Redistribute EIGRP to OSPF question

[mwilson]

Hello!  I am trying to redistribute EIGRP routes into OSPF.  Everything is working fine.  However, I am redistributing them into area 0.  My question is "Should they be?".

My initial plan was to have a separate area to bring the EIGRP routes into.  How do I accomplish that?  I believe I could run 2 separate OSPF instances and do it that way.  Any thoughts would be appreciated.  Thanks.!

[Joseph W. Doherty]

You don't need two instances of OSPF.

If you want to redistribute into another area, all you need to do is redistribute from another area's router assuming the other area type is of a kind that will accept external redistribution.

As to whether there's an advantage of not redistributing directly into area zero, redistribution into a non zero area may allow route filtering at the ABR (besides the ASBR).

[mwilson]

Joseph,

 Thank you.  The router I am redistributing EIGRP into is the ABR.  It is in both area 0 and 5.  When I redistribute they go to area 0 and not 5.  I'm not sure how to force them to area 5.  Thanks.

Mike

[Georg Pauwen]

Hello,

on a side note, and in addition to Joseph's post, when you redistribute EIGRP into OSPF, the redistributed routes are not part of a specified OSPF area, but rather show up as 'Type-5 AS External Link States. You can see that when you display the OSPF database after redistribution. Here is an example:

router ospf 1
redistribute eigrp 1 metric 100 subnets
network 2.2.2.2 0.0.0.0 area 1
network 192.168.2.0 0.0.0.255 area 0

R2#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
2.2.2.2 2.2.2.2 502 0x80000003 0x0057ED 1
3.3.3.3 3.3.3.3 1380 0x80000003 0x002EF3 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
192.168.2.1 2.2.2.2 1380 0x80000001 0x006C45

Summary Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
2.2.2.2 2.2.2.2 1467 0x80000001 0x00FA31

Router Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 502 0x80000003 0x00AB69 1

Summary Net Link States (Area 1)

Link ID ADV Router Age Seq# Checksum
3.3.3.3 2.2.2.2 1376 0x80000001 0x00D650
192.168.2.0 2.2.2.2 1457 0x80000001 0x008F39

Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag
1.1.1.1 2.2.2.2 502 0x80000001 0x00A0A3 0
192.168.1.0 2.2.2.2 502 0x80000001 0x0012CB 0
R2#

[Joseph W. Doherty]

What kind of area is area 5?  Again, some non zero areas will not accept externals.