Tricci, See comments below. Thanks, Jerry Ash > draft-ash-mpls-diffserv-te-alternative-02.txt > In section 3.2, although there are some brief descriptions on the intents of the > "admission-control priority classes" and "restoration priority classes". To me, it > is still unclear about why these two classes are needed in order to allow higher > priority LSP to be set up first and be protected first. More explanation on > the motivation on these types of priority classes would be very useful. More > importantly, how exactly they are being coordinated with each other when performing > the TE function? See the attached PDF document for further explanation of our thoughts on class types and the role of admission control priority and restoration priority. We plan to issue an I-D on this in the next few weeks. > I have a lot of trouble of trying to understand how to handle the crankback > situation for the example which is described in section 3.2 for the LSP setup at > the ingress and transit LSRs. Since there is no mention on how each node > recognizes the protected-CT-bandwidth level across the selected hops, when > performing crankback, how the crankback node recognizes which new hop to > select to set up the LSP. More details on this aspect for the example would > be extremely useful. As specified in the I-D on crankback http://search.ietf.org/internet-drafts/draft-iwata-mpls-crankback-01.txt, the transit LSR can either crankback to the ingress LSR or a border LSR. In the example, after a transit LSR recognizes that requirements are not met on the next hop (e.g., lack of sufficient available bandwidth), the transit LSR sends crankback to the ingress LSR. The ingress LSR then selects another LSP choice, based on several possible algorithms. The attached figure gives some further details of an example, see also http://www.ietf.org/internet-drafts/draft-ietf-tewg-qos-routing-01.txt (e.g., Section 3.4).
mpls.diffserv.te.class.types.082901.pdf
mpls.diffserv.te.lsp.selection.example.pdf