[routing-wg] May a tier1 transit change bgp origin attribute?

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Hi Job,

On 13.12.13 21:08, Job Snijders wrote:
> On Fri, Dec 13, 2013 at 08:31:39PM +0100, Harald Michl wrote:
> 
>> We (ACOnet, the Austrian NREN, AS1853) do have several upstreams.
>> More or less per random we detected that one of them delivers
>> prefixes with a different route origin parameter (IGP instead of
>> incomplete) than others. This obviously has a big influence in
>> the BGP best-path selection. After asking why this is the case we
>> learned from them:
>> 
>> On 28.11.13 10:32, support at xxx.com wrote:>
>>> Hi Harald,
>>> 
>>> The XXX standard route map sets origin IGP as standard across
>>> all customer learned routes...
>> 
>> Now we are currently debating with them whether this is ok or
>> not.
> 
> For me the igp attribute falls in same category as MED. If your
> routing policy is not to accept MEDs (thus rewriting them), you
> should for consistency purposes, also reset route origin attribute.
> 
Of course we could rewrite all origin attributes to be the same. But
that's like removing it from the best-path calculation. (this is not a
problem, just a conclusion)

> 
> It is likely your upstream is resetting the origin to draw more
> traffic towards themselves. To level the playing field in your
> case, it might be beneficial to reset origin on outbound
> advertisement across all your upstreams.

Yes attracting more traffic could be a reason. But I think there is no
reason why someone _has to_ rewrite the origin parameter. So I'd
expect this data set by origin not to be changed during the bgp
propagation.

I also wonder which attributes will be signed in a more secure BGP
environment in the long run. If the origin attribute is going to be
one of these parameters then signature-checks will/would fail...

- -Harald

> 
> Kind regards,
> 
> Job
> 
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