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New Member

Resdistributing Eigrp Routes into OSPF

Hi All,

I was working on home Lab redistributing EIGRP  routes into OSPF.

R1 is router in OSPF domain.

R2 and R3 are redistributing  routers running both OSPF  and EIGRP.

R4 is router running EIGRP  only.

R1 has fas thernet connection to R2 and serial connection to R3

When i do sh ip route on R1  it shows routes learned by fast ethernet only

R1#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     10.0.0.0/24 is subnetted, 9 subnets
C       10.1.13.0 is directly connected, Serial0/0
C       10.1.12.0 is directly connected, FastEthernet0/0
C       10.1.0.0 is directly connected, Loopback0
O E2    10.4.2.0 [110/200] via 10.1.12.2, 00:13:36, FastEthernet0/0
O E2    10.4.3.0 [110/200] via 10.1.12.2, 00:13:36, FastEthernet0/0
O E2    10.4.0.0 [110/100] via 10.1.12.2, 00:13:36, FastEthernet0/0
O E2    10.4.1.0 [110/100] via 10.1.12.2, 00:13:36, FastEthernet0/0
O E2    10.1.24.0 [110/300] via 10.1.12.2, 00:13:36, FastEthernet0/0
O E2    10.1.23.0 [110/300] via 10.1.12.2, 00:13:36, FastEthernet0/0

Metric is same from R2 and R3  to R1.

So here is my thinking correct me if i am wrong  --------------

If router learned routes having same Admin distance and metric  from two routers.

it will choose the physical link which is faster as fast ethernet is more speed then serial T1 ??????

If it learn same routes via both serial links then it will load balance right??????????

Thanks

MAhesh

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Resdistributing Eigrp Routes into OSPF

For sure,

OSPF uses cumulative metric which is calculated based on Bandwidth. The last hop on serial interface will add bigger value to total value than Fast Ethernet link.

You should be able to see both routes in OSPF topology as it should have Type 5 LSA from both neighbors.

Nik

5 REPLIES
Cisco Employee

Resdistributing Eigrp Routes into OSPF

For sure,

OSPF uses cumulative metric which is calculated based on Bandwidth. The last hop on serial interface will add bigger value to total value than Fast Ethernet link.

You should be able to see both routes in OSPF topology as it should have Type 5 LSA from both neighbors.

Nik

New Member

Resdistributing Eigrp Routes into OSPF

Hi Nik,

Thanks  for reply.

i did this

R1#sh ip ospf database

            OSPF Router with ID (10.1.0.1) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
10.1.0.1        10.1.0.1        1789        0x80000024 0x00E3D0 4
10.1.23.3       10.1.23.3       44          0x8000001F 0x000BED 2
10.1.24.2       10.1.24.2       1220        0x80000021 0x00F0A3 1

                Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
10.1.12.2       10.1.24.2       1723        0x8000001E 0x00EAC2

                Type-5 AS External Link States

Link ID         ADV Router      Age         Seq#       Checksum Tag
10.1.23.0       10.1.23.3       44          0x80000003 0x0059C6 30
10.1.23.0       10.1.24.2       1220        0x8000001D 0x0024E1 30
10.1.24.0       10.1.23.3       44          0x80000003 0x004ED0 30
10.1.24.0       10.1.24.2       1220        0x8000001D 0x0019EB 30
10.4.0.0        10.1.23.3       44          0x80000003 0x00F21E 10
10.4.0.0        10.1.24.2       1220        0x8000001D 0x00BD39 10
10.4.1.0        10.1.23.3       63          0x80000003 0x00E728 10
10.4.1.0        10.1.24.2       1239        0x8000001D 0x00B243 10
10.4.2.0        10.1.23.3       63          0x80000003 0x007D23 20
10.4.2.0        10.1.24.2       1239        0x8000001D 0x00483E 20
10.4.3.0        10.1.23.3       63          0x80000003 0x00722D 20
10.4.3.0        10.1.24.2       1239        0x8000001D 0x003D48 20

where 10.1.23.3  is R3 and we can see that it is learning EIGRP routes from R3 also but it did not put that in routing

table because of  serial link speed right??

Mahesh

Cisco Employee

Resdistributing Eigrp Routes into OSPF

Correct

New Member

Resdistributing Eigrp Routes into OSPF

Hi Mahesh,

Your understanding is correct, The behaviour is because of the cost related to Serial interface,

Try to use the metric-type keyword during redistribution and you will see different result ( metric-type 1, Default is type 2 )

Regards

Sreenath

New Member

Resdistributing Eigrp Routes into OSPF

Hi Nik,

any thanks for correct explanation.

Thanks

MAhesh

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