MPLS TE tunnel loadsharing

Below is from Pete Templin's post at www.routerie.com

Logical interfaces can go down. Only loopbacks and null0 don't go down unless administratively shut down.

In the case of TE tunnels, if the tunnel can't signal a path to the tunnel destination with the requested resources (X bandwidth for the configured tunnel priority with the configured tunnel affinity), it WILL go down. In the case of the TE tunnels shown, it will try to signal a path (using make-before-break if the tunnel is currently up) over the configured path-options in increasing numerical order.

As far as the load sharing, it won't be exactly 4:1. CEF has 16 buckets per destination. Those buckets can each have a single exit interface, and all 16 buckets must have an assigned exit interface. 13:3 is perhaps the closest ratio to 4:1 that fits the 16 bucket criteria. Additionally, the flows will be split across the buckets in the ratio selected; if some flows are higher bandwidth than others, the resulting load sharing may appear to be mismatched when looking at bandwidth.