NE80 and GSRXX4XX, NE5000E establish OSPF relation. GSRXX0XX and CXXXX are connected through static route. GSRXX0XX need upgrade to GSRXX4XX and parts of service is cutover NE5000E, including CXXXX device. Connect GSRXX0XX device with CXXXX device. Shutdown it and cut CXXXX over NE5000E. Static route is configured on NE5000E and it can communicate with CXXXX. After the cutover is finished, NE80 cannot access CXXXX attached service.
CXXXX attached address can be pinged on NE5000E. CXXXX address cannot be pinged on NE80. Check routing table on NE80 and the route from NE80 to CXXXX points to GSRXX0XX. Enter dislay ospf lsdb ase 10.0.0.0 NE80.
Besides NE5000E distributes LSA, GSRXX0XX_A also distributes LSA. Enter show ip cef 10.0.0.0 on GSRXX0XX_A and next-hop points to GSRXX0XX_B. Check static route configuration (ip route 10.0.0.0 255.255.255.0 126.96.36.199) on GSRXX0XX and next-hop is 188.8.131.52. Enter show ip route 184.108.40.206 on GSRXX0XXand the route to 220.127.116.11 matches the route of next-hop 18.104.22.168/16 advertised by GSRXX0XX_B. The route is not valid. When the router is forwarded, it is longest match. The direct interface of static route is down, but the next-hop of route iteration is valid. NE80 can reach destination through GSRXX0XX_A. When data traffic is forwarded to GSRXX0XX_A, there is route blackhole. On GSRXX0XX_A delete the route to CXXXX. NE80 computes accurate route to NE5000E and the service recovers.
1. NE80 does not learn route on CXXXX.
2. NE5000E route is problematic.
3. OSPF appendix E is problematic.
4. NE80 learns the route wrongly.