The devices are NE5000E (version: V200R001B02JSP06) and NE80E(version: V100R002B02JSP06). The topology can be referred to the attachment.
Cutover VIP and observe interface traffic. INPUT traffic and OUTPUT traffic are little and user cannot access external network.
Check the route of VIP network segment on C12406-1 and there is one static route pointing to C12406-2 on C12406-1. Through the check the route is added to guide parts of VIP traffic to return MAN from C12406-2. Delete static route of VIP on C12406 and the service recovers.
1. Tracert this VIP from external network and it cannot reach within MAN.
2. The route of VIP in old network is through static－－>OSPF－－>BGP.
3. Check the roundtrip of VIP through C12406-1 static－－>C12406-2－－>NE40.
4. Analzye new network and this VIP is not in OSPF (route policy filters it), advertise VIP network segment on NE80E through BGP. NE5000E can learn VIP network segment through BGP.
Before cutover notice route trend and after cutover adjust route of previous network.