Re: as-override vs. allowas-in

Well, with the allowas-in command, there's a # to say how many times it
can appear before considered looped. With replacing the AS it would
just look like someone prepended, so unless you have a rule/aversion to
prepending it wouldn't matter.

*Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,

JNCIE-M #153, JNCIS-ER, CISSP, et al.

JNCI-M, JNCI-ER

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Persio Pucci wrote:
> Hi Scott,
>
> Yeah, that was the only difference I could think of.
>
> Well, on the technical side, as-override will replace the origin AS with the
> MPLS cloud AS, while allowas-in will actually break the AS-PATH rule and
> allow the AS to be repeated, so I guess that could impact filtering and some
> other policy-related issues.
>
> I wonder if the protocol will do some sanity-check on the AS-PATH and drop a
> route that has a repeated AS inside, let's say, on a router in a connected
> AS that receives this route.
>
> On Fri, Jul 3, 2009 at 12:23 PM, Scott Morris <smorris_at_ine.com> wrote:
>
>
>> I suppose it depends on your perspective. Purely technical, no, not
>> really. They both allow the route to come in.
>>
>> Politically though, one you are solving on the SP side (presumably knowing
>> more than your customers do), the other you are forcing all your customers
>> to have different configurations with things they may not have a clue why.
>>
>> If you're doing managed CE routers, then there's no difference.
>>
>> My two cents.
>>
>>
>>
>>
>> *Scott Morris*, CCIE*x4* (R&S/ISP-Dial/Security/Service Provider) #4713,
>>
>> JNCIE-M #153, JNCIS-ER, CISSP, et al.
>>
>> JNCI-M, JNCI-ER
>>
>> evil_at_ine.com
>>
>>
>> Internetwork Expert, Inc.
>>
>> http://www.InternetworkExpert.com <http://www.internetworkexpert.com/>
>>
>> Toll Free: 877-224-8987
>>
>> Outside US: 775-826-4344
>>
>>
>> Knowledge is power.
>>
>> Power corrupts.
>>
>> Study hard and be Eeeeviiiil......
>>
>>
>>
>>
>>
>> Persio Pucci wrote:
>>
>> Hi there,
>>
>> Is there any pratical difference on whether using "as-override" on the PE
>> side instead of "allowas-in" on the CE when using BGP as the PE-CE protocol
>> with two sites using the same AS#?
>>
>> Persio
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
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>>
>
>
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Received on Fri Jul 03 2009 - 13:56:41 ART