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

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. 

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.

Kind regards,

Job
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