From: Hobbs (deadheadblues@gmail.com)
Date: Wed Feb 11 2009 - 23:35:37 ARST
That's interesting. So it looks like what I am trying to do is not
possible and should not be...
btw, I was able to alter the distance of routes that R2 originated, if
R2 was the only hop and not load balanced with R5. If there was a tie
between R5 and R2, it looks like the distance applied to R5 took
effect (AD=100), but both routes were impacted.
thanks!
On Wed, Feb 11, 2009 at 6:09 PM, Daniel Kutchin <daniel@kutchin.com> wrote:
> Beware of bug CSCeh46993 on code 12.4
>
> "distance should not affect ospf path selection within a single process"
>
>
> -
>
> Daniel
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Hobbs
> Sent: Donnerstag, 12. Februar 2009 01:06
> To: Brian McGahan
> Cc: Cisco certification
> Subject: Re: OSPF distance command, router-id + wildcard mask
>
> Sorry, I should say in my previous example that R5 ended up using R2
> as transit to 192.168.61.0.
>
> On Wed, Feb 11, 2009 at 5:01 PM, Hobbs <deadheadblues@gmail.com> wrote:
>> I think I figured it out. This only works for directly connected
>> neighbors. When I use the distance command for 2.2.2.2, nothing
>> happens. It's still weird that it would affect LSAs that are not
>> generated by the router though...I guess it applies the distance to
>> all routes learned by that router.
>>
>> Another example:
>>
>> 192.168.61.0 is between R1 and R6.
>> R4 learns this route through R5 right now and has a distance of 100:
>>
>> R4#sho ip route 192.168.61.0
>> Routing entry for 192.168.61.0/24
>> Known via "ospf 1", distance 100, metric 3, type inter area
>> Last update from 192.168.45.5 on Serial1/0, 00:03:26 ago
>> Routing Descriptor Blocks:
>> * 192.168.45.5, from 5.5.5.5, 00:03:26 ago, via Serial1/0
>> Route metric is 3, traffic share count is 1
>>
>> By manipulating cost I can have R4 choose the path through R3:
>>
>> R5(config)#int s1/0
>> R5(config-if)#ip ospf cost 10
>>
>> Now the LSA that is actually used to build the route entry is from R2,
>> and the distance command is not applied anymore (even though R2 ends
>> up using R5 as transit/load balancing))
>>
>> R4#sho ip route 192.168.61.0
>> Routing entry for 192.168.61.0/24
>> Known via "ospf 1", distance 110, metric 4, type inter area
>> Last update from 192.168.34.3 on Serial1/1, 00:01:10 ago
>> Routing Descriptor Blocks:
>> * 192.168.45.5, from 5.5.5.5, 00:01:11 ago, via Serial1/0
>> Route metric is 4, traffic share count is 1
>> 192.168.34.3, from 2.2.2.2, 00:01:11 ago, via Serial1/1
>> Route metric is 4, traffic share count is 1
>>
>>
>> Kind of interesting, it looks like OSPF uses one LSA to install the
>> route, but if multiple paths exists, i will install both paths.
>> However the distance command works on the LSA that was
>> installed...maybe not the correct way to explain it, still a little
>> fuzzy...
>>
>> On Wed, Feb 11, 2009 at 4:51 PM, Hobbs <deadheadblues@gmail.com> wrote:
>>> Here you go:
>>>
>>> R4#sho ip route 1.1.1.1
>>> Routing entry for 1.1.1.1/32
>>> Known via "ospf 1", distance 100, metric 4, type inter area
>>> Last update from 192.168.45.5 on Serial1/0, 00:00:08 ago
>>> Routing Descriptor Blocks:
>>> 192.168.45.5, from 5.5.5.5, 00:00:08 ago, via Serial1/0
>>> Route metric is 4, traffic share count is 1
>>> * 192.168.34.3, from 2.2.2.2, 00:00:08 ago, via Serial1/1
>>> Route metric is 4, traffic share count is 1
>>>
>>> Here is a drawing of my topology
>>> http://imagebin.ca/view/st0dcn6.html
>>>
>>> thanks,
>>>
>>> On Wed, Feb 11, 2009 at 4:38 PM, Brian McGahan
>>> <bmcgahan@internetworkexpert.com> wrote:
>>>> Post the output of "show ip route 1.1.1.1".
>>>>
>>>> Brian McGahan, CCIE #8593 (R&S/SP/Security)
>>>> bmcgahan@internetworkexpert.com
>>>>
>>>> Internetwork Expert, Inc.
>>>> http://www.InternetworkExpert.com
>>>> Toll Free: 877-224-8987 x 705
>>>> Outside US: 775-826-4344 x 705
>>>>
>>>>
>>>>
>>>> Hobbs wrote:
>>>>
>>>> I have R4 as an internal router to Area 1.
>>>> R2 and R5 are border routers generating a type-3 LSA for route 1.1.1.1
>>>> into area 1.
>>>> Instead of using cost, I would like to use distance (if possible) to
>>>> alter path selection.
>>>>
>>>> R4 has two routes to 1.1.1.1
>>>> :
>>>>
>>>> R4#sho ip route | sec 1.1.1.1
>>>> O IA 1.1.1.1 [110/4] via 192.168.45.5, 00:01:10, Serial1/0
>>>> [110/4] via 192.168.34.3, 00:01:10, Serial1/1
>>>> R4#
>>>>
>>>> Here we see both type-3 LSAs, one each generated by R2 and R5:
>>>>
>>>> R4#sho ip osp database
>>>>
>>>> Summary Net Link States (Area 1)
>>>>
>>>> Link ID ADV Router Age Seq# Checksum
>>>> 1.1.1.1 2.2.2.2 207 0x80000001 0x0033FB
>>>> 1.1.1.1 5.5.5.5 170 0x80000002 0x00E040
>>>>
>>>>
>>>> R4(config)#router ospf 1
>>>> R4(config-router)#distance 100 5.5.5.5 0.0.0.0
>>>>
>>>> Both routes get changed:
>>>>
>>>> R4#sho ip route | sec 1.1.1.1
>>>> O IA 1.1.1.1 [100/4] via 192.168.45.5, 00:00:03, Serial1/0
>>>> [100/4] via 192.168.34.3, 00:00:03, Serial1/1
>>>>
>>>>
>>>> Why does the command alter both routes AD if I specified wildcard mask
>>>> of 0.0.0.0 ?
>>>>
>>>> I know that the ACL portion of the command works, to alter distance of
>>>> specific routes, but it appears the router-id/mask has no impact in
>>>> choosing between different ABR's.
>>>>
>>>> thank you,
>>>>
>>>>
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>>>>
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