the default router which pointing to the up-load interface. So ping the server don’t works.
4 Delete the VT, so the user can visit the server under MA5200(2)normally.
Root Cause
That because the gateway address mask is too small, covered the ip address which should be the ip address under MA5200(1). So the message following the router direct (this direct router don’t have the destination ip address , is a black hole router in fact) instead of the default router which pointing to the up-load interface. So ping the server don’t works. 
Suggestions
NONE

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