[j-nsp] BGP Route Reflector

[Tay Chee Yong]

Hi Jesper,

Thanks for your pointer! We will do the necessary changes to resolve the
problem.

Regards,
Cheeyong


On Mon, 21 Apr 2003, Jesper Skriver wrote:

: On Mon, Apr 21, 2003 at 05:11:07PM +0800, Tay Chee Yong wrote:
: > Hi all,
: >
: > I have 2 route reflectors (Router A and Router B).
: > 2 RR clients (C and D)
: >
: > Both C and D are the clients of A and B
: > A and B are full mesh
: >
: > Both A and B are using the same cluster id, 1.1.1.1
: >
: > I then add router E to be client of B only, with some routes filtering.
: >
: > Strangely, router A is not selecting the better route from B learned from
: > E, instead router A is registering the better route from its learned eBGP
: > peer.
: >
: > Why aren't B propagating the better route learned from E to router A?
:
: A router reflector will discard all routes learned with it's own cluster
: id, see rfc2796 section 7, which say
:
:    CLUSTER_LIST
:
:    Cluster-list is a new optional, non-transitive BGP attribute of Type
:    code 10. It is a sequence of CLUSTER_ID values representing the
:    reflection path that the route has passed. It is encoded as follows:
:
:              0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
:     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:     |  Attr. Flags  |Attr. Type Code|   Length      | value ...
:     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
:    Where Length is the number of octets.
:
:    When a RR reflects a route, it must prepend the local CLUSTER_ID to
:    the CLUSTER_LIST.  If the CLUSTER_LIST is empty, it must create a new
:    one. Using this attribute an RR can identify if the routing
:    information is looped back to the same cluster due to mis-
:    configuration. If the local CLUSTER_ID is found in the cluster-list,
:    the advertisement received should be ignored.
:
: /Jesper
:
: