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OSPF Routing Bit in LSA

yuening liao
Beginner
Beginner

Hello Everyone,

111.png

the interface f0/0 of R1 and f0/1 of R3 were assigned to vrf vpn13. after all ospf sessions were established i found that R1 could recieve the inter area routes from another area well, but r3 couldn't. the show ospf database command presents that the all LSAs in OSPF DATABASE of R1 were set with Routing Bit, although the inter-area LSA in R3 were not. all the LSA without Routing Bit couldn't be put into routing table of r3. Under which circumstance the Routing Bit should be set on LSA? Is the Routing Bit not set on the LSA which should be sent toward a vrf interface locating in a None-Zero Area?

besides i'm also aware that r3 recieved a route from r2, however it's not present in r3's ospf database

R3#sh ip os da

            OSPF Router with ID (3.3.3.3) (Process ID 13)

                Router Link States (Area 1)

Link ID         ADV Router      Age         Seq#       Checksum Link count

2.2.2.2         2.2.2.2         310         0x80000003 0x001268 2

3.3.3.3         3.3.3.3         309         0x80000003 0x005766 2

                Net Link States (Area 1)

Link ID         ADV Router      Age         Seq#       Checksum

23.0.0.3        3.3.3.3         309         0x80000001 0x00C53A

                Summary Net Link States (Area 1)

Link ID         ADV Router      Age         Seq#       Checksum

1.1.1.1         2.2.2.2         306         0x80000001 0x008D98

2.2.2.2         2.2.2.2         506         0x80000001 0x00FA31

12.0.0.0        2.2.2.2         345         0x80000001 0x00150A

R3#sh ip ro vrf vpn13 22.22.22.22

Routing entry for 22.22.22.22/32

  Known via "ospf 13", distance 110, metric 11, type intra area

  Last update from 23.0.0.2 on FastEthernet0/1, 00:06:12 ago

  Routing Descriptor Blocks:

  * 23.0.0.2, from 2.2.2.2, 00:06:12 ago, via FastEthernet0/1

      Route metric is 11, traffic share count is 1

R3#

thank you very much for your help in advance.

7 Replies 7

Peter Paluch
Cisco Employee
Cisco Employee