All links have 1Gbps unreserved bandwidth initially and all LSPs have the least-fill feature enabled. After the two LSPs have been signaled as shown, two new
LSPs are configured. LSP-3 is signaled first with 600Mbps reserved. LSP-4 is signaled after with 800Mbps reserved. All LSPs have the same setup and hold priorities. Which paths will CSPF choose for LSP-3 and LSP-4?
Given that all links have 1Gbps of unreserved bandwidth initially and the least-fill feature is enabled, the path that will be chosen aims to use links with the least available bandwidth last. First, LSP-3 is signaled with a reservation of 600Mbps. Considering the initial unreserved bandwidth of 1Gbps, both paths (R1-R2-R4-R6 and R1-R3-R5-R6) are available. However, because of the least-fill feature, it's likely that the CSPF will choose the path that leaves the highest remaining bandwidth after the reservation. LSP-3 will take R1-R2-R4-R6 because it matches the conditions. Afterwards, LSP-4 is signaled requiring 800Mbps and it will take the only remaining path, R1-R3-R5-R6, as it has not yet been utilized. Thus, LSP-3 takes R1-R2-R4-R6 and LSP-4 takes R1-R3-R5-R6.
Pls post the topology. Thank you!