Hello,
I am announcing a /28 prefix from Router A to ROuter B by OSPF then Router B redistribute route by bgp to Router C but ROuter c detect the bgp origin of route as invalid/incomplete , how can I solve it and whats the problem?
Thank you.
This is normal for most BGP routes and does not indicate a problem. This is typically due to a route being redistributed into BGP.
Here are the origin types from the BGP-4 RFC (EGP is no longer used so it’s listed but not important anymore)
https://tools.ietf.org/html/rfc4271
a) ORIGIN (Type Code 1):
ORIGIN is a well-known mandatory attribute that defines the
origin of the path information. The data octet can assume
the following values:
Value Meaning
0 IGP - Network Layer Reachability Information
is interior to the originating AS
1 EGP - Network Layer Reachability Information
learned via the EGP protocol [RFC904]
2 INCOMPLETE - Network Layer Reachability
Information learned by some other means
any idea how can i solve it?
No, you can not change BGP origin in RouterOS
http://forum.mikrotik.com/t/set-bgp-origin-attribute-in-routeros/97725/1
What problem are you trying to solve?
when Router C receive the route it is not complete and it will not choose as best path, this is the issue
Is this your router?
You can change inbound wight, local preference, or administrative distance for this prefix. Or change another prefix attributes on inbound.
If it is not yours, but i assume this is your prefix, you can prepend it on the other path, or use MED.
If another prefix is not yours, you will have trouble anyway next time 
But you can ask your peer for communities or to change it on his side
If a route is not valid or active, it often means the next hop is unreachable. Check that first.
The factor that BGP origin (incomplete/igp) plays in route selection is so minor that it is unlikely that this is your problem.