From: Ivan Walker (ivan@itpro.co.nz)
Date: Tue Feb 24 2009 - 18:50:59 ARST
There is slight difference between the two solutions:
With Narbik's solution the default route will appear in the routing able
of the router originating the default (even if it points to null). With
Dales solution the default route will NOT be in the routing table of the
outer originating the default - there will be the dummy route though.
Probably doesn't make much difference except if a requirement on a
question needs to be met.
Ivan
Narbik Kocharians wrote:
> Dale,
>
> You know that i don't like to configure or see extra commands, please
> understand that i am NOT picking on your excellent solution here, but you
> did not have to go through extra configurations to accomplish this task,
> remember that OSPF will NOT inject a default route unless it has one to
> begin with or its tied to a condition like a route-map, therefore, instead
> of writing a static route to a fake network and then remove it when the
> operation of the SLA fails, you could have done the following:
>
> ip route 0.0.0.0 0.0.0.0 null0 track 1
>
> router ospf 1
> default-information originate
>
> Note, did not need the route-map and the fake route. If the operation of the
> SLA is unsuccessful, then the default route is removed and OSPF will remove
> the default route.
>
> No matter which way you go, you still wont need the "*always*" keyword
> because you are referencing a route-map.
>
> Thanks
>
> On Mon, Feb 23, 2009 at 11:30 PM, Thameem Maranveetil Parambath <
> tparamba@thecontactcentre.ae> wrote:
>
>
>> Hi Dale,
>>
>> That was a great workaround!
>>
>> Regards,
>>
>>
>>
>>
>>
>> Dale Shaw <dale.shaw@gmail.com>
>> Sent by: nobody@groupstudy.com
>> 24/02/2009 11:09 AM
>> Please respond to
>> Dale Shaw <dale.shaw@gmail.com>
>>
>>
>> To
>> ccie <ccie@just-horizon.com>
>> cc
>> ccielab@groupstudy.com
>> Subject
>> Re: How I can inject a default route into the OSPF upon the availability
>> of a ping to certain destination?
>>
>>
>>
>>
>>
>>
>> Hi,
>>
>> On Tue, Feb 24, 2009 at 5:36 PM, ccie <ccie@just-horizon.com> wrote:
>>
>>> Hi Experts,
>>>
>>> How I can inject a default route into the OSPF upon the availability of
>>>
>> a
>>
>>> ping to certain destination?
>>>
>> This is really rough but I tested it and it does work:
>>
>> ip sla monitor 10
>> type echo protocol ipIcmpEcho 10.1.13.3 source-interface Serial0/0/0.13
>> timeout 500
>> threshold 1000
>> frequency 5
>> ip sla monitor schedule 10 life forever start-time now
>> !
>> track 1 rtr 10
>> !
>> ip route 1.1.1.1 255.255.255.255 Null0 track 1
>> !
>> ip prefix-list STEER seq 5 permit 1.1.1.1/32
>> !
>> route-map CHEESE permit 10
>> match ip address prefix-list STEER
>> !
>> router ospf 10
>> default-information originate always route-map CHEESE
>>
>> - static route 1.1.1.1/32 is only 'up' if pings to 10.1.13.3 are
>> succeeding
>> - default-originate uses route-map which requires 1.1.1.1/32 to be in
>> the routing table
>>
>>
>>> And How I can inject a default route into the OSPF upon the availability
>>>
>> of
>>
>>> a directly connected link?
>>>
>> interface Lo0
>> !
>> ! this is the directly connected interface we want to use as part of
>> the condition
>> !
>> ip address 1.1.1.1 255.255.255.255
>> !
>> ip prefix-list LOOPBACK0-IP seq 5 permit 1.1.1.1/32
>> !
>> route-map CHEESE permit 10
>> match ip address prefix-list LOOPBACK0-IP
>> !
>> router ospf 10
>> default-information originate always route-map CHEESE
>>
>> (I quickly tried 'match interface' but that did not work.)
>>
>> cheers,
>> Dale
>>
>>
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