12-17-2011 01:02 PM - edited 03-07-2019 03:56 AM
Hi all,
I have one question about knowing which database is for Area 0 and Area 2.
Below is output
3550SMIB# sh ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 3 (DNA) 0x80000005 0x00ADF9 1
2.2.2.2 2.2.2.2 121 0x800003E1 0x007A4F 2
3.3.3.3 3.3.3.3 1303 0x800001BC 0x002641 3
4.4.4.4 4.4.4.4 2022 0x80000189 0x00BAF4 2
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
192.168.5.3 4.4.4.4 2022 0x8000017F 0x0039E4
192.168.6.3 4.4.4.4 2022 0x800003AA 0x009F54
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.10.0.0 3.3.3.3 1303 0x80000019 0x0009FC
10.10.0.1 1.1.1.1 8 (DNA) 0x80000001 0x0070B2
10.10.1.1 1.1.1.1 8 (DNA) 0x80000001 0x0065BC
10.10.2.1 1.1.1.1 8 (DNA) 0x80000001 0x005AC6
10.10.3.1 1.1.1.1 8 (DNA) 0x80000001 0x004FD0
10.20.0.1 2.2.2.2 1897 0x80000018 0x00B547
10.20.1.1 2.2.2.2 1897 0x80000018 0x00AA51
10.20.2.1 2.2.2.2 1897 0x80000018 0x009F5B
10.20.3.1 2.2.2.2 1897 0x80000018 0x009465
10.20.4.0 1.1.1.1 3 (DNA) 0x80000001 0x00587D
192.168.3.2 2.2.2.2 882 0x80000136 0x00FC93
192.168.4.2 1.1.1.1 8 (DNA) 0x80000001 0x007D4C
192.168.4.2 3.3.3.3 1308 0x8000001A 0x000F99
Summary ASB Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
5.5.5.5 1.1.1.1 3 (DNA) 0x80000001 0x0003DF
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 125 0x80000057 0x00BE05 2
5.5.5.5 5.5.5.5 1946 0x80000059 0x0008E6 6
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 2.2.2.2 125 0x8000004D 0x00647D
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
172.16.1.0 5.5.5.5 945 0x8000004E 0x00A5E3 0
As we see above it shows us Area 0 and Area 2 database.
But below Database Type - 5 As does not have any area name -- like Area 0 or 2.************************************************
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 4.4.4.4 754 0x8000002D 0x006A0C 1
64.59.135.150 4.4.4.4 754 0x800003AE 0x00F5B2 0
172.16.1.0 5.5.5.5 1195 0x80000017 0x003092 0
172.31.0.0 4.4.4.4 754 0x8000002E 0x008475 0
172.31.1.0 4.4.4.4 754 0x8000002E 0x00797F 0
172.31.2.0 4.4.4.4 754 0x8000002E 0x006E89 0
172.31.3.0 4.4.4.4 754 0x8000002E 0x006393 0
My question is how do we tell know that Type -5 AS belongs to which area ??????????????
Thanks
MAhesh
Solved! Go to Solution.
12-17-2011 02:18 PM
Hello Mahesh,
So it means that Route 172.31.0.0 does not belong to any particular area and as per you It is domain-wide right?
Correct.
Best regards,
Peter
12-17-2011 01:26 PM
Hello Mahesh,
Your question is very valid. The explanation is simple - an LSA5 does not belong to any particular area because it describes an external network, i.e. a network that is outside your OSPF domain, not in any of its areas. Therefore it is not assigned to any particular area. It is domain-wide.
Of course you may be interested in which area is the ASBR located that imports this external route. There is a limited possibility for learning it. You need to have a look at the Advertising Router field in the corresponding LSA5 and search for it between LSA1 (if it is in one of your own areas), or between LSA4 if it is in a different area. However, if a LSA4 describes that ASBR, you cannot tell from your own link state database where the ASBR is located. You would need to go to the router that originated the LSA4 (that would obviously be an ABR) and look into its own database for corresponding LSA1 or LSA4, optionally proceeding even further in the same way.
Feel welcome to ask further.
Best regards,
Peter
12-17-2011 02:15 PM
Hi Peter,
Thanks for reply.
I login to Router -- ID 4.4.4.4
I did sh ip ospf database
2691Router#sh ip ospf database
OSPF Router with ID (4.4.4.4) (Process ID 1)
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 4.4.4.4 506 0x8000002F 0x00660E 1
64.59.135.150 4.4.4.4 506 0x800003B0 0x00F1B4 0
172.16.1.0 5.5.5.5 982 0x80000019 0x002C94 0
172.31.0.0 4.4.4.4 506 0x80000030 0x008077 0
172.31.1.0 4.4.4.4 506 0x80000030 0x007581 0
172.31.2.0 4.4.4.4 509 0x80000030 0x006A8B 0
172.31.3.0 4.4.4.4 509 0x80000030 0x005F95 0
2691Router#
Here also it shows Type 5 .
This is what i did on 2691 originating Router --------
I had configured them as static Route
ip route 172.31.0.0 255.255.255.0 Null0
ip route 172.31.1.0 255.255.255.0 Null0
ip route 172.31.2.0 255.255.255.0 Null0
ip route 172.31.3.0 255.255.255.0 Null0
router ospf 1
router-id 4.4.4.4
log-adjacency-changes
redistribute static metric 50 metric-type 1 subnets router ospf 1
So in this example we can say that 172.31.0.0 as it is external route and we redistribute it into OSPF domain and
ASBR router which is 2691 advertise it as Type 5 LSA to other OSPF speaking routers in Area 0 and 1.
So it means that Route 172.31.0.0 does not belong to any particular area and as per you It is domain-wide right?
Thanks
Mahesh
12-17-2011 02:18 PM
Hello Mahesh,
So it means that Route 172.31.0.0 does not belong to any particular area and as per you It is domain-wide right?
Correct.
Best regards,
Peter
12-17-2011 02:31 PM
Hi Peter,
Thanks for the reply.
Now my concept is clear.
Regards
MAhesh
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