OSPF calculated metrics are slightly different between ospf anf ospfv3, same links, same costs. NSSA

OSPF 3 appears to get metrics incorrect in a NSSA

Correct me if I’m wrong but if the routes are injected in the same place, traverse the same links with the same metrics should the totals cost be identical ?

Rip ---- SRX3a ---ospf area 10 (nssa)----R4—ospf area(0)---R2

sample ripng route
fd17:f0f4:f691:f:9::1

sample rip route
172.31.0.0/24

SRX3a

policy-statement >OSPF {
    term 10 {
        from protocol rip;
        then {
            external {
                type 1;
            }
            accept;
        }
    }
    term 20 {
        from protocol ripng;
        then {
            external {
                type 1;
            }
            accept;
        }
    }
}

So far so good

[edit routing-instances SRX3a protocols]
root@SRX3# run show route fd17:f0f4:f691:f:9::/80                    
SRX3a.inet6.0: 33 destinations, 36 routes (33 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
fd17:f0f4:f691:f:9::/80
                   *[RIPng/100] 08:30:41, metric 3, tag 0> to fe80::56e0:3200:51d7:68c4 via fe-0/0/5.81
[edit routing-instances SRX3a protocols]
root@SRX3# run show route 172.31.0.1                                 
SRX3a.inet.0: 28 destinations, 28 routes (28 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
172.31.0.0/24      *[RIP/100] 08:31:00, metric 3, tag 0> to 172.30.81.2 via fe-0/0/5.81
[edit routing-instances SRX3a protocols]
root@SRX4# run show route fd17:f0f4:f691:f:9::1
inet6.0: 46 destinations, 54 routes (46 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
fd17:f0f4:f691:f:9::/80
                   *[OSPF3/150] 00:00:49, metric 4, tag 0> to fe80::de38:e100:257c:9fc5 via fe-0/0/4.37
[edit protocols]
root@SRX4# run show route 172.31.0.0              
inet.0: 42 destinations, 44 routes (42 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
172.31.0.0/24      *[OSPF/150] 00:01:42, metric 4, tag 0> to 172.30.37.5 via fe-0/0/4.37
[edit protocols]
root@SRX4#
root@EX2# run show route 172.31.0.0   
inet.0: 40 destinations, 40 routes (40 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
172.31.0.0/24      *[OSPF/150] 00:01:02, metric 5, tag 0> to 172.30.0.82 via ge-0/0/14.64
[edit]
root@EX2# run show route fd17:f0f4:f691:f:9::1   
inet6.0: 42 destinations, 47 routes (42 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
fd17:f0f4:f691:f:9::/80
                   *[OSPF3/150] 00:01:04, metric 4, tag 0> to fe80::2ac0:da00:40d9:c284 via ge-0/0/14.64

Look above the metrics are different in area 0

Now if I switch area 10 to be a normal area and not a  NSSA metrics are identical again. 

root@EX2# run show route 172.31.0.1   
inet.0: 40 destinations, 40 routes (40 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
172.31.0.0/24      *[OSPF/150] 00:02:53, metric 5, tag 0> to 172.30.0.82 via ge-0/0/14.64
[edit]
root@EX2# run show route fd17:f0f4:f691:f:9::1   
inet6.0: 42 destinations, 47 routes (42 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
fd17:f0f4:f691:f:9::/80
                   *[OSPF3/150] 00:02:55, metric 5, tag 0> to fe80::2ac0:da00:40d9:c284 via ge-0/0/14.64
[edit]

does anyone have any reason for the differance, should OSPFv3 and OSPF not be identical in this respect ?