>
> -@item 5. Origin check.
> +@item 7. IGP cost check
> +Prefer the route with the lower IGP cost.
> +
> +@item 8. Multi-path check
> +If multi-pathing is enabled, then check whether
> +the routes not yet distinguished in preference may be considered equal. If
> +@ref{bgp bestpath as-path multipath-relax} is set, all such routes are
> +considered equal, otherwise routes received via iBGP with identical
> AS_PATHs
> +or routes received from eBGP neighbours in the same AS are considered
> equal.
> +
>
I think here we need to mention that if the two paths are both eBGP and
compare router-id is NOT configured, then we prefer the older of the two.
I think that will help with explaining the router-id knob later.
> +
> +@item 10. Router-ID check
> +Prefer the route with the lowest router-ID. If the
> +route has an ORIGINATOR_ID attribute, through iBGP reflection, then that
> +router ID is used, otherwise the router-ID of the peer the route was
> +received from is used.
> +
> +@item 11. Cluster-List length check
> +The route with the shortest cluster-list
> +length is used. The cluster-list reflects the iBGP reflection path the
> +route has taken.
> +
> +@item 12. Peer address
> +Prefer the route received from the peer with the higher
> +transport layer address, as a last-resort tie-breaker.
>
> -@item 6. MED check.
> @end table
>
> @deffn {BGP} {bgp bestpath as-path confed} {}
> @@ -125,11 +174,35 @@ decision process.
> @end deffn
>
> @deffn {BGP} {bgp bestpath as-path multipath-relax} {}
> +@anchor{bgp bestpath as-path multipath-relax}
> This command specifies that BGP decision process should consider paths
> of equal AS_PATH length candidates for multipath computation. Without
> the knob, the entire AS_PATH must match for multipath computation.
> @end deffn
>
> +@deffn {BGP} {bgp bestpath compare-routerid} {}
> +@anchor{bgp bestpath compare-routerid}
> +
> +Ensure that when comparing routes where both are equal on most metrics,
> +including local-pref, AS_PATH length, IGP cost, MED, that the tie is
> broken
> +based on router-ID.
> +
>
> * +If this option is enabled, then the external-age check, where already
> +selected eBGP routes are preferred, is skipped.*
> +
>
I think one sentence is mainly what need here....mabye change "where
already selected eBGP routes are preferred" to "where the oldest eBGP route
is preferred".
> +If a route has an ORIGINATOR_ID attribute because it has been reflected,
> +that ORIGINATOR_ID will be used. Otherwise, the router-ID of the peer the
> +route was received from will be used.
>
I would chop the paragraph above since this is already mentioned in the
bestpath explanation for router-id.
> +
> +The advantage of this is that the route-selection (at this point) will be
> +more deterministic. The disadvantage is that a few or even one
> +lowest-ID router may attract all trafic to otherwise-equal paths because
> of
> +this check. The exact behaviour will be sensitive to the iBGP and
> +reflection topology.
>
Ack on everything else. Thanks for putting this together Paul
Daniel
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