>In particular, suppose the filtering is based on metrics M1 and M2, and the >output is M3, for a set src to a set dsts. The Client can use the following >three queries:
>- Q1: Use single metric <M1, filter on M1, srcs, dsts> and obtains <srcs1, >dsts1> in return; >- Q2: Use single metric <M2, filter on M2, srcs1, dsts1> and obtains <srcs2, >dsts2> in return; >- Q3: Use single metric <M3, no filter, srcs2, dsts2> to get the final result. >Although this is not too bad, it is inconvenient. Note that preceding is first >discussed by Sabine, Wendy, Nico in: >http://tools.ietf.org/html/draft-randriamasy-alto-multi-cost-07 >I saw that this is also the issue discussed in >- http://tools.ietf.org/html/draft-wu-alto-json-te-01 >- http://tools.ietf.org/html/draft-lee-alto-app-net-info-exchange-02 >Hence, I propose that the WG extends the base protocol with this capability, >as I see that it is quite useful. One issue is that I see three designs, and I >am wondering if the authors are >preparing on discussing their designs at the coming IETF, and if there is a >possibility for a single, unified document, focusing on this issue. By comparing the designs in three drafts, here is my rough analysis. the difference between these drafts are: a. draft-randriamasy-alto-multi-cost-07 seems to assume filtering condition and output are based on the same Cost metrics or a set of same metrics. Both draft-lee-alto-app-net-info-exchange-02 and draft-wu-alto-json-te-01 allows filtering condition and output based on different cost metrics and therefore it require filtering constraint relaxing In the ALTO base protocol. b. draft-randriamasy-alto-multi-cost-07 specifies one new cost metrics (i.e.,pathoccupationcost) while draft-lee-alto-app-net-info-exchange-02 defines a new object called DstCostsConstraints which contains a list of cost metrics that are not stable over a constant period(i.e., they are dynamic parameters). draft-wu-alto-json-te-01 gives a complete list of those cost metrics based on IETF standardization work (see draft-ietf-idr-ls-distribution-03,RFC5305, draft-wu-idr-te-pm-bgp<http://tools.ietf.org/id/draft-wu-idr-te-pm-bgp-02.txt>,draft-ietf-ospf-te-metric-extensions-04, draft-ietf-isis-te-metric-extensions-00) and define them as a list of independent cost metrics. c. draft-randriamasy-alto-multi-cost-07 requires cost value encoded as JSON Array rather than JSON while draft-lee-alto-app-net-info-exchange-02 also encode cost value as JSON Array. In addition, draft-lee-alto-app-net-info-exchange-02 defines linkentry object and support representing a end to end path with a list of links traversed in the path. draft-wu-alto-json-te-01 also defines link related metrics and uses linkname to identify each link. Thanks a lot! Richard
_______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto
