metric 0 vs 'no metric at all'

Tue Jan 3 15:27:43 UTC 2006

On Tue, 3 Jan 2006, Alexander Koch wrote:

> I was wondering if someone had done any or some research on this before...
> basically I am not sure with all the many implementations of BGP and all the
> vendors if and what those will do when they see a metric of 0 and no metric. I
> am not an expert knowing the actual protocol's messages exchanged, but I see
> some routes with nothing in the metric field on the various show commands, and
> some have explicit '0' metric.
> 
> I do not trust all the BGP implementations around, and we consider changing
> the default outbound, with MEDs of course still available on request.

i had this some time ago, cant remember where but i found some answers...

basically no metric is undefined, and can be handled either as all-zero or 
all-ones or anything you want really

the best practice was to set med manually to ensure the expected behaviour 
occurred.

Steve