Hi,
I have test setup with three routers R2/R3/R4, they running OSPF, R2
and R3 injecting default with "default-information originate always
metric 20", R4 already sees default route from both
R4#sh ip route 0.0.0.0
Routing entry for 0.0.0.0/0, supernet
Known via "ospf 2", distance 110, metric 20, candidate default path
Tag 2, type extern 2, forward metric 10
Last update from 10.0.0.13 on FastEthernet0/1, 00:01:26 ago
Routing Descriptor Blocks:
* 10.0.0.13, from 150.0.0.3, 00:01:26 ago, via FastEthernet0/1
Route metric is 20, traffic share count is 1
Route tag 2
10.0.0.9, from 150.0.0.2, 00:01:26 ago, via FastEthernet0/0
Route metric is 20, traffic share count is 1
Route tag 2
but R2 doesn't have default route from R3 installed in routing table
and vice versa. R2 and R3 sees external LSA from each other but
without Routing Bit set.
R3#sh ip route 0.0.0.0
% Network not in table
R3#sh ip ospf data ex 0.0.0.0
OSPF Router with ID (150.0.0.3) (Process ID 2)
Type-5 AS External Link States
LS age: 484
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 0.0.0.0 (External Network Number )
Advertising Router: 150.0.0.2
LS Seq Number: 80000001
Checksum: 0xB451
Length: 36
Network Mask: /0
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 2
LS age: 482
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 0.0.0.0 (External Network Number )
Advertising Router: 150.0.0.3
LS Seq Number: 80000001
Checksum: 0xAE56
Length: 36
Network Mask: /0
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 2
Best Regards,
David
On Thu, Mar 18, 2010 at 6:34 PM, Kevin Hatem <[email protected]> wrote:
> If two routers are injecting a default route under OSPF then each router will
> retain their own default route in the route table as each other's injected
> default route has the same distance as its self advertised default. You
> could set a higher/lower distance on inbound advertisements from the
> neighbors to influence the installation of the default route into the RIB.
>
> HTH
> -kevin
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of David Granzer
> Sent: Thursday, March 18, 2010 09:13
> To: [email protected]
> Subject: [c-nsp] OSPF Default Route Injection
>
> Hello,
>
> please could someone explain what exactly command "default-information
> originate always" under ospf process works ? When you have more than
> one router configured with this default route injection is correct
> behavior that you don't see on these routers default route in their ip
> routing table from other routers and you see only external lsa for
> 0.0.0.0 in ospf database ?
>
> Thanks,
> David
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