[c-nsp] OSPF Default Route Injection

[David Granzer]

Hi Kevin,

I think this is not the case. Only routers which performs default
route injection (i.e. configured with default-information originate
always) doesn't see each others default route. There are no problem
with other routers in the network, they already have default route in
their routing table.

Best Regards,
David


On Fri, Mar 19, 2010 at 6:23 PM, Leah Lynch (Contractor)
<leah.lynch at clearwire.com> wrote:
> This is related to the forwarding address of 0.0.0.0; check this out:
>
> https://www.cisco.com/application/pdf/paws/13682/10.pdf
>
> It should help you fix it.
>
> Leah
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of David Granzer
> Sent: Friday, March 19, 2010 12:28 AM
> To: Kevin Hatem; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] OSPF Default Route Injection
>
> 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 <Kevin.Hatem at pgs.com> 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: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of David Granzer
>> Sent: Thursday, March 18, 2010 09:13
>> To: cisco-nsp at puck.nether.net
>> 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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