On Tue, Mar 23, 2010 at 12:43, Marc La Porte <marc.a.laporte_at_gmail.com> wrote:
> Hi,
>
> According to Doyle (page 418): "OSPF will advertise a secondary network or
> subnet only if it is also running on the primary network or subnet".
>
> This means that in order to advertise a secondary network/subnet, the
> primary network/subnet also needs to be advertised in OSPF. Removing the
> primary advertisement basically means disabling the secondary advertisement.
>
> Do both have to be in the same OSPF process? Or can this be on different
> OSPF processes?
They both must be in the same process, as you can't have more than one
process active on the interface.
Here's the quick lablet (is that a word - I like it?).
Let's give it a test
{Fa0/1}--R1----R2
R1:
interface FastEthernet0/0
ip address 12.12.12.1 255.255.255.0
!
interface FastEthernet0/1
ip address 1.1.1.1 255.255.255.0
ip address 11.11.11.11 255.255.255.0 secondary
!
router ospf 1
router-id 12.12.12.1
network 11.11.11.11 0.0.0.0 area 0
network 12.12.12.1 0.0.0.0 area 0
!
R2:
interface GigabitEthernet0/0
ip address 12.12.12.2 255.255.255.0
!
router ospf 1
router-id 12.12.12.2
log-adjacency-changes
network 12.12.12.2 0.0.0.0 area 0
!
Let's see if R2 has 11.11.11.0/24:
ProctorLabs-R2#show ip ospf database router 12.12.12.1
OSPF Router with ID (12.12.12.2) (Process ID 1)
Router Link States (Area 0)
LS age: 198
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 12.12.12.1
Advertising Router: 12.12.12.1
LS Seq Number: 80000004
Checksum: 0xF7A2
Length: 36
Number of Links: 1
Link connected to: a Transit Network
(Link ID) Designated Router address: 12.12.12.2
(Link Data) Router Interface address: 12.12.12.1
Number of TOS metrics: 0
TOS 0 Metrics: 1
It's not there. Let's add primary address of R1's Fa0/1 to OSPF and
observe then:
R1:
router ospf 1
network 1.1.1.1 0.0.0.0 area 0
!
ProctorLabs-R2#show ip ospf database router 12.12.12.1
OSPF Router with ID (12.12.12.2) (Process ID 1)
Router Link States (Area 0)
LS age: 5
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 12.12.12.1
Advertising Router: 12.12.12.1
LS Seq Number: 80000005
Checksum: 0xE66C
Length: 60
Number of Links: 3
Link connected to: a Stub Network
(Link ID) Network/subnet number: 1.1.1.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1
Link connected to: a Stub Network
(Link ID) Network/subnet number: 11.11.11.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1
Link connected to: a Transit Network
(Link ID) Designated Router address: 12.12.12.2
(Link Data) Router Interface address: 12.12.12.1
Number of TOS metrics: 0
TOS 0 Metrics: 1
It's there. Let's remove the secondary network from R1 and create new
OSPF 2 process to see if we can activate it on secondary address on
R1. We'll need to have one more interface.
R1:
interface Loopback1
ip address 111.111.111.111 255.255.255.0
!
router ospf 2
network 111.111.111.111 0.0.0.0 area 0
network 11.11.11.11 0.0.0.0 area 0
!
ProctorLabs-R1#show ip ospf 2 data router 111.111.111.111
OSPF Router with ID (111.111.111.111) (Process ID 2)
Router Link States (Area 0)
LS age: 73
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 111.111.111.111
Advertising Router: 111.111.111.111
LS Seq Number: 80000001
Checksum: 0xB246
Length: 36
Number of Links: 1
Link connected to: a Stub Network
(Link ID) Network/subnet number: 111.111.111.111
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
It's obviously not there - it's still a secondary address. Let's add
the primary address to OSPF 2 and see what happens:
router ospf 2
network 1.1.1.1 0.0.0.0 area 0
!
ProctorLabs-R1#show ip ospf 1 database router 12.12.12.1
OSPF Router with ID (12.12.12.1) (Process ID 1)
Router Link States (Area 0)
LS age: 229
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 12.12.12.1
Advertising Router: 12.12.12.1
LS Seq Number: 80000006
Checksum: 0xF3A4
Length: 36
Number of Links: 1
Link connected to: a Transit Network
(Link ID) Designated Router address: 12.12.12.2
(Link Data) Router Interface address: 12.12.12.1
Number of TOS metrics: 0
TOS 0 Metrics: 1
ProctorLabs-R1#show ip ospf 2 database router 111.111.111.111
OSPF Router with ID (111.111.111.111) (Process ID 2)
Router Link States (Area 0)
LS age: 79
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 111.111.111.111
Advertising Router: 111.111.111.111
LS Seq Number: 80000002
Checksum: 0x5C55
Length: 60
Number of Links: 3
Link connected to: a Stub Network
(Link ID) Network/subnet number: 111.111.111.111
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
Link connected to: a Stub Network
(Link ID) Network/subnet number: 1.1.1.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1
Link connected to: a Stub Network
(Link ID) Network/subnet number: 11.11.11.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 1
What has happened is that primary network of Fa0/1 has been removed
from OSPF 1 and was moved to OSPF 2. Don't be confused by
running-config - it is going to lie to you:
ProctorLabs-R1#show running-config | section router ospf
router ospf 1
router-id 12.12.12.1
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 11.11.11.11 0.0.0.0 area 0
network 12.12.12.1 0.0.0.0 area 0
router ospf 2
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 11.11.11.11 0.0.0.0 area 0
network 111.111.111.111 0.0.0.0 area 0
Hope this helps...
-- Marko Milivojevic - CCIE #18427 Senior Technical Instructor - IPexpert YES! We include 400 hours of REAL rack time with our Blended Learning Solution! Mailto: markom_at_ipexpert.com Telephone: +1.810.326.1444 Fax: +1.810.454.0130 Web: http://www.ipexpert.com/ Blogs and organic groups at http://www.ccie.netReceived on Tue Mar 23 2010 - 13:09:16 ART
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