Re: [Idr] draft-chen-bgp-redist-01.txt

[Gyan Mishra <[e-mail]>]

Hi Enke

My understanding is by default most all implementations that I know of for
example Cisco & Juniper which have use identical default AD, redistribution
of the route only occurs from the source protocol that is being
redistributed for example static versus OSPF or ISIS based on AD.

So if you have multiple protocols redistribution into BGP, the source
protocol with the lowest AD is what is inserted into the default RIB/FIB
and its that specific route from the source protocol that is redistributed
into BGP.   All implementations that I know of work that way.

I don’t see any issue with deterministic redistribution as exists today
with implementations.

Normally you are only running one IGP but let’s say you are running OSPF
and ISIS and you have a Juniper and Cisco ASBR redistribution into BGP, as
OSPF has default AD 110, the OSPF prefix would be inserted into the Default
RIB and redistributed into BGP.  Let’s say you set AD for ISIS down to 90
and now the ISIS route is inserted into the RIB and now both Juniper and
Cisco ASBR Will redistribute the ISIS route into BGP.

I am not seeing the issue that you are trying to solve.

Kind Regards

Gyan

On Wed, Jun 30, 2021 at 3:19 AM Enke Chen <[e-mail]>
wrote:

> Hi, Robert:
>
> 1) Usually the default admin-distance is configurable. Having the same
> admin-distance across implementations would certainly make things simpler,
> but that is not required. What matters is the local_pref value for the
> redistribute backup route:
>
>             local_pref = default_local_pref - delta;
>
> It needs to be in the right order (relatively) for the "role" the route is
> supposed to play.
>
> It's a good question. We will try to clarify it in the next revision.
>
> 2) Certainly it would work if we define the "delta" (or "local_pref") for
> the redistributed route based on its role (e.g., primary, secondary,
> tertiary). But extra config would be needed for specifying the "role".  The
> algorithm described in the draft does not require additional config other
> than the existing "admin-distance".  When more than two paths are involved
> in a multi-vendor environment, the admin-distance needs to be carefully
> assigned in order to get the desired local_pref value.
>
> Thanks.   -- Enke
>
> On Tue, Jun 29, 2021 at 1:05 PM Robert Raszuk <[e-mail]> wrote:
>
>> Hi Enke,
>>
>> How do you assure that admin distance is the same or delta would be the
>> same across implementations ?
>>
>> Looking at say junos I see quite different values then when comparing
>> with other implementations ...
>>
>>
>> https://www.juniper.net/documentation/en_US/junos/topics/reference/general/routing-protocols-default-route-preference-values.html
>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.juniper.net_documentation_en-5FUS_junos_topics_reference_general_routing-2Dprotocols-2Ddefault-2Droute-2Dpreference-2Dvalues.html&d=DwMFaQ&c=V9IgWpI5PvzTw83UyHGVSoW3Uc1MFWe5J8PTfkrzVSo&r=OPLTTSu-451-QhDoSINhI2xYdwiMmfF5A2l8luvN11E&m=iUboWFiSpP9QvSDj9hoG8_DO7R_8EOQvfEHnwyX-mc0&s=GOhXjwEf1z0GAfIQVgVAc4sHvcAog6czTO30VhKwzQk&e=>
>>
>> Would it be simpler to define here verbatim what the local pref should be
>> for redistributed routes ? Then at least those could be used as default
>> local pref values unless overwritten by operator's policy during
>> redistribution.
>>
>> Thx,
>> Robert
>>
>>
>> On Tue, Jun 29, 2021 at 7:14 PM Enke Chen <[e-mail]>
>> wrote:
>>
>>> Hi, Folks:
>>>
>>> Apologies for the very long delay in updating the draft:
>>>
>>>        https://datatracker.ietf.org/doc/draft-chen-bgp-redist/01/
>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_draft-2Dchen-2Dbgp-2Dredist_01_&d=DwMFaQ&c=V9IgWpI5PvzTw83UyHGVSoW3Uc1MFWe5J8PTfkrzVSo&r=OPLTTSu-451-QhDoSINhI2xYdwiMmfF5A2l8luvN11E&m=iUboWFiSpP9QvSDj9hoG8_DO7R_8EOQvfEHnwyX-mc0&s=IBn3kTJmGrWISvSq8L3M9GLLamXIqw7t2PvEdtvhmos&e=>
>>>
>>> The issue still exists, and shows up from time to time. The revised
>>> version provides a complete solution that covers the use cases involving a
>>> single router as well as multiple routers in a network.
>>>
>>> Your review and comments are welcome.
>>>
>>> Thanks.   -- Enke
>>>
>>>
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>>>
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*Gyan Mishra*

*Network Solutions A**rchitect *

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