The MPLS WG Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] on documenting ECMP (was on the mpls oam framework)
Curtis, -> Without hierarchical LSPs, RSVP/TE does not have multipath unless 1) -> more than one LSP is configured to the same destination with equal -> cost and MP is enabled, or 2) more than one LSP is on a path to -> different egress and the total cost is the same, and this form of MP -> is both supported and enabled. This form of MP is easy to deal with -> from an OAM standpoint because the only branch is at ingress. Very delightful to read such a good technical explanation. But... what ever you said above that current MPLS signaling can't support ECMP at non-ingress branch point is a limitation. From MPLS-TE point of view, all the necessary information to split the traffic at non-ingress can be calculated easily. Unfortunately, signaling doesn't support that. If given a chance, such an ECMP split can be computed by ingress CSPF by finding all augmented "equal min-cost max-flow" paths to the destination. Chosing any of least/farthest such common ancestor split can be made as part of singaling decision. -> QoS based on EXP can be enabled and ECMP can also be -> enabled. If each -> branch of the path honors the EXP bits, QoS still works and exists in -> the presense of ECMP, over LDP or RSVP/TE. There is very clear -> existance proof of this. I view ECMP as a TE mechanism than a QoS workhorse. TE and QoS are infact orthogonal. Venkata.
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