For topology, see the attachment. Each equipment is configured as follows:
1. Configure the ROUTER ID of SUT1 to $SUT1_ROUTERID, that of SUT2 to $SUT2_ROUTERID, and set $SUT1_ROUTERID<$SUT2_ROUTERID.
2.SUT1/SUT2/RT1 run OSPF, and they are in area 0.
3.SUT1/RT5/SUT2 run OSPF, and they are area 1 of NSSA.
4.SUT1/RT3 run OSPF, and they are in area 2.
5.Configure RT5 with static route of 126.96.36.199/24, and refer it to OSPF; show LSDB on RT3, with the output as:LSDB of RT3 contains type5 LSA of the route 188.8.131.52/24, and the router id is $SUT2_ROUTERID.
The following symptoms occur:
1)SUT2 generates LSA3 in area1 that is advertised to RT3\SUT1.
2)LSA4 generated in area2 points to the LSID SUT2.
3)area0 cannot generate two LSA4 pointing to RT5.
The handing process for the above symptoms include:
1.As NSSA, area1 in this topology is unique, and connected to area2 through SUT2. \SUT1; RT5 could reach area2 via two paths, and SUT2 belongs to area1. So SUT2 will generate LSA3 that is to be advertised to RT3\SUT1. This differs to the strict definition of LSA3 generated by ABR between areas;
2. For LSA4 defined in RFC, its LSID should be IP address of ASBR. In this topology, we could regard SUT2 as ASBR, because it is SUT2 that performs conversion between LSA7\LSA5.
3.SUT2 functions as ABR to convert LSA7\LSA5, so it cannot generate two LSA4 in area0.