Mahendra,
On 23/02/18 05:48 , Mahendra Singh Negi wrote:
Dear Authors,
Amidst implementing conflict resolution for OSPF SR (
https://tools.ietf.org/html/draft-ietf-spring-conflict-resolution-05) we
came across this issue.
**
**
*Topology:*
*Issue:*
1.Prefix conflict occurs at RT1 and RT2.
2.Both RT1 and RT2 resolve the conflict and download corresponding Label
for SID:1 (SID:1 wins conflict resolution).
3.Both RT1 and RT2 advertise inter-area Extended Prefix Opaque LSA for
prefix 10.10.10.10 in area a1 with SID:1.
Reference:
https://tools.ietf.org/html/draft-ietf-ospf-segment-routing-extensions-24#section-7.2
&
https://tools.ietf.org/html/draft-ietf-ospf-segment-routing-extensions-24#section-5
(If an OSPF router advertises multiple Prefix-SIDs for the same
prefix, topology and algorithm, all of them MUST be ignored.)
which router advertises multiple Prefix-SIDs for the same prefix in your
example?
4.Now at RT1, user *changes the SID configuration value to 4*, and
still SID 1 wins the conflict resolution as in area a1 RT2 has not
flushed or updated SID:1, and SID:1 is forever in LSDB.
I don't understand the above. Why would that happen?
Peter
*How to fix the issue?*
a)think ABRs should advertise all the SIDs to leaking areas and MUST
condition mentioned highlighted in yellow above be relaxed(i.e. update
inter-area segment routing section accordingly) and let each node run
conflict-resolution.
b) On SID configuration change, RT1 Flushes the SID:1 and waits for
SID:1 flushing out from the LSDB and then originates with new SID:4.(How
long to wait is decided locally).
I prefer (a), if you please provide your opinion on this.We are under
development, highly appreciate prompt responses.
Regards,
Mahendra
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