Re: understanding redistribution

I said "same router" of course.

Tags aren't the silver bullet solution for all situations and can actually cause reachability problems in certain topologies. Also when preparing for the lab you need to look for other ways to solve problems without tags as there could be a good chance that you aren't allowed to use tags in the lab.

Brian Dennis, CCIEx5 #2210

On May 9, 2013, at 2:21 PM, "Tony Singh" <mothafungla_at_gmail.com> wrote:

> Ok you are you saying eigrp>ospf>bgp
>
> bgp will would need eigrp explicitly redistributing for it to learn the eigrp prefixes only on the same router right?
>
> How about no tags x to y then y back to x using different routers, like so.....this can cause double redistribution right?
>
> When I do tag I don't seem to get any hits i.e tag 20 from ospf>eigrp then deny that tag inbound under the ospf process
>
>
> Eigrp
> R1------------r2
> | |
> R3------------r4
> Ospf/eigrp
>
> --
> BR
>
> Tony
>
> Sent from my iPad
>
> On 9 May 2013, at 21:38, Brian Dennis <bdennis_at_ine.com> wrote:
>
>> You can tag all you want ;-) You can't get a route from protocol X to Y
>> and then to Z from Y on the same router.
>>
>> --
>> Brian Dennis, CCIEx5 #2210 (R&S/ISP-Dial/Security/SP/Voice)
>> bdennis_at_ine.com
>>
>> INE, Inc.
>> http://www.INE.com
>>
>>
>>
>>
>> On 5/9/13 1:00 PM, "Tony Singh" <mothafungla_at_gmail.com> wrote:
>>
>>> Hey where's your tagging & community lists to prevent double
>>> redistribution ;)
>>>
>>> Brian one thing when we enable tagging to prevent the original routes
>>> being re-learnt back in I never seem to get any hits on the route-maps in
>>> bytes....anyone seen this?
>>>
>>> Real gear btw
>>>
>>> --
>>> BR
>>>
>>> Tony
>>>
>>> Sent from my iPad
>>>
>>> On 9 May 2013, at 19:47, Brian Dennis <bdennis_at_ine.com> wrote:
>>>
>>>> If you redistribute protocol X into protocol Y, protocol X's routes
>>>> can't
>>>> go into protocol Z from protocol Y. You need to also redistribute
>>>> protocol X directly into protocol Z to get protocol X's routes into
>>>> protocol Z. This may not be easy to follow but it's important to
>>>> understand.
>>>>
>>>> The reason behind this is that redistribution is done from the RIB
>>>> (routing table) and not done directly between routing protocols. If you
>>>> redistribute protocol X into protocol Y then Y will get protocol X's
>>>> dynamic routes that are in the RIB (show ip route X) and for IPv4, by
>>>> default, the connected interfaces that protocol X is enabled on (i.e.
>>>> network statement, ip ospf 1 area 0, etc)
>>>>
>>>> So in your case if you didn't redistribute say static into BGP but are
>>>> redistributing static into EIGRP, BGP will not get the static routes
>>>> that
>>>> are redistributed into EIGRP when EIGRP is redistributed into BGP.
>>>>
>>>> --
>>>> Brian Dennis, CCIEx5 #2210 (R&S/ISP-Dial/Security/SP/Voice)
>>>> bdennis_at_ine.com
>>>>
>>>> INE, Inc.
>>>> http://www.INE.com
>>>>
>>>>
>>>>
>>>>
>>>> On 5/9/13 11:14 AM, "Cisco Fanatic" <ebay_products_at_hotmail.com> wrote:
>>>>
>>>>> I am not sure if I understand this. If we are mutually redistributing
>>>>> between
>>>>> say EIGRP and BGP does it matter which protocol we redistribute
>>>>> connected
>>>>> and
>>>>> static routes in?
>>>>>
>>>>> router eigrp 1000
>>>>> redistribute connected
>>>>> redistribute bgp 65001 metric 15000 5 255 1 4470 router bgp 65001
>>>>> redistribute static
>>>>> redistribute eigrp 1000
>>>>> ******** OR **************
>>>>
>>>>> router eigrp 1000
>>>>> redistribute static
>>>>> redistribute bgp 65001 metric 15000 5 255 1 4470 router bgp 65001
>>>>> redistribute connected
>>>>> redistribute eigrp 1000
>>>>> -Yuri
>>>>>
>>>>>
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Received on Thu May 09 2013 - 18:16:35 ART