From: Toh Soon, Lim (tohsoon28@gmail.com)
Date: Thu Sep 13 2007 - 22:26:57 ART
Hi Ron,
Thanks for your reply.
My usual practice is I fix the OSPF router-id. Please see my config below:
ASBR in NSSA Area 1
-------------------
hostname R1
!
interface Loopback0
ip address 150.50.1.1 255.255.255.255
!
interface FastEthernet0/0
description *** Connection to NSSA ABR (router-id 150.50.2.2) ***
ip address 150.50.10.1 255.255.255.0
!
router ospf 1
router-id 150.50.1.1
log-adjacency-changes
area 1 nssa
redistribute rip subnets
network 150.50.10.1 0.0.0.0 area 1
!
Internal router in Area 0
-------------------------
R6#sh ip os da ex 192.168.1.0
OSPF Router with ID (150.50.6.6) (Process ID 1)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 69
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.1.0 (External Network Number )
Advertising Router: 150.50.2.2
LS Seq Number: 8000000C
Checksum: 0x8109
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 150.50.10.1
External Route Tag: 0
Without covering lo0 in Area 1 on R1, routers in Area 0 will receive the LSA
with Forward Address of 150.50.10.1 (R1's Fa0/0). Though it's not a
significant problem, I just want to have the right understanding of how OSPF
determines the forwarding address.
I understand that if the forwarding address is not reachable, the route will
not be installed in the RIB.
Thank you.
B.Rgds,
Lim TS
On 9/14/07, Ron Lim <gottobeccie@gmail.com> wrote:
>
> Hi Toh Soon,
>
> My understanding is the router-id specified on router OSPF else highest IP
> loopback address then highest IP interface (UP, UP) mode.
>
> Hope this helps!
>
> Regards,
> Ron
>
>
> On 9/14/07, Toh Soon, Lim <tohsoon28@gmail.com> wrote:
>
> > Hi Group,
> >
> > I have an ASBR in an NSSA. It is redistributing RIP into OSPF. I cover
> > it's
> > loopback interface in the NSSA area. The ABR of the NSSA is not
> > configured
> > to suppress the forwarding address when translating Type-7 to Type-5
> > LSAs.
> >
> > Other routers in Area 0 see the redistributed routes having the
> > Advertising
> > Router as the ABR's router-id and the Forward Address as the ASBR's
> > loopback
> > ip.
> >
> > When I remove the ASBR's loopback ip from the NSSA area, the Forward
> > Address
> > becomes the ASBR's interface IP address out which it advertised the
> > Type-7
> > LSAs.
> >
> > Can anyone tell me what is the normal behavior OSPF determines the
> > forwarding address? Appreciate your comments.
> >
> >
> > Thank you.
> >
> > B.Rgds,
> > Lim TS
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sat Oct 06 2007 - 12:01:11 ART