Null route issue

Publication Date:  2014-11-24 Views:  528 Downloads:  0
Issue Description
Current S5700 is connected to NE40E, with a dedicated line connected to other site private network. One day, customer finds that the bandwidth usage between the interface of S5700 and NE40E increases to over 1 GB. Below is current configuration:

Int vlan 2
Ip address – vlan connected with NE40E

Int vlan 3
Ip address – vlan connected with dediated line

Int gi 0/0/1
Port link-type access
Port type default vlan 2

Int gi 0/0/2
Port link-type access
Port type default vlan 3

Ip route-static – connected with NE40E
Ip route-static – connected with dedicated line

Int gi 8/0/1
Ip address

Ip route-static – connected with S5700

Handling Process
Through troubleshooting the issue, we find that the dedicated line is disconnected with S5700 due to other technical maintenance. Tracroute result shows that if if wants to access to, the traffic will then go to NE40E. But the next hop of in NE40E is S5700, so there is loop causing high traffic between the equipment.
As the disconnection time is about 3hours and we can’t plug in the dedicated line cable back to S5700, Null0 route is temporarily created to solve the problem.

Undo Ip route-static
Ip route-static Null0