I have the following topology:
IOU3 is the ABR, and is summarizing Area 0 prefixes as a summary route 2000::/16 into Area 1.
IOS version: 15.5.
RFC1583 is ENABLED on IOU3 (and everywhere else), which means that the cost of the summary route should be based on the specific subnet with the LOWEST cost, and from IOU3's perspective that would be a cost of 1 out its e0/1 interface to 2000:2323::/64.
But strangely enough, IOU3 is advertising the summary route with the HIGHEST cost, namely: 3 (cost of the 2000:1111-prefixes). That is strange, because RFC1583 is enabled.
IOU3's config:
IOU3#sh run | s router ospf router ospfv3 1 router-id 3.3.3.3 ! address-family ipv6 unicast area 0 range 2000::/16 exit-address-family
IOU3#sh ospfv3
OSPFv3 1 address-family ipv6
Router ID 3.3.3.3
...
Reference bandwidth unit is 100 mbps
RFC1583 compatibility enabled
Area BACKBONE(0)
IOU3's routing table:
IOU3#sh ipv6 route
IPv6 Routing Table - default - 9 entries
...
O 2000::/16 [110/3]
via Null0, directly connected
O 2000:1111:1::/64 [110/3]
via FE80::A8BB:CCFF:FE00:700, Ethernet0/1
O 2000:1111:2::/64 [110/3]
via FE80::A8BB:CCFF:FE00:700, Ethernet0/1
O 2000:1212::/64 [110/2]
via FE80::A8BB:CCFF:FE00:700, Ethernet0/1
C 2000:2323::/64 [0/0]
via Ethernet0/1, directly connected
L 2000:2323::3/128 [0/0]
via Ethernet0/1, receive
C 2001:3434::/64 [0/0]
via Ethernet0/0, directly connected
L 2001:3434::3/128 [0/0]
via Ethernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
IOU3 is advertising the summary route to IOU4 in Area 1 with a cost of 3:
IOU4#sh ospfv3 database inter-area prefix
OSPFv3 1 address-family ipv6 (router-id 4.4.4.4)
Inter Area Prefix Link States (Area 1)
LS age: 1675
LS Type: Inter Area Prefix Links
Link State ID: 0
Advertising Router: 3.3.3.3
LS Seq Number: 80000001
Checksum: 0x39C2
Length: 32
Metric: 3
Prefix Address: 2000::
Prefix Length: 16, Options: NoneI don't understand why IOU3 is advertising the summary route with a cost of 3? RFC1583 is enabled, so it should be a cost of 1..?
