Hi Peter, On 10/9/15, 11:34 AM, "Peter Psenak" <[email protected]> wrote:
>Hi Pushpasis, > >>> >>> Node N1 in area 1 advertises prefix P1 with SID X. ABR1 advertises P1 to >>> area 0. >>> Node N2 in area 2 advertises prefix P2 with SID X, ABR2 advertises P2 to >>> area 0. >>> >>> Node 3 in area 0 get these two prefixes P1 and P2 from two different >>> ABRs. How does it know that the originators for P1 and P2 are different? >>> Do you expect the ABR1 and ABR2 to detect the collision and withdraw SID >>> advertisement to area 0? If yes, that may become source of all sorts of >>> problems. >> [Pushpasis] Nodes in area 0 can see that for the same prefix there are two >> prefix-sid advertisements from ABR1 and ABR2 but another advertisement (not >> re-advertisement) from Node 3. > >there is no advertisement from Node 3 in this case. Node 3 is an >internal router in area 0 (non-ABR). How does node 3 figures out if the >prefixes P1 and P2 are sourced by the same node or not? Unless you carry >the originator-id with each prefix, I don't see how you can do that. [Pushpasis] I overlooked that there were two different prefixes P1 and P2 in your example. In that case I will take back my last comment and re-formulate the proposal. For the situation that you mentioned above, here is what how it should be dealt with.. 1. ABR1 and ABR 2 re-advertises the prefixes P1 and P2 into Area 0. 2. ABR1 will learn from ABR2’s advertisement in Area 0 that the same index is associated with P1 originated by N1 in Area 1 and and a different prefix P2 (re)originated from another node ABR2 in Area 0. It should then raise a syslog error notifying that this seems to be misconfiguration. 3. Likewise, ABR2 will learn from ABR1’s advertisement in Area 0 that the same index is associated with P2 originated by N2 in Area 2 and and a different prefix P1 (re)originated from another node ABR1 in Area 0. It should then raise a syslog error notifying that this seems to be misconfiguration. 4. And then none of the ABRs should withdraw the prefix-sid-advertisements (I take back my last comment). Things should be left as is till the operator rectifies the configuration. The basic rule for any node to detect a anomaly and take action should be as follows… A. Multiple prefix originated with same but from same originator.. No need to throw error B. Multiple prefix originated with same index but from different originator.. Throw syslog.. Use the index advertised with best-originator(s) of the prefix for MPLS ingress/transit routes. C. Same prefix originated with different index from same originator.. Throw syslog.. But don’t program MPLS ingress/transit routes for it… Ideally this scenario is almost next to impossible unless any implementation allows assoicating multiple sids with a singe prefix. D. Same prefix originated with different index from same originator.. Throw syslog.. Use the index advertised with best-originator(s) of the prefixfor MPLS ingress/transit routes. Hoping I have covered all possible situation with the above set of rules. Thanks -Pushpasis > >thanks, >Peter _______________________________________________ spring mailing list [email protected] https://www.ietf.org/mailman/listinfo/spring
