Hi all,
I’ve a strange problem on my CCR1036 (6.45.6).
I’ve many BGP session that are working fine, but some routes I receive have a unexplained behavior.
Who can explain to me this :
As you can see I’ve one Active route on three identical routes but that one, for what I can understand, should not be active.
The active route has a longer AS PATH and a lower BGP Weight. Obviously I need the other routes to be used.
Any ideas?
Thanks!
Emiliano
See https://wiki.mikrotik.com/wiki/Manual:BGP_Best_Path_Selection_Algorithm
Best path algorithm compares routes received by a single BGP instance. Routes installed by different BGP instances are compared by the general algorithm, i.e. route distances are compared and the route with lower distance is preferred.
All three routes in your screenshot have the same distance. If that is the case, https://wiki.mikrotik.com/wiki/Manual:Route_Selection_Algorithm_in_RouterOS mentions:
If there is more than one route with the same distance, selection is done in random
This explains the behaviour you see.
Huh, no. The selection is done in random if all the other attributes used by the bgp path selection are the same or does not exist !
Read the first link I posted. If the routes are received from peers using different BGP instances, they will not be compared according to the BGP best path selection algorithm.
Hi again,
problem found. (tnx FezzFest)
using multiple instances the bgp path selection doesn’t work as usually. I’ve to use the “distance” to select the best instance, after that the bgp selection algorithm finish the work.
THANKS all!!!
bye!